Thermo King V250 User Manual

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V250

TK 40839-1-MM (Rev. 2, 1/99)

1994 Thermo King Corp., Minneapolis, MN, U.S.A.

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The maintenance information in this manual covers unit models:

V250 10 (914500) Condenser 10 Plus (085067) V250 20 Generic (085007) Condenser 10 Plus UK (085068) V250 LOTEMP (715394) Kit - low temperature (715394) Condenser 10 (085001) E1000 Evaporator (085031) Evaporator - Thin Line (085003) E1000E Evaporator (085034) V250 115/1/60 Standby (085009) V250/E1000E Evaporator (085041) Evaporator (085005) V250 Converte (085066)

For further information, refer to…

V250 Parts Manual TK 40834 Diagnosing Thermo King Refrigeration Systems TK 5984 Tool Catalog TK 5955 V250 Operating Manual TK 40836 Installation Manual TK 41156

The information in this m anual is provided to as sist owners, operat ors and service peo ple in the proper upk eep and maintenance of Thermo King units. For detailed descriptions of Thermo King engines, compressors, or refrigeration systems , see the app ropria te Thermo King Over haul Man ual or Ref rigerat ion Syste ms Main tenanc e Manual.

This manual is published for informational purposes only and the information so provided should not be considered as all-inclusive or covering all c ont ing enc ie s. If fu rt her i nformation is required, T h er mo Ki ng C or por ation should be consulted.

Sale of product shown in this manual is subject to Thermo King’s terms and conditions including, but not limited to, the Thermo King Limited Express Warranty. Such terms and conditions are available upon request.

Thermo King’s warranty will not appl y to any equipm ent which has been “so r epaired or alter ed outside the manufacturer’s plants as, in the manufacturer’s judgment, to effect its stability.”

No warranties, express or implied, including warranties of fitness for a particular purpose or merchantability, or warr anties ar ising from c ourse o f dea ling or usage of trade, a re made rega rding the information , recommendations, and descriptions contained herein. Manufacturer is not responsible and will not be held liable in contract or in tort (including negligence) for any special, indirect or consequential damages, including injury or damage caused to vehicles, contents or persons, by reason of the installation of any Thermo King product or its mechanical failure.

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Recover Refrigerant

At Thermo King, we recognize the need to pr eserve the environment and limit the potential harm to the ozone layer that can result from allowing refrigerant to escape into the atmosphere.

We strictly adhere to a policy that promotes the recovery and limits the loss of refrigerant into the atmosphere.

In addition, service personnel must be a ware of Federal regulations concerning the use of refrigerants and the certification of technicians. For additional informatio n on regulations and technician certification programs, contact your local THERMO KING dealer.

R-404A R-134a

WARNING: Use ONLY Polyol Ester based refrigeration compressor oil (TK P/N 203-413) in R-404A and R-134a units.

DO NOT use Polyol Ester based oil in standard Thermo King units.

DO NOT mix Polyol Ester and standard synthetic compressor oils.

Keep Polyol Ester compressor oil in tightly sealed containers. If Polyol Ester oil becomes contaminated with moisture or standard oils, dispose of properly—DO NOT USE!

WARNING: When servicing Thermo King R-404A and R-134a units, use only those service

tools certified for and dedicated to R-404A or R-134a refrigerant and Polyol Ester compressor oils. Residual non-HFC refrigerants or oils will contaminate R-404A and R-134a systems.

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Table of Contents

Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . i

Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1

Maintenance Inspection Schedule. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Unit Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Liquid Injection System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Oil Separator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Unit Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Unit Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Protection Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Optional Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Serial Number Locations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Operating Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

Unit Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Unit Protection Devices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Unit Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

Bi-monthly Pre-Trip Checks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

Starting the Unit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

Adjusting the Thermostat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

After Start Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Loading Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .26

Post Loading Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27

Bi-monthly Post Trip Checks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

Electrical Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

Unit Wiring. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

Cab Control Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Selecting the Temperature Scale . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

Selecting the Setpoint Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Setpoint Differential Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Testing the Cab Control Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Display Diagnosis Chart . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Thermostat Switch Sequence Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33

Defrost System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

Engine Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34

Electric Standby Operation (Model 20) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Defrost Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35

V250 Defrost System and P.C. Board Identification and Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

P.C. Board Identification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Troubleshooting the V250 Defrost System with P.C. Board P/N 41-776 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41

Troubleshooting the V250 Defrost System with P.C. Boards P/N 41-1619 and P/N 41-1812 . . . . . . . . . . . . . .44

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Table of Contents (continued)

Electrical Maintenance (continued)

P.C. Board P/N 41-776 Test Procedure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

P.C. Board P/N 41-1812 and P/N 41-1619 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

M10 (V250/V-090) Cab Control Box Test Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49

Condenser Fan Pressure Switch (CFPS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

AC Components (Model 20) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Contactors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Overload Relay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

Electric Standby Circuits (Model 20 Only) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

12 Volt System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Evaporator Heaters (Optional) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52

Refrigeration Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Refrigerant Charge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Charging the Refrigeration System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

Checking the Refrigerant Charge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55

Checking Compressor Oil Charge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

High Pressure Cutout Switch (HPCO) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56

Low Pressure Cutout Switch (LPCO). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57

Cleanup Procedure for Small Truck Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58

Refrigeration Service Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Compressor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Condenser Coil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Drier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62

Receiver Tank . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

High Pressure Cutout and Condenser Fan Pressure Switches. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Hot Gas Solenoid Valve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Liquid Injection Solenoid Valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63

Oil Separator . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Liquid Injection Metering Orifice. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64

Testing the Liquid Injection Solenoid Valve and Metering Orifice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Check Valve Repair (Model 20 Only). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65

Evaporator Coil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68

Expansion Valve Assembly . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

Low Pressure Cutout Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Suction Pressure Regulator Valve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Replacing Refrigerant Hoses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

Page 6

Table of Contents—(continued)

V-250 R-404A Conversion Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73

Structural Maintenance. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

Unit Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

Evaporator Coil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75

Condenser Coil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75

Condenser Fan Location. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

Unit Mounting Bolts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75

Compressor and Clutch Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .77

Clutch Removal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .77

Clutch Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .79

Shaft Seal Cover and Shaft Seal: Removal and Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81

Special Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

System Compressor and Oil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86

Checking the Oil Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87

Electrical Connection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87

Clutch Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88

Belt Tensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88

Engine/Compressor Belt and Pulleys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88

Electric Motor/Compressor Belt. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89

Over-the-Road Mechanical Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

Road Compressors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92

Electric Standby Mechanical Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .93

Condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93

Possible Cause . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .93

Remedy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .93

Electric Standby Service Checks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96

V250 Installation Checklist . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .103

Wiring Diagrams and Schematic Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105

Page 7

Safety Precautions

GENERAL PRACTICES

1. ALWAYS WEAR GOGGLES OR SAFETY GLASSES. Refrigerant liquid, refrigeration oil, and battery acid can permanently damage the eyes (see First Aid under Refrigeration Oil).

2. Never operate the unit with the compress or discharge valve closed.

3. Keep your hands, clothing and tools clear of the fans and belts when the unit is running. This sh ould also be considered when opening and closing the compressor service valves.

4. Make sure gauge manifold hoses are in good condition. Never let them come in contact with a belt, fan motor pulley, or any hot surface.

5. Never apply heat to a sealed refrigeration system or container.

6. Fluorocarbon refrigerants, in the presence of an open flame or electrical short, produce toxic gases that are severe respiratory irritants capable of causing death.

REFRIGERANT

Although fluorocarbon refrigerants are classified as safe refrigerants, certain precautions must be observed when handling them or servicing a unit in which they are used. When exposed to the atmosphere from the liquid state, fluorocarbon refrigerants evaporator rapidly, freezing anything they contact.

First Aid

In the event of frost bite, the objectives of First Aid are to protect the frozen area from further injury, to warm the affected area rapidly and to maintain respiration.

• EYES: For contact with liquid, immediately flush eyes with large amounts of water and get prompt medical attention.

• SKIN: Flush area with large amounts of lukewarm water. Do not apply heat. Remove contaminated clothing and shoes. Wrap burns with dry, sterile, bulky dressing to protect from infection/injury. Get medical attention. Wash contaminated clothing before reuse.

7. Make sure all mounting bo lts are tight an d are of correct length for their particular application.

8. Use extreme caution when drilling holes in the unit. The holes may weaken structural components, and holes drilled into electrical wiring can cause fire or explosion.

9. Use caution when working around exposed coil fins. The fins can cause painful lacerations.

10. Use caution when working with a refrigerant or refrigeration system in any closed or confined area with a limited air supply (for example, a truck box or garage). Refrigerant tends to displace air and can cause oxygen depletion resulting in suffocation and possible death.

11. EPA Section 608 Certification is needed to work on refrigeration systems.

• INHALATION: Move victim to fresh air an d use CPR if necessary. Stay with victim until arrival of emergency medical personnel.

REFRIGERATION OIL

Avoid refrigeration oil contact with the eyes. Avoid prolonged or repeated contact of refrigeration oil with skin or clothing. Wash thoroughly after handling refrigeration oil to prevent irritation.

First Aid

In case of eye contact, immediately flush with plenty of water for at least 15 minutes. Wash skin with soap and water. CALL A PHYSICIAN.

Page 8

Safety Precautions (Rev 1/99)

ELECTRICAL HAZARDS

High Voltage

When servicing or repairing a refrigeration unit, the possibility of serious or even fatal injury from electrical shock exists. Extreme care must be used when working with an operating refrigeration unit. Lethal voltage potentials can exist on connections in the high voltage tray of the control box.

Precautions

1. When working on high v oltage circui ts on th e refrig eration unit, do not make any rapid moves. If a tool drops, do not grab for it. People do not contact high voltage wires on purpose. It occurs from an unplanned movement.

2. Use tools with insulated handles that are in good condition. Never hold metal tools in your hand if exposed, energized conductors are within reach.

3. Treat all wires and connections as high voltage until a meter and wiring diagram show otherwise.

4. Never work alone on high voltage circuits on the refrigeration unit, another person should always be standing by in the event of an accident to shut off the refrigeration unit and to aid a victim.

5. Have electrically insulated gloves, cable cutters and safety glasses available in the immediate vicinity in the event of an accident.

First Aid

IMMEDIATE action must be initiated after a person has received an electrical shock. Obtain immediate medical assistance if available.

The source of shock must be immediately removed by either shutting down the power or removing the victim from the source. If it is not possible to shut off the power, the wire should be cut with either an insulated instrument (e.g., a wooden handled axe or cable cutters with heavy insulated handles) or by a rescuer wearing electrically insulated gloves and saf et y gl ass e s. Wh ic hev er me th od i s us ed do no t look at the wire while it is being cut. The ensuing flash can cause burns and blindness.

If the victim has to be removed from a live circuit, pull the

victim off with a non-conductive material. Use the victim’s coat, a rope, wood, or loop your belt around the victim’s leg or arm and pull the victim off. DO NOT TOUCH the victim. You can receive a shock from current flowing through the victim’s body. After separating the victim from power source, check immediately for the presence of a pulse and respiration. If a pulse is not present, start CPR (Car dio Pulmonary Resuscitation) and call for emergency medical assistance. If a pulse is present, respiration may be restored by using mouth-to-mouth resuscitation, but call for emergency medical assistance.

Low Voltage

Control circuits used in the refrigeration unit are lo w voltage (12 volts dc). This voltage potential is not considered dangerous, but the large amount of current available (over 30 amperes) can cause severe burns if shorted or ground.

Do not wear jewelry, watch or rings. These items can short out electrical circuits and cause severe burns to the wearer.

Page 9

Specifications

General

Compressor Belt driven, multi cylind er, wobble plate type driven

by the truck engine (Model 10) and by the truck engine or electric motor. (Model 20)

Engine Compressor Oil Charge 6 oz (177 ml) in compressor

Total system: 12 oz (355 ml)

Electric Standby Compressor Oil Charge 6 oz 177 ml) in each compressor

Total system: 24 oz (710 ml) Compressor Oil Type Polyol Ester P/N 203-413 Defrost Method: Truck Engine Operation Model 10 Hot gas

Model 20 Hot gas Electric Standby Model 20 Hot gas Defrost Timer: Initiation Interval Adjustable, 1 hour to 10 hours

Termination interval 45 minutes

R-134A REFRIGERATION SYSTEM

Refrigerant Charge and Type 5 lb (2.3 kg) R-134a Defrost Termination Switch: Opens 52 F (11.1 C)

Closes 42 F (5.6 C)

Liquid Line Injection Switch: Opens 200 ± 5 F (93 ± 3 C)

Closes 230 ± 5 F (110 ± 3 C)

High Pressure Cutout Switch: Opens 350 + 25/-0 psi (2413 + 172/-0 kPa)

Closes 200 ± 20 psi (1379 ± 138 kPa)

Low Pressure Cutout: Opens 5 to 11 in. Hg vacuum (-17 to -34 kPa)

Closes 4 to 7 psi (28 to 48 kPa)

Condenser Fan Pressure Switch: Opens 130 ± 10 psi (896 ± 69 kPa)

Closes 180 ± 10 psi (1241 ± 69 kPa)

Page 10

Specifications (Rev 1/99)

R-404A REFRIGERATION SYSTEM

Refrigerant Charge and Type 5 lb (2.3 kg) R-404A Defrost Termination Switch: Opens 52 F (11.1 C)

Closes 42 F (5.6 C)

Liquid Line Injection Switch: Opens 200 ± 5 F (93 ± 3 C)

Closes 230 ± 5 F (110 ± 3 C)

High Pressure Cutout Switch: Opens 470 ± 7 psi (3241 ± 48 kPa)

Closes 375 ± 38 psi (2585 ± 262 kPa)

Low Pressure Cutout: Opens 5 to 11 in. Hg vacuum (-17 to -34 kPa)

Closes 4 to 7 psi (28 to 48 kPa)

Condenser Fan Pressure Switch: Opens 130 ± 10 psi (896 ± 69 kPa)

Closes 180 ± 10 psi (1241 ± 69 kPa)

ELECTRICAL SYSTEM

Fuses

F1 Condenser Fan Fuse 15 amps F2 Evaporator Fan Fuse 15 amps F3 Power Fuse 10 amps F4 Control Circuit Fuse 3 amps Battery Circuit Breaker 40 amps Transformer Fuse 4 amps (10 amps in 115/1/60 units) F5 Defrost Circuit Fuse 1 amp F7 Transformer Fuse 10 amps

Condenser and Evaporator Fan Motors

Voltage Horsepower

12 Vdc 0.17 0.12 1750-2000 6-9 amps

Hot Gas Solenoid and Liquid Injection Solenoid Coils

Voltage Current Resistance

Power Rating

in Kilowatts

rpm Full Load Current

12 Vdc 0.6-0.8 amps 15-19 ohms

Page 11

Electrical Standby Compressor Motors

Specifications (Rev 1/99)

Voltage Phase Frequency Horsepower Kilowatts

115 Vac 1 60 Hz 1.5 1.1 1750 15.0 16.0 230 Vac 1 60 Hz 2.0 1.5 1755 8.6 9.5 220 Vac 1 50 Hz 1.7 1.3 1460 10.0 11.0 230 Vac* 3 60 Hz 2.0 1.5 1695 6.8 3.5** 220 Vac* 3 50 Hz 1.6 1.2 1430 6.0 3.5** 400 Vac* 3 50 Hz 1.6 1.2 1405 3.2 3.5

* Motor can be wired for all three voltages.

**Overload relay monitors 1/2 motor windings on 220 and 230.

Optional Electri c Heaters

Voltage Power Rating Watts Current Resistance

230 Vac 1500 6.5 amps 35.3 ohms 400 Vac 1134 2.8 amps 141.1 ohms

BELT TENSION (Using Tool P/N 204-427)

Engine/Compressor 35 Electric Motor/Compressor 57

Field Reset

Full Load

rpm

Full Load

Current

(amps)

Overload

Relay Setting

(amps)

Page 12

Page 13

Maintenance Inspection Schedule

First Week Inspection and Maintenance

AFTER FIRST WEEK OF OPERATION:

• Check the belt tension

• Tighten the unit mounting bolts

• Check the refrigerant level

Bi-monthly Annually Inspect/Service These Items

ELECTRICAL

••

•

••

•

••

Check defrost initiation and termination. Check thermostat cycle sequence. Check operation of protection shutdown circuits. Check thermostat and thermometer calibration in 32 F (0 C) ice-water bath. Inspect wire harness for damaged wires or connections. Inspect/replace DC fan motor brushes.

REFRIGERATION

Check refrigerant level. Replace dehydrator.

STRUCTURAL

Visually inspect unit and refrigerant hoses for fluid leaks. Visually inspect unit for damaged, loose or broken parts. Clean defrost drains. Inspect belts for condition and proper tension (belt tension tool P/N 204-427). Clean entire unit including evaporator coil and condenser coil. Check all unit mounting bolts, brackets, lines, hoses, etc.

Page 14

Page 15

Unit Description

The Thermo King V250 is a truck refrigeration system that is designed for low and medium temperature applications on medium-sized trucks. There are two basic models:

• Model 10: C o ol a nd de fr os t o n en gin e -dr iv e n c o mp re ssor operation.

• Model 20: Cool and defrost on both truck enginedriven and electric standby compressor operation.

The system consist of three separate assemblies: the condenser, the evaporator, and the compressor.

The condenser has a unique design that allows it to be mounted horizontally or vertically, on the roof or on the front of the truck box.

The evaporator is mounted inside the truck box. Funnel and thin-line evaporators are available. The funnel evaporator mounts on the ceiling or the front wall. The thin-line evaporator mounts on the front wall.

The electric standby compressor is connected in parallel with the engine-driven compressor. The engine compressor is driven by a belt from the engine. Th e standb y compres sor is driven by a belt from the electric motor. Both compressors use the same refrigeration system circuit. Check valves isolate one compressor from the other during operation. Compressor operation is controlled by the thermostat, which energizes the compressor clutch during engine operation or starts the electric motor and energizes the compressor clutch on electric standby operation. The refrigeration system is protected by a high pressure cutout switch and a low pressure cutout switch.

The control circuits operate on 12 volts dc supplied by the truck battery for over-the-road operation. On standby operation, the power is rectified from an ac transformer.

The cab control box is mounted in the truck cab. It contai ns the On-Off key, Manual Defrost key, thermometer, thermostat, and indicator lights.

Liquid Injection System

Condenser and Evaporator Configurations

The compressor is mounted on and driven by the truck engine. Refrigeration hoses or lines are used to connect the condenser, the evaporator and the compressor. Model 20 units have another compressor and an electric motor mounted in the condenser section for electric standby operation.

If the discharge gas leaving the engine driven compressor reaches a temperature of 230 ± 5 F (110 ± 3 C), the liquid injection switch closes, providing voltage to the liquid injection solenoid. The solenoid opens a valve, allowing liquid refrigerant to flow from the liquid line near the receiver outlet valve to the metering orifice attached to the suction fitting at the compressor. As the refrigerant passes through the metering orifice it expands and evaporates, cooling the suction gas entering the compressor. This cooling effect is transferred to the dischar ge gas lea ving th e compresso r from the adjacent cavity in the compressor head. When the discharge gas is cooled to 2 00 ± 5 F (9 3 ± 3 C), the liquid injection switch opens, the liquid injection solenoid v alve closes and refrigerant no longer flows through the liquid injection system.

Page 16

Unit Description (Rev 1/99)

Oil Separator

An oil separator is a standard feature. It separates compressor oil from refrigerant vapor and returns the oil to the compressor through the oil fill hole by using a special adapter. The oil separator helps provide positive oil return at high compressor speeds and low operating temperatures. This feature enhances compressor lubrication and extends compressor life. Units built after November 1996 will be located in the condenser section. Refer to photo on page 12 and drawing on page 61.

UNIT OPERATION

These units shift between cool, null, and heat (optional) to maintain the box temperature at the thermostat setpoint. The operating modes are: cool, null, heat (optional), and defrost.

Engine Operation

The thermostat controls the operation of the unit by energizing and de-energizing the power relay and the heat relay. The thermostat places the unit in cool by energizing the power relay. The thermostat places the unit in null by deenergizing all the relays. The thermostat places the unit in heat by energizing the heat relay .

When the power relay is energized, power flows to energize the fan relay and the compressor clutch through normally closed contacts in ER2.

When the heat relay is energized, it closes contacts that energize the fan relay, the water pump, and the water valve.

When the fan relay is energized, it closes contacts that energize the condenser and evaporator fans. The condenser fan is also controlled by the condenser fan pressure switch. This normally open switch monitors the compressor discharge pressure. When the discharg e pressure rises to 180 ± 10 psi (1241 ± 69 kPa), the switch closes and energizes the condenser fan. When the discharge pressure drops to 130 ± 10 psi (896 ± 69 kPa), th e swit ch opens and de-ener gi zes the condenser fan.

Electric Standby Operation

During electric standby operation, the thermostat controls the operation of the unit by energizing and de-energizing the power relay, the electric relays, and the heat contactor. The thermostat places the unit in cool by energizing the power relay and the electric relays.

The thermostat places the unit in null by de-energizing all the relays and contactors. The thermostat places the unit in heat by energizing the heat contactor.

When the power relay and the electric relays are energized, they close contacts that energize the fan relay, the motor contactor, and the electric standby compressor clutch.

When the heat contactor is energized, it energizes the electric evaporator heaters and the fan relay.

Cool

The thermostat shifts the unit to cool at temperatures more than 5.4 F (3 C) above the thermostat setpoint. The thermostat keeps the unit running in cool until the temperature falls to the thermostat setpoint.

During engine operation the engine compressor and the evaporator fans operate while the unit is in co ol. During electric operation, the electric motor, the electric standby compressor, and the evaporator fans operate while the unit is in cool.

Null

The thermostat shifts the unit from cool to null at the thermostat setpoint. The thermostat shifts the unit from null to heat at 3 F (1.7 C) below the thermostat setpoint. The thermostat shifts the unit from heat to null at 2.4 F (1.3 C) above the thermostat setpoint. The thermostat shifts the unit from null to cool at 5.4 F (3 C) above the thermostat setpoint.

Page 17

Heat (Optional)

The thermostat shifts the unit to heat at temperatures more than 3 F (1.7 C) below the thermostat setpoint. Th e therm ostat keeps the unit running in heat un til the temp erature ris es to 2.4 F (1.3 C) above the thermostat setpoint. During engine operation, the water pump and the evaporator fans operate while the unit is in heat.

During electric operation, the evaporator heaters and the evaporator fans operate while the unit is in heat.

Defrost

The defrost cycle can be initiated any time the evaporator coil temperature is below 42 F (5.6 C). Defrost is initiated automatically by the defrost timer, or manually by pressing the Manual Defrost switch.

Unit Description (Rev 1/99)

AGA329

Initiating defrost energizes the defrost relay. This energizes the hot gas solenoid to route hot gas to the evaporator, and de-energizes the fan relay to stop the evaporator and condenser fans.

The unit runs in defrost until the evaporator coil temperature rises to 52 F (11.1 C), causing the defrost termination switch to open. This de-energizes the defrost relay and terminates defrost. If the defrost termination switch does not open in less than 45 minutes, the defrost timer will terminate the defrost cycle 45 minutes after is was started.

0Setpoint 1 Temperature Drop 2 Temperature Rise 3Cool 4Null 5 Heat (Optional)

(1) Shifts from Null to Cool if not previously in Heat (2) Shifts from Null to Heat if not previously in Cool

Thermostat Algorithm

UNIT FEATURES

• Digital Thermometer

• Electronic Thermostat

• Defrost Timer

• Hot Gas Defrost

• Defrost Termination Switch

• Liquid Injection System

Page 18

Unit Description (Rev 1/99)

• Manual Defrost Key

• Suction Pressure Regulator

• Oil Separator

• Six Cylinder Compressor

• R-134a

Unit Features (continued)

• Standby Electric Motor and Six Cylinder Standby Compressor (Model 20 only)

• Refrigerant Flow Controlled Between Compressors by Discharge Check Valve (Model 20 only)

PROTECTION FEATURES

• Control Circuit Fuses

• Refrigerant High Pressure Cutout

• Refrigerant Low Pressure Cuto ut

• Heat, Truck Engine and Electric Standby Heater St rips

(Model 20)

• Paint, Special Color

• 24 V dc Converter

• R-404A Dealer Installed

SERIAL NUMBER LOCATIONS

Condenser: Roadside. Evaporator: Roadside panel. Compressor: Nameplate on compressor body. Standby Motor: Nameplate on motor.

• Refrigerant High Pressure Relief Valve

• Power Cord Warning Light (in Cab Control Box)

• Overload Relay Protection for Electric Standby Motor

(Model 20 o nl y)

• Transformer Fuses (Model 20 only)

OPTIONAL FEATURES

• Electric Motors (Model 20 only) 115 Volt/1 Phase/60 Hz 220 Volt/1 Phase/50 Hz 230 Volt/1 Phase/60 Hz 220 Volt/3 Phase/50 Hz 230 Volt/3 Phase/60 Hz 400 Volt/3 Phase/50 Hz

• Heat, Truck Engine (Model 10)

Page 19

Unit Description (Rev 1/99)

AGA339

Vertical Mounted Condenser (Early Model)

AGA673

Vertical Mounted Condenser (Later Model)

Page 20

Unit Description (Rev 1/99)

12 4356

9101113

1. High Voltage Box 8. Oil Separator

2. Compressor 9. Liquid Injection Solenoi d

3. Hot Gas Solenoid (Behind Fan Blade ) 10. Drier

4. Hourmeters Location (Optional) 11. Condenser Coil

5. Low Voltage Box 12. Check Valve Assembly

6. Condenser Fan 13. Motor (Model 20 only)

7. Receiver Tank 14. 24 Volt Converter

Condenser Components—Front/Top View (Starting 1997)

AEA825

Page 21

Unit Description (Rev 1/99)

1. Expansion Valve 3. Fan Motor

2. Thermostat Sensor 4. Suction Pressure Regulator

Funnel Evaporator

Page 22

Unit Description (Rev 1/99)

1. Thermostat Sensor 4. Expansion Valve

2. Heat Exchanger 5. Evaporator Coil

3. Suction Pressure Regulator

Thin-Line Evaporator

Page 23

Unit Description (Rev 1/99)

AEA667

1. Relays 2. PC Board

Low Voltage Box—Pre-1996

Page 24

Unit Description (Rev 1/99)

AEA660

1. Transformer 6. Transformer Fuse

2. Motor Start Capacitors 7. Overload Relay

3. Motor Start Relay 8. Motor Contactor

4. DC Power Filter Capacitor 9. Heat Contactor (Optional)

5. Motor Run Capacitor

High Voltage Box—Pre-1997

Page 25

Unit Description (Rev 1/99)

AEA826

2345

1. Transformer 6. Transformer Fuse

2. Motor Start Capacitors 7. Overload Relay

3. DC Power Filter Capacitor 8. Motor Contactor

4. Motor Run Capacitor 9. Heat Contactor (Optional)

5. Motor Start Relay

High Voltage Box—Starting 1997

Page 26

Unit Description (Rev 1/99)

1. D.C. Power Filter Capacitor 5. Transformer

2. Motor Starting Capacitor 6. Motor Contactor

3. Motor Start Relay 7. Fuse and Fuseholder

4. Motor Run Capacitor 8. Motor Protector

High Voltage Box - Typical for Single Phase P97

AGA340

Page 27

Unit Description (Rev 1/99)

AGA345

1. D.C. Power Filter Capacitor 4. Motor Contactor

2. Transformer 5. Fuse and Fuse Holder

3. Overload Relay

High Voltage Box - Typical fo r 3 Phase P97

Page 28

Unit Description (Rev 1/99)

123 4 5 6 7

91011121314

1. Power Cord Indicator 8. Thermostat Dial

2. Running Indicator 9. Setpoint Key

3. Defrost Indicator 10. AC Overload Indicator

4. Heat Indicator 11. Digital Display

5. Cool Indicator 12. Manual Defrost Key

6. Celsius Indicator 13. On-Off Key

7. Fahrenheit Indicator 14. On Indicator

Cab Control Box—M10 Pre-1997

AEA661

Page 29

Unit Description (Rev 1/99)

NOTE: The M13 and M10 cab boxes a re identified by th e position of the d efrost indicator li ght. On the M13 cab box the defrost indicator light is po sitioned on the def rost key. On the M10 cab box t he defrost indica tor light is pos itioned left of the digital display. Refer to the following illustrations. Refer to Service Bulletin 177.

AEA835

1. Defrost Indicator Light

M13 Cab Box—TK No. 45-1780

1. Defrost Indicator Light

M10 Cab Box—TK No. 45-1705

AEA836

Page 30

Page 31

Operating Instructions

UNIT CONTROLS

Cab Control Box

1. ON-OFF KEY. Press this key to turn the unit ON and OFF.

2. ON INDICATOR. When this light is on, it indicates that the unit is turned ON. When this light is off, it indicates that the unit is turned OFF.

3. POWER CORD INDICAT OR. When this light is on, it indicates that the unit is connected to an electric standby power source.

4. RUNNING INDICATOR. When this light is on, it indicates that the unit is running.

5. MANUAL DEFROST KEY. Press this key to start a defrost cycle. The unit will not defrost unless the defrost termination switch is closed (evaporator coil temperature below 42 F [5.6 C]).

6. DEFROST INDICATOR. When this light is on, it indicates that the unit is in defrost.

7. DIGITAL DISPLAY. This display is active only when the unit is turned on. The thermometer reading (return air sensor temperature) normally appears on the display. Pressing the setpoint key causes the thermostat setpoint to appear on the di splay for 10 t o 15 seconds.

12. AC OVERLOAD INDICATOR. When this light is on, it indicates that the overload relay has opened. This indicator must be reset by pressing the On-Off Key after allowing time for the overload relay to cool.

13. SETPOINT KEY. Press this key to make the thermostat setpoint appear on the digital display. The thermostat setpoint will remain on the display for 10 to 15 seconds after the key is released. This gives the operator time to adjust the thermostat setpoint.

14. THERMOSTAT DIAL. Turn this dial to adjust the thermostat setpoint.

NOTE: The Thermostat Dial will change the thermostat setpoint without pressing the Setpoint Key.

Low Voltage Box

1. DEFROST TIMER. The defrost timer is built-in to the PC board. It can automatically initiat e or terminate a defrost cycle if necessary. The initiation interval is adjustable from 1 hour to 10 hours. The termination interval is set at 45 minutes. Refer to the Electrical Maintenance section for more information about the defrost timer.

2. CONTROL RELAYS. Six control relays are located on the PC board. These relays are used to control the operation of the unit.

8. HEAT INDICATOR. When this light is on, it indicates that the unit is running in heat.

9. COOL INDICATOR. When this light is on, it indicates that the unit is running in cool.

10. CELSIUS INDICATOR. When t his light is on, it indicates that the temperature is being displayed in degrees Celsius.

11. FAHRENHEIT INDICATOR. Wh en this light is o n, it indicates that the temperature is being displayed in degrees Fahrenheit.

3. ENGINE HOURMETER (Optional). This hourmeter records the amount of time the unit runs on engine operation.

4. ELECTRIC HOURMETER (Model 20) (Optional). This hourmeter records the amo unt o f time the un it runs on electric standby operation.

High Voltage Box (Model 20)

1. MOTOR CONTACTOR. The motor contactor is used to control the operation of the electric motor that drives the electric standby compressor .

Page 32

Operating Instructions (Rev 1/99)

2. HEATER CONTACTOR (Optional). The heater contactor is used to control the operation of the optional electric evaporator heaters.

Other Controls

1. DEFROST TERMINATION SWITCH. This temperature sensitive switch is located on the evaporator coil. It closes to enable defrost when the evaporator coil temperature falls below 42 F (5.6 C).

The switch opens to terminate, or disable, defrost when the evaporator coil temperature rises to 52 F (11.1 C).

2. CONDENSER FAN PRESSURE SWITCH. This pressure sensitive switch is located on the receiver tank. When the pressure in the receiver tank rises above 180 psi (1241 kPa), the switch closes to energized the condenser fan. When the pressure in the receiver tank falls below 130 psi (896 kPa), the switch opens to de-energize the condenser fan.

3. LIQUID INJECTION SWITCH. This temperature sensitive switch is located on the discharge fitting of the truck engine compressor. When the discharge temperature rises above 230 F (110 C), the switch closes to open the liquid injection solenoid. When the disch arge temperature falls below 200 F (93 C), the switch opens to close the liquid injection solenoid.

4. SUCTION PRESSURE REGULATOR VALVE. This valve is located in the suction line in the evaporator. It limits the suction pressure at the comp ressor. The normal pressure setting for this valve is 18 to 20 psi (124 to 138 kPa).

UNIT PROTECTION DEVICES

1. PC BOARD FUSES. Five fuses are located on the PC board in the low voltage box.

F1 This 15 amp fuse protects the circuit to the con-

denser fan m otor.

F2 This 15 amp fuse protects the circuit to the evapo-

rator fan motor.

F3 This 10 amp fuse protects the circuit to the power

relay and the heat relay.

F4 This 3 amp fuse protects the circuit from the trans-

former output to the cab control box. F5 Defros t Circ uit Fuse. 1 Amp F6 A 40 amp fuse protects the battery circuit. F7 A 10 amp fuse protects transformer motor circuit

for 115V/1 Ph/60 Hz, 230V,1 Ph/60 Hz, and 230V/

1 Ph/50 Hz. A 4 amp fuse protects the transformer

motor circuit for 230V and 400V at 3 Ph, 50 units

and 230V, 3 Ph, 60 Hz units.

2. CIRCUIT BR EAKER. A 40 a mp circuit breaker or 40 amp fuse protects the circuit from the vehicle battery to the unit.

3. HIGH PRESSURE CUTOUT SWITCH. This pressure sensitive switch is located on the receiver tank. If the pressure in the receiver tank rises above 350 psi (2413 kPa) for R-134a systems or 470 psi (3241 kPa) for R404A systems, the switch opens the circuit to the power relay, which stops the unit.

NOTE: This operation is for units with printed circuit board manufactured prior to 3-25-96 (s ee “P.C. Bo ar d P/N 41-776 (First Version)” on page 38).

When the HPCO opens on models using printed ciruit board manufactured between 3-26-96 and 5-21-96, see “P.C. Board P/N 41-1619 (Second Version)” on page 39 or after 5-21-96 (see “P.C. Board P/N 411812 (Third Version)” on page 40) the HPCO will cycle the compressor clutch only.

4. LOW PRESSURE CUTOUT SW ITCH. This p ressure sensitive switch is located on the suction line in the evaporator. If the pressure in the suction line falls

Page 33

Operating Instructions (Rev 1/99)

below 5 to 11 in. Hg of vacuum (-17 to -37 kPa), the switch opens the circuit to the power relay, which stops the unit.

NOTE: This operation is for units with printed circuit

board manufactured p rior to 3-25-96 (see “P.C. Board P/N 41-776 (First Vers ion)” on page 38).

When the LPCO opens on models using printed cirucit board manufactured between 3-26-96 and 5-21 -96, see “P.C. Board P/N 41-1619 (Second Version)” on page 39 or after 5-21-96 (see “P.C. Board P/N 411812 (Third Version)” on page 40) the HPCO will cycle the compressor clutch only.

5. FUSE PLUG. The fuse plug is located on the receiver tank. It opens to relieve the pressure in the refrigeration system if the pressure becomes excessive. If the fuse plug has opened, it must be replaced. It cannot be reused.

6. OVERLOAD RELAY (Model 20). This auto reset relay protects the electric motor that drives the electric standby compressor. The overload relay opens the circuit to the cab control box, which de-energizes the motor contactor and the electric motor if the motor overloads for any reason (e.g., low line voltage or improper power supply) during electric standby operation. When the overload relay opens, it illuminates the AC overload indicator.

7. TRANSFORMER FUSE (Model 20). This fuse is located in the high voltage box. The 115 volt, single phase, 60 Hz unit has a 10 amp f use. Al l oth er uni ts use a 4 amp fuse.

inspection is not a substitute for regularly scheduled maintenance inspections, it is an important part of t he preventive maintenance program designed to head off operating problems before they happen.

1. LEAKS. Inspect for refrigerant leaks and worn refrigerant lines.

2. BELTS. Inspect for cracks, wear and proper tensions.

3. ELECTRICAL INSPECTION. The electrical connections should be securely fastened. Wires and terminals should be free of corrosion, cracks or moisture.

4. DEFROST DRAINS. Check the defrost drain hoses and fittings to make sure that they are open so condensate can run out during defrost. Check the bottom end of each drain hose to make sure that it is not plugged or crushed.

5. STRUCTURAL INSPECTION. Visually check for physical damage.

6. REFRIGERANT CHARGE. Check the receiver tank sight glass for the proper charge level.

Starting the Unit

Model 10 Units

1. Start the truck engine.

2. Press the On-Off key in the cab control box to turn the unit ON.

3. Adjust the thermostat to the proper setting.

Model 20 Units

UNIT OPERATION

Bi-monthly Pre-Trip Checks

The following bi-monthly pre-trip inspection should be completed before loading the truck. While the bi-monthly

Engine Operation

1. Start the truck engine.

2. Press the On-Off Key in the cab control box to turn the unit ON.

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Operating Instructions (Rev 1/99)

3. Adjust the thermostat to the proper setting.

NOTE: The power cord indicator will come on if the unit is connected to an electric standby power supply.

Electric Standby Operation

1. Connect the electric standby power supply to the unit’s power receptacle. Make sure that the power supply has the proper voltage and phasing.

2. Press the On-Off Key in the cab control box to turn the unit ON.

3. Adjust the thermostat to the proper setting.

NOTE: The power cord indicator will come on while the unit is connected to an electric standby power supply.

Adjusting the Thermostat

The thermometer reading (return air sensor temperature) normally appears on the digital display while the unit is turned ON. Pressing the Setpoint Key causes the thermostat setpoint to appear on the di splay for 10 to 15 seconds.

1. Press the Setpoint Key to display the setpoint. The setpoint will appear on the display for 10 to 15 seconds.

2. PRECOOLING. With the thermostat set at the correct temperature, allow the unit to run for one-half to one hour (longer if possible) before loading the truck. Precooling will remove residual body heat and moisture from the box interior and provide a good test of the refrigeration system.

3. DEFROST. When the unit has finished pre-cooling the truck interior (the evaporator temperature has dropped below 42 F (5.6 C), initiate a defrost cycle with the Manual Defrost switch. The defrost cycle should end automatically.

Loading Procedure

1. Make sure that the unit is OFF before opening the doors to minimize frost accumulation on the evaporator coil and heat gain in the truck. (The unit may be running when the truck is being loaded from a warehouse with door seals.)

2. Spot check and record the load temperature while loading. Especially note any off-temperature product.

3. Load the product so there is adequate space for air circulation completely around the load. DO NOT block the evaporator inlet or outlet.

2. Turn the Thermostat Dial to adjust the setpoint to the proper setting while the setpoint is being displayed.

3. After the thermometer reading appears on the display, press the Setpoint Key to check the setpoint.

NOTE: The Thermostat Dial will change the setpoint without pressing the Setpoint Key. Do not turn the Thermostat Dial without checking the setpoint.

After Start Inspection

1. THERMOSTAT. Adjust the thermostat setting above and below the box temperature to check the thermostat operation (see Operating Modes).

4. Products should be precooled before loading. Thermo King units are designed to maintain loads at the temperature at which they are loaded. Transport refrigeration units are not designed to pull hot loads down t o te mp erature.

Post Loading Procedure

1. Make sure that all the doors are closed and locked.

2. Adjust the thermostat to the desired temperature setpoint.

3. Start the unit.

Page 35

4. One-half hour after loading, def rost the uni t by momentarily pressing the Manual Defrost switch. If the coil temperature has dropped below 42 F (5.6 C), the unit will defrost. The defrost cycle should stop automatically.

Bi-monthly Post Trip Checks

1. Wash the unit.

2. Check for leaks.

3. Check for loose or missing hardware.

4. Check for physical damage to the unit.

Operating Instructions (Rev 1/99)

Page 36

Page 37

Electrical Maintenance

UNIT WIRING

Periodically inspect the unit wiring and the wire harnesses for loose, chafed or broken wires to protect against unit malfunctions due to open or short circuits.

CAB CONTROL BOX

Selecting the Temperature Scale

The temperature readings can be displayed in eith er the Celsius scale or the Fahrenheit scale. Dip switch 3, located inside the cab control box, is used to select which scale is displayed. In dicator lights next to the digital display show which scale has been selected. Place dip switch 3 in the ON position to display temperatures in degrees Celsius.

Place dip switch 3 in the OFF position to display temperatures in degrees Fahrenheit. To change the temperature scale selection:

1. Remove the cover from the back of the cab control box.

2. Place dip switch 3 in the proper position. ON for Celsius OFF for Fahr e nheit

3. Replace the cover.

Selecting the Setpoint Range

The setpoint range can be set at either -26 to 86 F (-32 to 30 C) or -8 to 86 F (-22 to 30 C). Dip switches 1 and 2, located inside the cab control box, are used to select the setpoint range. Place dip switches 1 and 2 in the ON position for a setpoint range of -26 to 86 F (-32 to 30 C). Place dip switches 1 and 2 in the OFF positio n for a setpo int range of

-8 to 86 F (-22 to 30 C). To change the setpoint range selec-

tion:

1. Remove the cover from the back of the cab contro l box.

2. Place dip switches 1 and 2 in the proper position. ON for a setpoint range of -26 to 86 F (-32 to 30 C). OFF for a setpoint range of -8 to 86 F (-22 to 30 C).

3. Replace the cover.

1. Dip Switches

Back of Cab Control Box with Cover Removed

Page 38

Electrical Maintenance (Rev 1/99)

NOTE: Do not run a R-1 34a un i t t o -2 6 F (-3 2 C). R-404A units may be operated at -24 F (-32 C).

Setpoint Differential Adjustment

Adjust the thermostat setpoint differential to 4 F (2 C).

1. Remove the cab control box from its bracket.

2. Remove the cover from th e back o f the cab contro l bo x.

3. Turn the adjusting potentiometer to the 12 o’clock position.

4. Replace the cover and place the cab contro l box back in its bracket.

1. 1 Amp Fuse

2. 12/24 Volt Jumper

3. Main Harness Plug

4. Dip Switches

5. Sensor Plug

6. Setpoint Differential Potentiometer Set to 12 o’cl oc k pos it ion

Adjust Setpoint Differential

Page 39

Electrical Maintenance (Rev 1/99)

Testing the Cab Control Box

The cab control box contains the thermometer and the thermostat. The thermometer and the thermostat share the same digital display and use the same sensor. The thermometer displays the sensor temperature. The thermostat compares the sensor temperature with the setpoint to determine the unit’s operating mode. The sensor is normally located in the evaporator return airflow.

Thermometer

The range for the thermometer is -40 to 99 F (-40 to 38 C). Normally the thermometer reading appears on the digital display. Pressing the Setpoint key causes the thermostat setpoint to appear on the digital display for 10 to 15 seconds.

Thermostat

The setpoint range for the thermostat is -26 to 86 F (-32 to 30 C) or -8 to 86 F (-22 to 30 C). The thermostat setpoint appears on the digital display when the Setpoint key is pressed. Turning the thermostat dial changes the setpoint. The thermostat controls the operation of the unit by controlling the power relay, the heat relay, and the electric relays.

Initial Digital Display Test

1. Turn the un it ON. Note what ap pears o n the digital dis play. This is the temperature display.

a. Normal Display (-40 to 199 F [-40 to 38 C]) b. Blank Display c. Erratic Display

2. Press the Setpoint key and note what appears on the digital display. This is the setpoint display.

a. Normal Display (-26 to 8 6 F [-32 to 30 C]) b. Blank Display c. Erratic Display d. No Change

3. Refer to the Display Diagnosis Chart to see what to check next.

Check Power—Engine Operation

1. Make sure that the condenser cover is on the unit.

2. Remove the cover from the back of the cab contro l box.

Temperature

Display

3. Start the truck engine and turn the unit ON.

Display Diagnosis Chart

Setpoint Display

Normal Display Blank Display Erratic Display No Change

Normal Display Blank Display Check Sensor Check Power Check Power Check Power

Erratic Display Check Sensor Check Power Check Power Check Power

No Problem Faulty Cab

Control Box

Faulty Cab

Control Box

Faulty Cab

Control Box

Page 40

Electrical Maintenance (Rev 1/99)

Steps 4 and 5 refer to Wiring Diagram 5D44456 and Schematic Diagram 5D44455.

4. Check the voltage between the 2R3 circuit (pin 3) and the CH circuit (pin 9) in the connector on the back of the cab control box. Battery voltage (12 volts).

5. If battery voltage is not present, check the wiring and connectors in the circuit to the vehicle accessory terminal 2R3 and SW2 on the PC board. Make sure that the vehicle accessory terminal has power.

Steps 6 and 7 refer to Wiring Diagram 5D46190 and Schematic Diagram 5D46179.

6. Check the voltage between the ACD circuit (pin 3) and the CH circuit (pin 9) in the connector on the back or the cab control box. Battery voltage (12 volts).

7. If the battery voltage is not present, check the wiring and connectors in the circuit to the vehicle accessory terminal, ACD. Make sure that the vehicle accessory has power.

Check Power—Electric Standby Operation

proper output voltages (X3-X4) and make sure that the electric standby power supply is turned ON.

Steps 6 and 7 refer to Wiring Diagram 5D46190 and Schematic Diagram 5D46179.

6. Check the voltage between 2R1 (pin 2) and the CH circuit (pin 9) in the connector on the back of the cab control box. Transformer output voltage (12 volts) should be present.

7. If voltage is not present, check the wiring, connectors and components to the transformer (L1, L3; 2R2, 2R2; and F7) fuse. Check the transformer for the proper output voltages (X3-X4) and make sure that the electric power standby is ON.

Check Sensor

A good sensor should have a resistance of 805 to 825 ohms at a temperature of 32 F (0 C). To check a sensor:

1. Disconnect the sensor wires form the back of the cab control box and connect the sensor wires to an accurate ohmmeter.

1. Make sure that the condenser cover is on the unit.

2. Remove the cover from the back of the cab contro l box.

3. Connect the unit to an appropriate electric standby power supply and turn the unit ON.

Steps 4 and 5 refer to Wiring Diagram 5D44456 and Schematic Diagram 5D44455

4. Check the voltage between the 2R2 circuit (pin 2) and the CH circuit (pin 9) in the connector on the back of the cab control box. Transformer output voltage (12 volts) should be present.

5. If voltage is not present, check the wiring, connectors, and components in the circuit to the transformer (L1, L3; 2R2, 2R 1; F5 fuse). Check the t ransforme r for the

2. Remove the sensor from the evaporator and place the sensor in an ice water bath at 32 F (0 C). Use a reliable thermometer to confirm the temperature of the ice water bath. Make sure that the sensor is in the ice water bath long enough (a few mi nute s) for th e temperatu re to saturate the sensor.

3. Check the resistance of the sensor. It should be 805 to 825 ohms. If not, check the sensor wires to make sure that they are not damaged. If the sensor wires are not damaged, the sensor is defective.

4. If the sensor is not defective, reconnect the sensor wires to the back of the cab control box and check the thermometer display. If th e thermometer display is not normal, attach a new sensor to the cab control box and recheck the thermometer display. If thermometer display is still not normal, the cab control box is defective.

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Electrical Maintenance (Rev 1/99)

Faulty Cab Control Box

Before replacing the cab control box make sure that another problem, such as a l oose wire connection or a bad ground, is not causing the cab control box to malfunction.

Thermometer Calibration Test

1. Place the sensor in an ice-water bath for a few minutes and allow the sensor temperature to stabilize.

2. Check the thermometer reading. It should be 32 ± 2 F (0 ± 1 C).

3. If the thermometer reading is out of calibration, replace the sensor and repeat the test.

4. If the thermometer reading is still out of calibration, the cab control box is defective.

Thermostat Switch Sequence Test

This test should be performed during scheduled preventive maintenance operations. Make sure that the thermometer is calibrated before performing this test.

NOTE: Press the Setpoint key to display the thermostat setpoint.

3. Continue to slowly turn the thermostat dial up to raise the thermostat setpoint about 2 F (1 C) every 5 seconds. When the thermostat setpoint is approximately 3.6 F (2 C) above the thermometer reading, the Heat Indicator and the Running Indicator should both come on, the heat relay should energize, and the unit should shift to heat.

4. Slowly turn the thermostat dial d own to lower the thermostat setpoint about 2 F (1 C) every 5 seconds. When the thermostat setpoint is equal to the thermometer reading, the Heat Indicator and the Running Indicator should both go off, the heat relay should de-energize, and the unit should shift to null.

5. Continue to slowly turn the thermostat dial down to lower the thermostat setpoint about 2 F (1 C) every 5 seconds. When the thermostat setpoint is ap proximately

3.6 F (2 C) below the thermometer reading, the Cool Indicator and the Running Indicator should both come on, the power relay should ener gize, an d the unit s hould shift to cool.

If the indicator lights do not come on and go off properly, and if the unit does not shift operating modes properly, the cab control box is probably defective.

Engine Operation Test

1. Start the unit on engine operation and set the thermostat at least 6.3 F (3.5 C) below the thermometer reading. The Cool Indicator and the Running Indicator should be on, the Heat In dica to r sho u ld be off, t he po we r rela y should be energized, the heat relay should be de-energized, and the unit should be running in cool.

2. Slowly turn the thermostat dial up to raise the thermostat setpoint about 2 F (1 C) every 5 seconds. When the thermostat setpoint is approximately equal to the thermometer reading, the Cool Indicator and the Running Indicator should both go of f, the pow er relay shou ld deenergize, and the unit should shift to null.

If the indicator lights come on and go off properly, but the unit does not shift operating modes properly, make sure that the power relay, the heat relay , the associated wiring and the wire connections are not defective before assuming that the cab control box is defective. Specifically:

1. The thermostat energizes the power relay by energizing pin 6 in the connector on the back of the cab control box.

2. The thermostat energizes the heat relay by grounding pin 10 in the connector on the back of the cab control box.

Therefore, the cab control box is no t def ective if it energizes pin 6 and grounds pin 10 properly.

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Electrical Maintenance (Rev 1/99)

Electric Standby Operation Test

1. Start the unit on standby operation and set the thermostat at least 6.3 F (3.5 C) below the thermometer reading. The Cool Indicator and the Running Indicator should both be on, the Heat Indicator should be off, the electric relays should be energized, the heat contactor should be de-energized, and the unit should be running in cool.

2. Slowly turn the thermostat dial up to raise the thermostat setpoint about 2 F (1 C) every 5 seconds. When the thermostat setpoint is approximately equal to the thermometer reading, the Cool Indicator and the Running Indicator should both go off, the electric relays should de-energize, and the unit should shift to null.

3. Continue to slowly turn the thermostat dial up to raise the thermostat setpoint about 2 F (1 C) every 5 seconds. When the thermostat setpoint is approximately

3.6 F (2 C) above the thermometer reading, the Heat Indicator and the Running Indicator should both come on, the heat contactor should energize, and the unit should shift to heat (optional).

4. Slowly turn the thermostat dial dow n to lower th e thermostat setpoint about 2 F (1 C) ev ery 5 seco nds. Wh en the thermostat setpoint is equal to the thermometer reading, the Heat Indicator and the Running Indicator should both go off, the heat contacto r should de-energize, and the unit should shift to null.

5. Continue to slowly turn the thermostat dial down to lower the thermostat setpoint about 2 F (1 C) every 5 seconds. When the thermostat setpoint is approximately

3.6 F (2 C) below the thermometer r eading, the Cool Indictor and the Running Indicator should both come on, the electric relays should energize, and the unit should shift to cool.

If the indicator lights do not come on and go off properly, and if the unit does not shift operating modes properly, the cab control box is probably defective.

If the indicator lights come on and go off properly, but the unit does not shift operating modes properly, make sure that the electric relays, the heat contactor, the associated wiring and the wire connections are not defective before assuming that the cab control box is defective. Specifically:

1. The thermostat energizes the electric relays by energizing pin 1 in the connector on the back of the cab control box.

2. The thermostat energizes the heat contactor by grounding pin 10 in the connector on the back of the cab control box.

Therefore, the cab control box is no t def ective if it energizes the pin 1 and grounds pin 10 properly.

DEFROST SYSTEM

Engine Operation

A defrost cycle can be initiated by pressing the manual defrost key or by the defrost ti mer when the defr ost term ination switch is closed. Starting a defrost cycle energizes the defrost relay which energizes the hot gas solenoid and deenergizes the fan relays. Energizing the hot gas solenoid diverts hot gas into the evaporator coil to melt the frost and ice. De-energizing the fan relay stops the evaporator and condenser fans.

The defrost termination switch de-energizes the defrost relay when the evaporator temperature rises above 52 F (11.1 C).

To check the defrost cycle, run the unit in cool to drop the evaporator coil to a temperature below 42 F (5.6 C). Press the manual defrost key. The unit should shift from the cool to defrost. If the unit continues to cool, double check the evaporator coil temperature, and refer to Testing the Defrost System.

Page 43

Electrical Maintenance (Rev 1/99)

NOTE: It takes more time to complete a defrost cycle in low ambient temperatures (below 35 F [2 C]) than it does in high ambient temperatures (above 70 F [21 C]). Therefore, consider the ambient temperature before deciding that a unit is not defrosting proper ly.

Electric Standby Operation (Model 20)

Defrost operates essentially the same on electric standby as it does on engine operation.

Defrost Components

Defrost Timer

The defrost timer is built-in to the PC b oard in the low voltage box. It initiates and, if necessary, terminates the defrost cycle.

The initiation interval for the defrost timer is adjustable. It can be set at intervals ranging from 1 hour to 10 hours. The initiation interval begins when the defrost termination switch closes. Every time the defrost termination switch opens, the timer resets to zero.

(5.6 C), completing the defrost circuit to ground (CH) and preparing the electrical system for the defrost cycle.

When the unit does shift into a defrost cycle, the evaporator fan stops, and heat from the hot refrigerant gas melts the frost from the evaporator coil. The switch opens and terminates the defrost cycle when the evaporator coil temperature rises to 52 F (11.1 C).

Installation

The proper polarity must be observed when installing the defrost termination switch. The wire from the switch is negative and must be attached to the chassis ground of the unit. This chassis ground wire cannot be attached to either of the switch moun ting scre ws or an im proper g round m ay result. The 12 wire from the unit attaches to the screw terminal that is mounted solidly on the switch. If the polarity is rever sed on the device, it will conduct continuously and act like a switch that is stuck closed.

At the initiation of the defrost cycle, a 45 minute ti mer is activated. If the defrost termination switch does not open and terminate the defrost cycle, the timer will terminate the defrost cycle 45 minutes after it started.

Manual Defrost Key

A Manual Defrost key is located in the cab control box. Pressing the Manual Defrost key initiat es the defrost cycle if the defrost termination switch is closed.

Defrost Termination Switch

The electronic defrost termination switch uses solid state components to control the defrost circuit. The switch is mounted in the evaporator and controls the defrost cycle in response to the evaporator coil temperature. The switch is closed when the evaporator coil temperature is below 42 F

1. Defrost Termination Switch 3. Screw Terminal

2. 12 Wire 4. Ground Wire

Defrost Termination Switch

Page 44

Electrical Maintenance (Rev 1/99)

Defrost Termination Switch Bench Test

1. Connect a test light between the screw terminal on the switch and the positive battery terminal.

NOTE: Attempting to test th e electronic defrost termination switch with an ohmmeter is generally not satisfactory because of the low voltage available at the meter leads.

2. Connect the ground wire of the switch to the negative battery terminal.

3. Raise the temperature of the defrost termination switch above 52 F (11.1 C). The light should be off, i n di cating an open switch.

4. Cool the defrost termination switch below 42 F (5.6 C). The light should come on, indicating the switch has closed.

NOTE: Allow adequate time for the temperature change to saturate the defrost termination switch before perform i ng the test.

Defrost Relay

The defrost relay controls the operation of the defrost cycle. When the defrost timer or the Manual Defrost key completes the circuit through the defrost termin ation switch to ground, the defrost relay is energized. This energizes the hot gas solenoid and de- energizes the fan relay. The defrost relay stays energized until the defrost cycle is terminated by the defrost termination switch or the defrost timer.

Hot Gas Solenoid

The hot gas solenoid is a normally closed solenoid valve that controls the flow of refrigerant thro ugh the refri gerat ion system. The hot gas solenoid opens when it is energized by the defrost relay. This causes most of the hot gas refrigerant to bypass the condenser and flow directly to the evaporator, where it heats the evaporator coil.

V250 Defrost System and P.C. Board Identification and Testing

The V250 defrost system energizes a hot gas defrost solenoid valve (HGV) to route hot gas through the evaporator coil. This method of defrosting the evaporator coil is used for over the road operation, and for electric operation on units equipped with electric standby.

The electrical controls in the defrost system consist of the following items:

1. The manual defrost switch and defrost LED located in cab control box.

2. The defrost termination switch (ETS) mounted on the evaporator coil.

3. The printed circuit (P.C.) board located in the low voltage box in the condenser.

4. The associated wiring.

Pressing the manual defrost switch in the cab control box applies 12 volts to the 11 circuit, which is connected to the P.C. board in the low vo ltage box. The defrost LED is energized through the 11 circuit and grounded through the 12 circuit.

The defrost termination switch grounds the 12 circuit to a chassis ground when it closes. The defrost termination switch closes when the temperature drops below 42 F. It opens when the temperature rises above 52 F.

The P.C. board contains the following items that are part of the defrost system:

1. The defrost relay (DR).

2. The defrost relay LED (PL7).

3. The timing chip for the timed defrost interval (defrost initiation timer).

4. The adjustable potentiometer (R16/R17) used to adjust the timed defrost interval.

5. The fast clock jumper (W2) used to speed up the timed defrost interval for testing.

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Electrical Maintenance (Rev 1/99)

6. The timing chip for the maximum defrost time limit (defrost termination timer), which is set at 45 minutes.

7. The fast clock jumper (W1) used to speed up the maximum defrost time limit for testing.

Manual defrost is selected by pressing the manual defrost switch. This applies 12 volts to the 11 circuit, which is connected to the 85 pin of the defrost relay coil. The 86 pin of the defrost relay coil is connected to the 12A circuit. The 12A circuit is connected to the 12 circuit through th e timer for the maximum defrost time limit. If the 12 circuit is grounded through a closed defrost termination switch, the defrost relay will energize and pull in.

When the defrost relay is energized, it closes a set of contacts that connect the 8B (power) circuit to the 26 circuit. This energizes the hot gas valve. When the defrost relay is energized, it also opens a set of contacts that connect the 8B (power) circuit to the 26D circuit. This de-energ izes the fan relay to stop the condenser and evaporator fans. Once energized, the defrost relay coil is held in by a latching circuit that consists of a diode (D20) connecting the 26 circuit to the 11 circuit.

The unit will remain in defrost until one of the following events occurs:

1. The defrost termination switch opens and removes the ground from the 12 circuit. This de-energizes the defrost relay.

2. The unit is turned off.

3. The 45 minute maximum defrost time limit is reached and the timer opens the connection between the 12 and 12A circuits. This removes the ground from the 12A circuit to de-energize the defrost relay.

The timer for the maximum defrost time limit controls a transistor that acts like a set of relay contacts connecting the 12 circuit to the 12A circuit. Jumper W1 is used to fast clock this timer to approximately 1.5 minutes for testing.

The timed defrost interval timer can be adjusted from 1 to 10 hours by placing the dial on the p otenti ometer (R1 6/R17) in the desired position. The factor y setting is 4 hours. The timer is powered by the 2 circuit, but it does not start to time until the unit is running and the defrost termination switch is

closed. The timer retains the accumulated time when the unit shifts to null or when the unit is turned off. When the timer accumulates 4 hours, it applies 12 volts to the 11/ DRF-DR circuit. This energizes the defrost relay to start defrost. The timer resets to zero and starts over whenever 12 volts are present on the 11 circuit. J umper W2 is used to f ast clock this timer to approximately 1 minute for testing.

P.C. Board Identification

Currently, three differe nt P.C. boards have been use d on th e V250.

• The first version, P/N 41-776, has four fuses.

• The second version, P/N 41-1619, has five fuses.

• The third version, P/N 41-1812, also has five fuses, but

uses a different arrangement for jumpers W1 and W2. The fast clock jumper pins for W1 and W2 are located in the same positions, but the standar d (parked) positions for these jumpers are identified as W3 and W4 and are located below potentiometer R17.

A significant electrical change was made between the first version and second version. Opening the high pressure cutout (HPCO) or the low pressure cutout (LPCO) de-energizes the power relay PR on the first version. Opening the HPCO or the LPCO de-energizes the circuit to the compressor clutch on the second and third versions.

A P.C. board i s identified by its Service Part Nu mber (P/N or SP#), which is located to the left of the potentiometer R16/R17. The P.C. board must be correctly identified to determine which wiring schematics and diagrams to use when troubleshooting the electrical system.

• For the first version, P/N 41-776, use 5D44455 and 5D44456.

• For the second version, P/N 41-1619, and the third version, P/N 41-1812, use 5D46179 and 5D46190.

NOTE: The nameplate on the cover of the low voltage box does not necessarily identify the P.C. board correctly. The P.C. board must be identified by looking at its part number.

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Electrical Maintenance (Rev 1/99)

AGA406

1. Defrost Relay 4. Jumper W2 Defrost Initiation Timer

2. Defrost LED PL7 5. Potentiometer R17

3. Jumper W1 Defrost Termination Timer 6. Service Part Number

P.C. Board P/N 41-776 (First Version)

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Electrical Maintenance (Rev 1/99)

AGA407

1. Defrost Relay 5. Jumper W2 Defrost Initiation Timer

2. Defrost LED PL7 6. Potentiometer R17

3. Jumper W1 Defrost Termination Timer 7. Service Part Number

4. Defrost Fuse F5

P.C. Board P/N 41-1619 (Second Version)

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Electrical Maintenance (Rev 1/99)

AGA408

1. Defrost Relay 5. Jumper W2 Defrost Initiation Timer

2. Defrost LED PL7 6. Potentiometer R17

3. Jumper W1 Defrost Termination Timer 7. Standard (Parked) Jumper Position

4. Defrost Fuse F5 8. Service Part Number

P.C. Board P/N 41-1812 (Third Version)

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Electrical Maintenance (Rev 1/99)

T roubleshooting the V250 Defrost System with P.C. Board P/N 41-776

Unit will not defrost when the manual defrost switch is pressed.

A. Check the defrost termination switch.

1. The defrost termination switch should be closed at temperatures below 42 F. Make sure the evaporator temperature is below 42 F.

2. Disconnect the 12 wire from the defrost termination switch and place a jumper between the 12 wire and ground. Press the manual defrost switch.

a. If the uni t goes into defrost, the defrost termi-

nation switch is probably defective and should be replaced. (NOTE: If this step is being performed as instructed by later steps in this procedure, the defrost termination swit ch may not be defective.)

b. If the unit does not defrost, go to the next step.

3. Check for voltage between J4-5 (1 2 circuit) and J 42 (CH circuit) at the P.C. board while pressing the manual defrost switch (to energize the 11 circuit).

a. If voltage (approximately 12 volts) is present,

check the 12 wire from the P.C. board to the defrost termination swi tc h for an open or sh ort circuit and repair it.

b. If no voltage is present, remove the jumper

from the 12 wire at the defrost termination switch and repeat step A.3. If voltage is now present, repeat step A.2. If voltage is still not present, go to the next step.

B. Check the P.C. Board.

nected and the 11 circuit energized, check the following:

a. Remove the defrost relay from its socket.

Check for voltage on the 11 circuit at the 85 pin of the defrost relay socket while the pressing the manual defrost swi tch.

b. If no voltage is present on the 11 circuit, go to

step B.3.

c. If voltage is present on the 11 circuit, install a

new relay in the defrost relay socket. Recheck the voltage on the 12 circuit while pressing the manual defrost switch.

If voltage is still not present on the 12 circuit, the P.C. board is probably defective and should be replaced.

If voltage is now present on the 12 circuit, go to the next step.

2. If voltage is present between J4-5 (12 circuit) and J4-2 (CH circuit) with the 12 wire disconnected from the defrost termination switch and the 11 circuit energized, check the following:

a. Ground the 12 circuit and press the manual

defrost switch.

b. The unit should go into defrost and the defrost

relay LED (PL7) should light. The defrost relay was defective.

3. If no voltage is present on the 11 circuit at the 85 pin of the defrost relay socket while pressing the manual defrost switch, check the following: Check for volta ge between J1 -11 (11 circuit - gray wire) and a chassis ground (CH circuit) at the P.C. board while pressing the manual defrost switch.

1. If no voltage is present between J4-5 (12 circuit) and J4-2 (CH circuit) with the 12 wire discon-

a. If voltage is present, the P.C. board is probably

defective and should be replaced.

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Electrical Maintenance (Rev 1/99)

b. If no voltage is present, check the wire harness

from the cab control box to the P.C. board. If the wire harness is not defective, check the cab control box (step c.).

c. Check the cab control box. Before checking

the cab control box, place a good relay in the defrost relay socket and ground the 12 wire at the defrost termination switch.

1. Check for continuity to a good chassis ground at pin 9 (CH circuit - black wire) in the connector in the back of the cab control box. This is the ground circuit for the cab control box. If this circuit does not have continuity to grou nd, check t he foll owing: the black (CH) wire in the wire harness to the P.C. board J1-8, the CH circuit on the P.C. board, and the other associated CH circuits.

2. Check for voltage (approximately 12 volts) between pin 3 (2R3 cir cui t - orange wire) and pin 9 (CH circuit - black wire) at the connector in the back of the cab control box. The 2R3 circuit is the over the road power circuit. If voltage is not present on the 2R3 circuit, check the following: the orange (2R3 ) wire in the wire har ness to the P.C. board J1-3 , the 2R3 circu it on the P.C. board, the ACC circuit on the P.C. board, and the ACC wire from the P.C. board J6-1 to the accessory terminal in the truck.

3. (Only for units equipped with electric standby) Check for voltage (approximately 12 volts) between pin 2 (2R2 circuit - red wire) and pin 9 (CH circuit - black wire) at the connector in the back of the cab control box. The 2R2 circuit is the electric standby power circuit. If voltage is not present on the 2R2 circuit, check the following: the red (2R2) wire in the wire harness to the P.C. board J1-4, the 2R2 circuit on the P.C. board, the 2R1 circuit on the P.C. board, fuse F4 on the P.C. board,

circuits X1 (J5-4) and X4 (J 5-1 ), and the rest of the electric standby power supply.

4. Check for voltage between pin 8 (11 circuit -gray wire) and pin 9 (CH circuit - black wire) in the connector in the back of the cab control box while pressing the manual defrost switch. Voltage should be present and the defrost LED (on the cab control box) should be lit.

a. If no voltage is present, the cab control box is

probably defective and should be replaced.

b. If voltage is present, go to the next step.

5. Check for voltage between pin 8 (11 circuit -gray wire) and pin 4 (12 circuit - yellow wire) in the connector in the back of the cab control box while pressing the manual defrost switch. Voltage should be present and the defrost LED should be lit.

a. If voltage is present but the defrost LED is not

lit, the cab control box is probably defective and should be replaced.

b. If no voltage is present, check the 12 circuit to

make sure it has continuity to ground and repeat steps C.4. and C.5.

Unit will defrost only when the manual defrost switch is pressed and held in.

Check for voltage (approximately 12 volts) between J3-4 (26 circuit) and a chassis ground (CH circuit) at the P.C. board while pressing the manual defrost switch.

1. If no voltage is present, replace the defrost relay with a new one and recheck the voltage on the 26 circuit while pressing the manual defrost switch.

a. If voltage is now present, the defrost relay was

defective.

b. If voltage is still not present, the P .C. board is prob-

ably defective and should be replaced.

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Electrical Maintenance (Rev 1/99)

2. If voltage is present on the 26 circuit but the unit will not stay (latch) in defrost, diode D20 or its circuit is probably defective. Replace the P.C. board or diode D20.

Hot gas valve does not energize when unit is in defrost.

Check for voltage (approximately 12 volts) at the 8A - 8B circuit also, between J3-4 (26 circuit) and J3-2 (CH circuit) at the P.C. board while the unit is in defrost.

1. If no voltage is present check the F-3 Fuse, replace if necessary.

a. If voltage is still not present, replace the defrost

relay with a new one and recheck the voltage on the 26 circuit while the unit is in defrost.

b. If voltage is still not present, replace the power

relay.

c. If voltage is now present, the power relay was

defective.

b. If the resistance is in this rang e, the h ot gas v alve is

probably defective and should be replaced.

Unit stays in defrost for only one to two minutes.

Check the position of jumper W1. If it is in the fast clock position (see the appropriate drawing), defrost will terminate approximately 1 to 2 minutes after it starts.

Defrost will not terminate on maximum time limit of approximately 45 minutes.

Use the following procedure to check the defrost termination timer. This procedure assumes the rest of the defrost system functions properly.

1. Place jumper W1 in the fast clock position (see the appropriate drawing).

2. Ground the 12 circuit.

3. Press the manual defrost switch to initiate defrost.

4. Defrost should terminate approximately 1 to 2 minutes after it starts.

d. If voltage is still not present, the P .C. board is prob-

ably defective and should be replaced.

2. If voltage is present on the 26 circuit, check the 26 circuit from the P.C. board to the hot gas valve for an open or short circuit.

3. If the 26 circuit from the P.C. board to the hot gas valve is intact, check the CH circuit from the hot gas valve to the P.C. board for an open or short circuit.

4. If the CH circuit from the hot gas valve to the P.C. board is intact, check the coil on the hot gas valve. To check the coil disconnect it from the 26 and CH circ uits and check its resistance with a good ohmmeter. The hot gas valve coil should have a resistance of 15 to 19 ohms.

a. If the resis tance is significantly out of this range,

the coil is probably defective and should be replaced.

5. If defrost does not terminate on the maximum defrost time limit, the timer is defective. The P.C. board should be replaced.

Defrost will not initiate automatically. Use the following procedure to check the def rost initiation

timer. This procedure assumes the rest of the defrost system functions properly.

1. Place jumper W2 in the fast clock position (see the appropriate drawing).

2. Ground the 12 circuit.

3. Defrost should initiate in approximately 1 to 2 minutes.

4. If defrost does initiate on the timed defrost interval, the timer is defective. The P.C. board should be replaced.

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Electrical Maintenance (Rev 1/99)

T roubleshooting the V250 Defrost System with P.C. Boards P/N 41-1619 and P/N 411812

Unit will not defrost when the manual defrost switch is pressed.

A. Check the defrost termination switch.

1. The defrost termination switch should be closed at temperatures below 42 F. Make sure the evaporator temperature is below 42 F.

2. Disconnect the 12 wire from the defrost termination switch and place a jumper between the 12 wire and ground. Press the manual defrost switch.

a. If the uni t goes into defrost, the defrost termi-

b. If the unit do es not defros t , go to the next step.

B. Check the P.C . Board.

1. Check defrost fuse F5 (1 amp). a. If fuse F5 is burnt out, replace it and perform

step A.2.

b. If fuse F5 is not b urn t ou t , g o t o t he next step.

2. If no voltage is present between P4-5 (12 circuit) and P4-2 (CH circuit) with the 12 wire disconnected and the 11 circuit energized, check the following:

a. Remove the defrost relay from its socket.

Check for voltage on the 11 circuit at the 85 pin of the defrost relay socket while the pressing the manu al defrost switch.

b. If no voltage is present on the 11 circuit, go to

step B.4.

c. If voltage is present on the 11 circuit, install a

new relay in the defrost relay socket. Recheck the voltage on the 12 circuit while pressing the manual defrost switch.

3. Check for voltage between P4-5 (12 circuit) and P4-2 (CH circuit) at the P.C. board while pressing the manual defrost switch (to energize the 11 circuit).

a. If voltage (approximately 12 volts) is present,

check the 12 wire from the P.C. board to the defrost termination swi tc h for an open or sh ort circuit and repair it.

b. If no voltage is present, remove the jumper

from the 12 wire at the defrost termination switch and repeat step A.3.

If voltage is now present, repeat step A.2. If voltage is still not present, go to the next

step.

If voltage is still not present on the 12 circuit, the P.C. board is probably defective and should be replaced.

If voltage is now present on the 12 circuit, go to the next step.

3. If voltage is present between P4-5 (12 circuit) and P4-2 (CH circuit) with the 12 wire disconnected from the defrost termination switch and the 11 circuit energized, check the following:

a. Ground the 12 circuit and press the manual

defrost switch.

b. The unit should go into defrost and the defrost

relay LED (PL7) should light. The defrost relay was defective.

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Electrical Maintenance (Rev 1/99)

4. If no voltage is present on the 11 circuit at the 85 pin of the defrost relay socket while pressing the manual defrost switch, check the following: Check for voltage between P1-11 (11 circuit - gray wire) and a chassis ground (DRF circuit) at the P.C. board while pressing the manual defrost switch.

a. If voltage is present, the P .C. board is probably

defective and should be replaced.

b. If no voltage is present, check the wire harness

from the cab control box to the P.C. board. If the wire harness is not defective, check the cab control box (step C.).

C. Check the cab control box. Before checking the cab

control box, place a good relay in the defrost relay socket and ground the 12 wire at the defrost term ination switch.

1. Check for continuity to a good chassis ground at pin 9 (CH circuit - black wire) in the connector in the back of the cab control box. This is the ground circuit for the cab control box. If this circuit does not have continuity to grou nd, check t he foll owing: the black (CH) wire in the wire harness to the P.C. board P1-8, the CH circuit on the P.C. board, and the other associated CH circuits.

2. Check for voltage (approximately 12 volts) between pin 3 (ACD circuit - orange wire) and pin 9 (CH circuit - black wire) at the connector in the back of the cab control box. The ACD circuit is the over the road power circuit. If voltage is not present on the ACD circuit, check the following: the orange (ACD) wire in the wire harness to the P.C. board P1-3, the ACD circuit on the P.C. board, the ACD circuit on the P.C. board, and the ACD and ACC wires from the P.C. board P6-1 to the accessory terminal in the truck.

3. Only for units equipped with electric standby) Check for voltage (approximately 12 volts) between pin 2 (2R1 circuit - red wire) and pin 9 (CH circuit - black wire) at the connector in the back of the cab control box. The 2R1 circuit is the electric standby power circuit. If voltage is not present on the 2R1 circuit, check the following : the red (2R1) wire in the wir e harness to the P.C. board P1-4, the 2R1 circuit on the P.C. board, fuse F4 on the P.C. board, circuits X1 (P5-4) and X2 (P5-5), and the rest of the electric standby power supply.

4. Check for voltage between pin 8 (DRF circuit gray wire) and pin 9 (CH circuit - black wire) in the connector in the back of the cab control box while pressing the manual defrost switch. Voltage should be present and the defrost LED (on the cab control box) should be lit.

a. If no voltage is present, the cab control box is

probably defective and should be replaced.

b. If voltage is present, go to the next step.

a. If voltage is present but the defrost LED is not

lit, the cab control box is probably defective and should be replaced.

b. If no voltage is present, check the 12 circuit to

make sure it has continuity to ground and repeat steps C.4. and C.5.

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Electrical Maintenance (Rev 1/99)

Unit will defrost only when the manual defrost switch is pressed and held in.

Check for voltage (approximately 12 volts) between P3-4 (26 circuit) and a chassis ground (CH circuit) at the P.C. board while pressing the manual defrost switch.

1. If no voltage is present check the F-3 Fuse, replace if necessary

2. If no voltage is present, replace the defrost relay with a new one and recheck the voltage on the 26 circuit while pressing the manual defrost switch.

a. If voltage is now present, the defrost relay was

defective.

b. If voltage is still not present, the P .C. board is prob-

ably defective and should be replaced.

3. If voltage is present on the 26 circuit but the unit will not stay (latch) in defrost, diode D20 or its circuit is probably defective. Replace the P.C. board or diode D20.

3. If the 26 circuit from the P.C. board to the hot gas valve is intact, check the CH circuit from the hot gas valve to the P.C. board for an open or short circuit.

4. If the CH circuit from the hot gas valve to the P.C. board is intact, check the coil on the hot gas valve. To check the coil disconnect it from the 26 and CH circuits and check its resistance with a good ohmmeter. The hot gas valve coil should have a resistance of 15 to 19 ohms.

a. If the resis tance is significantly out of this range,

the coil is probably defective and should be replaced.

b. If the resistance is in this rang e, the hot gas valve is

probably defective and should be replaced.

Unit stays in defrost for only one to two minutes.

Check the position of jumper W1. If it is in the fast clock position (see the appropriate drawing), defrost will terminate approximately 1 to 2 minutes after it starts.

Hot gas valve does not energize when unit is in defrost.

Check for voltage (approximately 12 volts) between P3-4 (26 circuit) and P3-2 (CH circuit) at the P.C. board while the unit is in defrost.

1. If no voltage is present, replace the defrost relay with a new one and recheck the voltage on the 26 circuit while the unit is in defrost.

a. If voltage is now present, the defrost relay was

defective.

b. If voltage is still not present, the P .C. board is prob-

ably defective and should be replaced.

2. If voltage is present on the 26 circuit, check the 26 circuit from the P.C. board to the hot gas valve for an open or short circuit.

Defrost will not terminate on maximum time limit of approximately 45 minutes.

Use the following procedure to check the defrost termination timer. This procedure assumes the rest of the defrost system functions properly.

1. Place jumper W1 in the fast clock position (see the appropriate drawing).

2. Ground the 12 circui t.

3. Press the manual defrost switch to initiate defrost.

4. Defrost should terminate approximately 1 to 2 minutes after it starts.

5. If defros t does not term inate on the m aximum defros t time limit, the timer is defective. The P.C. board should be replaced.

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Electrical Maintenance (Rev 1/99)

Defrost will not initiate automatically.

Use the following procedure to check the def rost initiation timer. This procedure assumes the rest of the defrost system functions properly.

1. Place jumper W2 in the fast clock position (see the appropriate drawing).

2. Ground the 12 circuit.

3. Defrost should initiate in approximately 1 to 2 minutes.

4. If defrost does initiate on the timed defrost interval, the timer is defective. The P.C. board should be replaced.

P.C. Board P/N 41-776 Test Procedure

1. Connect a 12 volt DC power supply, positive to GS1 stud hole (2 circuit) and negative to GS3 stud hole (CH circuit).

2. Connect 12 volt positive to pin 1 of co nnector J6 (ACC circuit).

3. Connect pin 3 and pin 5 of connector J4 together (this connects 12 to CH).

4. Connect pin 1 of connector J2 and pin 1 of connector J 4 together (this connects 7 to 7B).

5. Plug the cab box into the P.C. board with the cab box harness.

6. Connect a variable resi st ance (6 20 t o 120 0 oh ms) to the two pin connector on the cab box harness (this simulates the thermostat sensor).

7. Plug in the six relays as specified on the board.

8. Replace any fuses that are missing or blown.

9. With the power supply turned on and the cab box turned off, PL3 only should light.

10. Turn cab box on a nd turn the set point to “00” degrees.

11. Turn the variable resistance until the cab box shows “05” degrees.

12. LEDs PL1, 2, 3, 5, 8, and 11 should light as well as the LED in the cab box display between the digits at the top of the display and the snowflake LED.

13. Turn variable resistance until the cab box shows “00” degrees.

14. All LEDs except PL3 should go off.

15. Turn the variable resistance until the cab box shows “-05” degrees.

16. LEDs PL1, 2, 3, 5, and 9 should light as well as the LED in the cab box display to the top left of the digits.

17. Jumper on W2 away from J1, and turn R16 fully counter clockwise.

18. Turn the variable resistance until the cab box shows “05” degrees.

19. In about 1 minute the circuit should go into th e defrost mode. In this mode LEDs P L3 , 7, 8, and 11 should light as well as the defrost indicator on Move the jumper on W1 toward connector J1, the cab box.

20. In another minute and 15 seconds the circuit should come out of the defrost mode. LEDs PL1, 2, 3, 5, 8, and 11 should light.

21. Turn cab box and power supply off.

22. Disconnect pin 1 of connector J6 from the positive side of the power supply. Connect pin 4 (or 5) of connector J5 and stud hole GS2 to positive.

23. Turn power supply and cab box on.

24. With cab box display showing “05” degrees LEDs P11, 2, 3, 5, 6, 8, and 10 should light as well as the power cord indicator on the cab box.

25. When circuit goes into the defrost mode LEDs PL3, 6, 7, 8, and 10 should light.

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Electrical Maintenance (Rev 1/99)

26. Turn variable resistance until the cab box shows “00” degrees.

27. LEDs PL3 and 6 should light.

28. Turn the variable resistance until the cab box shows “-05” degrees.

29. LEDs PL3, 4, and 6 should light as well as the top left LED in the cab box display.

30. Turn off the cab box and po wer supp ly. Move jumpers on W1 and W2 to the opposite positions. Turn R16 to position #3.

This test will checkout most circuits on the board. It will not test a circuit that may be broken or burned out between the relays and all the connector pins that were not connected to in this test. To test these, a volt meter or external lights would have to be connected to each pin and observ ed for the proper results.

P.C. Board P/N 41-1812 and P/N 41-1619

Test Procedure

1. Connect a 12 volt DC power supply, positive to GS1 stud hole (2 circuit) and negative to GS3 stud hole (CH circuit).

2. Connect 12 volt positiv e to pin 1 of con nector P6 (ACD circuit).

3. Connect pin 3 and pin 5 of connector P4 together (this connects 12 to CH).

4. Connect pin 1 of connector P2 and pin 1 of connector P4 together (this connects 8B to 8HA).

7. Plug in the six relays as specified on the board.

8. Replace any fuses that are missing or blown.

9. With the power supply turned on and the cab box turned off, PL3 only should light.

10. Turn cab box on and turn the setpoint to “00” degrees.

11. Turn the variable resistance until the cab box shows “05” degrees.

12. LEDs PL1, 2 , 3, 5 , 8, an d 11 shoul d l ig h t as w el l as t he LED in the cab box display between the digits at the top of the display and the snowflake LED.

13. Turn variable resistance until the cab box shows “00” degrees.

14. All LEDs except PL3 should go off.

15. Turn the variable resistance until the cab box shows “-05” degrees.

16. LEDs PL1, 2, 3, 5, and 9 should light as well as the LED in the cab box display to the top left of the digits.

17. Move the jumpers from W3 and W4 to W1 and W2 positions and turn R17 fully counter clockwise.

18. Turn the variable resistance until the cab box shows “05” degrees.

19. In about 1 minute the circuit should go into th e defrost mode. In this mode LEDs P L3 , 7, 8, and 11 should light as well as the defrost indicator on the cab box.

20. In another minute and 15 seconds the circuit should come out of the defrost mode. LEDs P L1, 2, 3, 5, 8, and 11 should light.

5. Plug the cab box into the P.C. board with the cab box harness.

6. Connect a variable resi st ance (6 20 t o 120 0 oh ms) to the two pin connector on the cab box harness (this simulates the thermostat sensor).

21. Turn cab box and power supply off.

22. Disconnect pin 1 of connector P6 from the positive side of the power supply. Connect pin 4 (or 5) of connector P5 and stud hole GS2 to positive.

23. Turn power supply and cab box on.

Page 57

Electrical Maintenance (Rev 1/99)

24. With cab box display showing “05” degrees LEDs P11, 2, 3, 5, 6, 8, and 10 should light as well as the power cord indicator on the cab box.

25. When circuit goes into the defrost mode LEDs PL3, 6, 7, 8, and 10 should light.

26. Turn variable resistance until the cab box shows “00” degrees.

27. LEDs PL3 and 6 should light.

28. Turn the variable resistance until the cab box shows “- 05” degrees.

29. LEDs PL3, 4, and 6 should light as well as the top left LED in the cab box display.

30. Turn off the cab box and po wer supp ly. Move jumpers from W1 and W2 to W3 and W4. Turn R17 to position #3.

6. With all switches off, apply power to the circuit.

7. With the cab box On/Off switch off, no lights should come on.

8. Turn on the cab box On/Off switch. The temperature display should come on.

9. Press the setpoint key once and adjust the setpoint to “00” degrees.

10. Turn the variable resistance so that temperature read out is “00” degrees.

11. Only the display, the C or F LED, and the LED in the ON/OFF switch should be on at this time.

12. Close switch S1 to pin 2. The power cord LED should come on and PL1 connected to pin 1.

13. Turn variable resistance to indicate 5 degrees on display.

14. PL2 connected to pin 6 and the LED at the top of the display between the digits on the cab box should come on.

15. Close switch S4 to pin 7. The snowflake LED on the cab box should come on.

M10 (V250/V-090) Cab Control Box Test Procedure

1. Connect +12 Vdc Power to pin 3 and negative ground to pin 9.

2. Connect light bulbs or LEDs between ground and pins 1, 6, and 8.

3. Connect a light bulb or LED between +12 Vdc and pin

10.

4. Connect switches between +12 Vdc and pins 2, 4, 5, and 7.

5. Connect a variable resistance (620 to 1 12 0 ohm s) to the 2 pin sensor connector.

16. Close switch S2 to pin 4 and switch S4 to pin 7.

17. Press the defrost key on the cab box. PL3 connected to pin 8 and the defrost LED on the cab box should come on but only while this key is being held.

18. Turn the variable resistance to indicate -5 degrees on the display and open switch S4 to pin 7.

19. PL2 should go off and PL4 connected to pin 10 should come on. The snowflake LED and the LED at the top of display between the digits should go off, and the LED at the top of the display to the left of the digits should come on.

20. Close switch S3 to pin 5. Thi s shou ld cause the cab bo x to shut off and the alarm symbol LED to come on.

Page 58

Electrical Maintenance (Rev 1/99)

AGA409

M10 Cab Control Box Test Circuit

Page 59

Electrical Maintenance (Rev 1/99)

CONDENSER FAN PRESSURE SWITCH (CFPS)

The CFPS is located in the discharge line. Electricall y it is located between F1 and the condenser f an motor. It closes to energize the condenser fan when the heat pressure rises to 180 ± 10 psi (1241 ± 69 kPa). It opens to de-energize the condenser fan when the head pressure drops to 130 ± 10 psi (896 ± 69 kPa). To check the CFPS:

1. Install a manifold gauge set.

2. Connect a voltmeter between F3 and the condenser fan where the CFPS wires are connected to the main wire harness.

3. Run the unit on cool, check the voltmeter reading, and watch the condenser fan.

a. When the head pressure is below 180 ± 10 psi

(1241 ± 69 kPa), the CFPS should be open, the voltmeter should indicate battery voltage, and the condenser fan should not be running.

If the voltage is low and the condenser fan is running, the CFPS is defective.

AC COMPONENTS (Model 20)

CAUTION: The unit uses high voltage alterna ting

current (ac) during electric operation. Lethal voltage potentials can exist on connections in the high voltage box. Take appropriate precautions and use extreme care when testing the unit.

Contactors

T est the contact points of the cont actor by checking the voltage drop across each set of points when the contactor is energized and the system is operating. If the voltage drop across a set of points is more than 15 volts ac, replace the contactor.

Test the contactor coil by checking the voltage across the coil. The contactor coil should be energized by a minimum of 10 volts dc.

Overload Relay

The overload relay should open if the motor circuit current draw is more than overload relay setting lis ted in the Sp ecifications chapter.

If the voltage is low and the condenser fan is not running, check the power circuit back through the fan relay to the battery. Also check the ground circuit (CH) back to the battery.

b. When the head pressure rises above 180 ± 10 psi

(1241 ± 69 kPa), the CFPS should close, the voltmeter should indicate no voltage, and the condenser fan should be running.

c. When the head pressure drops below 130 ± 10 psi

(896 ± 69 kPa), the CFPS should open, the voltmeter should indicate battery voltage, and the condenser fan should not be running.

If the CFPS does not open or close at the proper pressures, it is defective and must be replaced.

ELECTRIC ST ANDBY CIRCUITS (Model 20 Only)

Make sure the unit is connected to the proper power source. The current draw through the compressor motor should not exceed the full load current listed in the Specifications.

The dc current draw through the 2 wire should not exceed 30 amps in 12 volt systems and 20 amps in 24 volt systems.

If the DC current is excessive, check the current draw through each fan motor. The current draw through an individual fan motor should not exceed the full load current listed in the Specifications.

If the fan motor currents are satisfactory, check the control relays and switches for shorts.

Page 60

Electrical Maintenance (Rev 1/99)

When the unit is inoperative, follow a systematic checking sequence. This will save time and eliminate guesswork.

Check the power cable receptacle for power. If power is present, check for power at the unit terminal board.

Check for control circuit power at the circuit breaker. If the contactor is pulled down but the compressor motor fails to start, the trouble is probably in the compressor motor assembly.

12 Volt System

The dc voltage should be 12.5 to 13 volts and the current through the 2R wire should be less than 25 amps. If the current is less than 25 amps and the voltage is less than 12 volts:

1. Check the ac line voltage the transformer fuse. The line voltage must be at least 90% of the voltage specified for the unit. if the ac line voltage is acceptable and the transformer fuse is intact, go to step 2.

2. Measure the transformer output voltage (ac) at the rectifier between wires X1 and X4. If the transformer output voltage is between 12 to 13 volts ac no load, it is ok. If the transformer output voltage is acceptable, go to step 3.

3. Check the rectifier output voltage (dc) on the 2R wires at the terminal board.

If the rectifier output voltage is less than 13 Vdc and the load is not excessive (not more than 25 amps), the rectifier is defective.

EVAPORATOR HEATERS (Optional)

Test the resistance of each evaporator heater by disconnecting it from the circuit and checking it with an ohmmeter. The resistance of each heater should be approximately 70 ohms.

Page 61

Refrigeration Maintenance

NOTE: The following procedures involve servicing the refrigeration system. Some of these service procedures are regulated by Federal, and in some cases, by State and Local laws.

All regulated refrigeration service procedures must be performed by an EPA certified technician, using approved equipment and complying with all Federal, State and Local laws.

REFRIGERANT CHARGE

Charging the Refrigeration System

The receiver tank sight glass allows the operator to determine the amount of charge under established operating conditions. These units can be damaged by an over-charge of refrigerant. The amount of refrigerant the system can hold depends on circuit volume which is affected by hose length. The most satisfactory method of charging the engine-driven compressor circuit and the electric standby driven compressor circuit is:

1. Connect a gauge manifold to the engine-driven compressor and receiver tank.

2. Connect the center hose of the gauge manifold to the manifold of an evacuation station.

3. Connect the hose from a drum of refrigerant to the manifold of the evacuation station. Make sure the valve on the refrigerant drum is closed.

4. Open the valves on the gauge manifold and the valves on the evacuation station.

5. Start the vacuum pump and evacuate the system to 500 microns. After the system reaches 500 microns, evacuate the system for an additional hour.

NOTE: If the system will not come down to 500 microns, there is probably a leak in the system or in the evacuation and charging equipment hoses. Find and repair the leak.

Evacuate System

6. After the additional hour of evacuation, close the valve at the evacuation pump, stop the vacuum pump, and observe the reading on the vacuum gauge for 5 minutes. The pressure should not exceed 2000 microns.

NOTE: If it do es, repeat st eps 4 and 5. T his time if the pressure exceeds 2000 microns within 5 minutes, look for a leak in the system or in the evacuation and charging equipment hoses. Find and repair the leak.

7. Open the vacuum valve at the vacuum pump, start the vacuum pump, and evacuate the system to 500 micr ons.

8. When the system reaches 500 microns, close the vacuum valve at the evacuation station manifold. The system is now ready to charge.

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Refrigeration Maintenance (Rev 1/99)

9. Close the low side valve on the gauge manifold, leave the high side valve on the gauge manifold open, and open the valve on the refrigerant drum to deliver liquid.

10. Allow 5 lb (2.3 kg) of refrigerant to enter the system. Then close the valve on the refrigerant drum and the high side valve on the gauge manifold.

13. With these conditions established, open the low side valve on the gauge manifold and open the valve on the refrigerant drum to deliver liquid.

Add Liquid Refrigerant

11. Start the unit on engine operation, set the thermostat at 0 F (-20 C), and run the unit in cool until the box temperature approaches 0 F (-20 C).

12. Make sure that the unit is running in cool, the compressor is running at approximately 1000 rpm, the suction pressure is 2 to 8 psi (14 to 55 kPa), and the head pressure is at least 180 psi (1241 kPa) for R-134a systems and 275 psi (1896 kPa) for R-404A. If necessary, raise the head pressure by covering the condenser.

Finish Charging With Liquid

14. Observe the receiver tank sight glass. When the ball in the receiver tank sight glass reaches the top of the sight glass, close the valve on the refrigerant drum.

15. Close the low side valve on the gauge manifold and operate the unit for 15 minutes.

16. Model 20 only. a. Turn the unit OFF and shut off the truck engine. b. Connect the electric power receptacle to an appro-

priate electric power supply. Start and run the unit in cool on electric operation for a minimum of 15 minutes.

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Refrigeration Maintenance (Rev 1/99)

18. Stop the unit , shu t OFF the tru ck en gine and r emov e the gauge manifold set.

19. The above conditions MUST be established each time the refrigerant level is checked or if refrigerant needs to be added for any reason.

NOTE: To prevent oil migration from one compressor to another, and for proper oil return when a compressor is operating, operate a compressor for a minimum of 15 minutes. Do not operate the compressor for sho rter intervals.

Checking the Refrigerant Charge

If the unit has an insufficient charge of refrigerant, the evaporator will be “starved” and the box temperature will rise even though the unit is operating. Also, an insufficient charge does not circulate enough oil to properly lubricate the compressor. The charge may be determined by inspection of the refrigerant through the receiver tank sight glass with the following conditions established:

Run On Electric Operation

c. Turn the unit OFF and disconnect the electric

power supply. Start the truck and run the unit in cool on engine operation for a minimum of 15 minutes.

17. Check the receiver tank sigh t glass with the u nit running in cool, the box temperature at 0 F (-20 C), and a head pressure of at least 180 psi (1241 kPa) for R-134a systems and 275 psi (1896 kPa) for R-404A systems. The ball should be at the top of the sight glass.

If not, open the valve on the refrigerant drum to delivery liquid and open the low side valve on the gauge manifold. Add refrigerant liquid until the ball in the receiver tank sight glass reaches the top of the sight glass, then close the valve on the refrigerant drum and close the low side valve on the gauge manifold.

T esting the Refrigerant Charge with an Empty Box

1. Place a test box over the evaporator.

2. Install a gauge manifold set.

3. Run the unit in cool on engine operation until the thermometer reads 0 F (-18 C). By allowing the box to leak a small amount, you will be able to maintain 0 F (-18 C).

4. The discharge or head pressure gauge sh oul d be at least 180 psi (1241 kPa) on the gauge manifold for R-134a systems and 275 psi (1896 kPa) for R-404A syst em s.

If the pressure is below this, it can be raised by covering a portion of the condenser grille with a piece of cardboard.

5. Under these conditions the ball should be at the top of the sight glass to indicate a full charge.

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Refrigeration Maintenance (Rev 1/99)

Testing the Refrigerant Charge with a Loaded Box

1. Install a gauge manifold.

2. Run the unit in cool on engine operation.

3. Cover the condenser to drive any excess refrigerant from the condenser into the receiver tank.

4. As the head pressure rises, check the r eceiver tan k sight glass. If there is no indication of refrigerant in the receiver tank sight glass, indicated by the float ball being down in the bottom sight glas s, the unit contains less than a full charge and more refrigerant MUST be added. Refer to Charging the Refrigeration System to add refrigerant.

CHECKING COMPRESSOR OIL CHARGE

The compressors are furnished with the amount of oil shown in the Specifications chapter. The oil level in the compressor will change after the compressor is initially run, making any level measurements inaccurate.

To ensure an adequate oil supply, the following procedure must be followed whenever the refrigerant charge is lost or removed from a unit:

1. Install a compressor on the system having a residual oil supply and self-lubricating system such as a TK 214 model. Connect an oil separator on the discharge or suction line to collect and drain out circulated oil.

NOTE: A suction line oil s eparat or ca n be i mprovis ed by installing a suction filter up side down in the suction line near the compressor. Cap off both access ports, and use the lower one to drain off the accumulated oil.

4. Operate at a low speed (600 to 800 rpm) for 2 hours, or until the compressor oil level reaches a minimum allowable level, whichever occurs first. Drain the collected oil from the oil separator as it fills, taking care to not allow any collected oil to recirculate.

5. Prepare the original compressor that was removed from the unit (or a replacement) by draining out any existing oil and replacing the oil with the amount of oil shown in the Specifications chapter.

6. Install the original compressor (or its replacement), and proceed with the manual evacuation and refrigerant charging procedure. Char ge to normal amoun t of refrigerant 5 lb (2.3 kg).

HIGH PRESSURE CUTOUT SWITCH (HPCO)

The HPCO is located on the receiver tank. If the discharge pressure rises above 350 psi (2413 kPa) for R-134a systems or 470 psi (3241kPa) for R-404A systems, the HPCO deenergizes the power relay.

NOTE: This operation is for units with printed circuit board manufactured prio r to 3-25-9 6 (see “P.C. Board P/N 41-776 (First Version)” on page 38).

When the HPCO opens on models using printed circuit board manufactured between 3-26-96 and 5-21-96, see “P.C. Board P/N 41-1619 (Second Version)” on page 39 or after 5-21-96 (see “P.C. Board P/N 41-1812 (Third Version)” on page 40) the HPCO will cycle the compressor clutch only.

To test the HPCO, rework a gauge manifold per the High Pressure Cutout Manifold illustr a tion.

2. Place a normal amount of oil in the cleanup compressor before operating.

3. Charge with 6.0 to 7.0 lb (2.7 to 3.2 kg) of refrigerant.

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Refrigeration Maintenance (Rev 1/99)

4. Failure of the high pressure cutout system to stop compressor operation should be investigated first by checking the control circuit operation and second by replacing the HPCO.

LOW PRESSURE CUTOUT SWITCH (LPCO)

The low pressure cutout switch is located on the suction line in the evaporator. If the suction pressure drops below 5 to 11 in. Hg of vacuum (-17 to -37 kPa), it opens the circuit to the power relay to stop the unit. To check the low pressure cutout:

1. Install a gauge manifold at the compressor.

1. Relief Valve (66-7392)

2. O-Ring (33-1015)

3. Adapter Tee Weather Head (No. 552X3)

High Pressure Cutout Manifold

1. Connect the gauge manifold to the compressor discharge service valve.

NOTE: Service manifold hoses must have Schrader valve (tire valve) depressors.

2. Set the thermostat well below the box temperature so that the unit will be in cool.

3. Raise the discharge pressure of the compressor first by blocking the condenser coil air flow.

2. Close the receiver tank outlet valve and run the unit in cool.

3. When the suction pressure drops below 5 to 11 in. Hg of vacuum (-17 to -37 kPa), the LPCO should open and the unit should stop.

NOTE: This operation is for units with printed circuit board manufactured prio r to 3-2 5-96 (see “P.C. Board P/N 41-776 (First Version)” on page 38).

When the LPCO opens on models using printed circuit board manufactured between 3-26-96 and 5-21-96, see “P.C. Board P/N 41-1619 (Second Version)” on page 39 or after 5-21-96 (see “P.C. Board P/N 41-1812 (Third Version)” on page 40) and th e LPCO will cycle the co mpressor clutch only.

NOTE: The discharge pressure should never be allowed to exceed a pressure of 400 psi (2758 kPa) when using R-134a and 475 psi when using R-404A.

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Refrigeration Maintenance (Rev 1/99)

CLEANUP PROCEDURE FOR SMALL TRUCK UNITS

Tools Required:

• Motor-driven TK 214 “Flushing Co mpressor”

• Suction Line Filter (P/N 204-498 with Filter P/N 66-

2988)

• Pipes (In Place of Oil Separator, Check Valve, Oil Separator and Standby Compressor)

Clean-up Procedure

1. Make sure all hose routing is correct.

2. Make sure that the oil trap is correctly installed.

3. Recover contaminated refrigerant from system.

4. Remove lines from compresso rs road si de and stand by).

5. Flush each compressor using the flushing compressor and an HFC refrigerant. (Always recover the refrigerant before disconnecting flushing compressor.)

6. Remove check valve (or check valve seats) from system to ensure flow in all directions.

1. Remove Internal Parts From Expansion Valve

2. Disconnect and Cap (If So Equipped)

3. Replace Drier With Tube

4. Discharge Line

5. Flushing Compressor

6. Suction Line

7. Suction Oil

8. Recovered Oil

Connecting Flushing Compressor to Unit

NOTE: If a Van Steenburgh reclaimer is available, do not use this procedure. Follow procedure described in Service Bulletin T&T 134.

7. Remove oil separator and install a connecting pipe.

8. Remove internals from expansion valve.

9. Open suction pressure regulator (CPR) valve to highest setting.

10. Install temporary suction line filter (P/N 204-498 and P/N 66-2988) in suction line.

11. Install connecting pipe in place of standby compressor.

12. Connect flushing system to roadside suction line (see illustration).

13. Evacuate the system and check for leaks. Continue to evacuate to remove moisture and air.

14. Install HFC refrigerant and flush the system. (Energize defrost solenoid during 30% to 40% of the clean-up. Solid contaminants will collect in the suction line filter. Oil from the system and from the flushing compressor

discharge and

Page 67

will drain out of the suction line filter. (Add compressor oil as required.) Refrigerant oil in the flushing compressor will absorb acids from the system.

15. Test compressor oil for acid contamination.

16. Continue flushing until compressor oil is clean.

Putting the Unit Back Into Operation

1. Replace check valve (or check valve seats).

2. Install new oil separator.

3. Install new liquid injection orifice.

4. Install new drier.

Refrigeration Maintenance (Rev 1/99)

5. Install ne w expansion valve.

6. Install compressors and lines.

7. Use dry nitrogen to pressurize system to 150 psi (1034 kPa).

8. Use bubble solution to check for leaks.

9. Install correct amount of oil.

10. If no leaks, evacuate unit. A leak-free and dry unit will maintain a 1000 micron vacuum for five minutes or longer.

11. Charge unit with proper amount of the correct refrigerant.

12. Operate and check for proper operatio n. (Adj ust su ction pressure re gulator.)

13. After t wo weeks of operation, change the drier.

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Refrigeration Service Operations

NOTE: It is generally good practice to rep lace the filter drier whenever the high side is op ened or when the low side is opened for an extended period of time.

COMPRESSOR

Removal

1. Remove the refrigerant charge from the system.

2. Loosen the drive belt adjuster and remove the compressor drive belt.

3. Disconnect the discharge, suction and liquid injection hoses.

1. Electric Standby Compressor (Model 20 Only) 7. Condenser Pressure Switch

2. Hot Gas Solenoid 8. Liquid Injection Solen oid

3. Drier 9. Oil Separator

4. Fuse Plug and Oil Fill Hole 10. Condenser Coil

5. Receiver Tank 11. Check Valve Assembly (Model 20 Only)

6. High Pressure Cutout Switch

Condenser Comp on ents

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Refrigeration Service Operations (Rev 1/99)

4. Keep the compressor ports and the suction and discharge lines for the compressor covered to prevent contamination of system components.

5. Remove the compressor mou nti ng s crews . Remo ve t he compressor.

Installation

NOTE: Any compressor installed in this system must contain the proper amount of compressor oil (see the Specifications section). Always check to make sure that the compressor contains the proper amount of oil. Follow the system cleanup procedures to remove old oil from the system.

1. Place the compressor in position and install the mounting screws and the belt.

2. Use belt tension tool P/N 204-427 to adjust belt tension. The engine/compressor belt tension should be adjusted to 58 on the gauge; the electric motor/compressor belt should be adjusted to 57.

3. Connect th e refrigera tion hoses. Pour 2 oz ( 59 ml) of compressor oil into the suction hose before installation.

4. Pressurize the system and test for leaks.

5. Evacuate the system and recharge.

Installation

1. Clean the tubes for soldering.

2. Place the coil in the unit and install the mounting hardware.

3. Solder the inlet and liquid line connections.

4. Pressurize the system and test for leaks.

5. Evacuate the system.

6. Recharge the unit.

7. Reinstall the cover.

DRIER

Removal

1. Pump down the refrigeration system and equalize the pressure to sligh tly positive.

2. Disconne ct the ORS nuts at the ends of the dr i er.

3. Loosen the mounting hardware and remove the drier.

Installation

1. Place new O-rings in the ORS fittin gs on the ends of the drier.

CONDENSER COIL

Removal

1. Remove the refrigerant charge.

2. Remove the condenser cover.

3. Unsolder the inlet and liquid lines.

4. Remove the mounting hardware.

5. Remove the condenser coil.

2. Install the new drier and tighten the mounting screws and nuts.

3. Install and tighten the inlet ORS nut. Hold the drier with a back-up wrench on the hex behind the ORS fitting.

4. Release a small amount of refrigerant to purge the air through the drier, and then tighten the outlet ORS nut.

5. Pressurize the system and inspect for leaks. If no leaks are found, open the refrigeration valves and place the unit in operation.

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Refrigeration Service Operations (Rev 1/99)

RECEIVER TANK

Removal

1. Remove the refrigerant charge.

2. Disconnect the refrigerant lines from the receiver tank.

3. Remove the mounting cl amp.

4. Remove the receiver tank.

Installation

1. Position the receiver tank in the unit and install the mounting clamp.

2. Connect the refrigerant lines to the receiver tank.

3. Pressurize the refrigeration system and check for leaks.

4. If no leaks are found, evacuate the system.

5. Recharge the unit.

HIGH PRESSURE CUTOUT AND CONDENSER FAN PRESSURE SWITCHES

Removal

1. Remove the refrigerant charge.

2. Remove the coil and disassemble the valve.

3. Unsolder the hot gas lines from the valve, and remove the valve from the unit.

CAUTION: Use a heat sink to prevent damaging the valve.

Installation

1. Clean the tubes for soldering.

2. Remove the coil, disassemble the valve, and place the valve in position.

3. Solder the inlet and outlet connections. After the valve cools, assemble the valve and install the coil.

CAUTION: Use a heat sink to prevent damaging the valve.

4. Pressurize the refrigeration system and test for leaks.

5. If no leaks are found, evacuate the system.

Removal

1. Remove the refrigerant charge.

2. Disconnect the wires and remove the switch.

Installation

1. Apply a refrigerant locktite to the threads of the switch.

2. Install and tighten the switch and reconnect the wires.

3. Pressurize the refrigeration system and test for leaks.

4. If no leaks are found, charge the system.

HOT GAS SOLENOID VALVE

NOTE: Valves that have nylon seats must be disassembled before soldering.

6. Recharge the unit with the proper refrigerant.

LIQUID INJECTION SOLENOID V A LVE

Removal

1. Pump down the low side and equalize the pressure to slightly positive.

2. Remove the coil from the solenoid valve.

3. Remove the solenoid valve from the receiver tank.

Installation

1. Remove the coil from the solenoid valve.

2. Install the solenoid valve on the receiver tank.

3. Connect the refrigerant line to the solenoid valve.

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Refrigeration Service Operations (Rev 1/99)

4. Install the coil on the solenoid valve and connect the wires.

5. Open the refrigerat ion valves.

OIL SEPARATOR

Removal

1. Remove the refrigerant charge.

2. Disconnect the ORS nuts at the end of the oil separator.

3. Loosen the mounting hardware and remove the oil separator.

Installation

1. Soak new o-rings in refrigerant oil (same type that is used in the system) and place the new rings in the ORS fittings on the ends of the oil separator.

2. Install and tighten the inlet and outlet ORS nut.

3. Hold the oil separator with a backup wrench on the hex behind the ORS fitting.

4. Pressurize the refrigerant system and check for leaks.

6. Recharge the unit.

1. 1/4 Flare (w/Permanent Depressor)

2. 1/4 Flare SAE 45° Flare (TYP)

NOTE: Used when oil separator is routed to evaporator section for testing. Use as a tool only. do not leave in unit.

Tee-Fitting for V250 Suction Line Access

5. If no leaks are found, evacuate the system.

LIQUID INJECTION METERING ORIFICE

Removal

1. Pump down the low side and equalize the pressure to slightly positive.

2. Disconnect the refrigeration hose from the metering orifice and remove the metering orifice from the suction hose fitting.

NOTE: Take caution to avoid the danger of liquid refrigerant escaping when the line is disconnected.

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Refrigeration Service Operations (Rev 1/99)

NOTE: This orifice may become plugged with dirt unless the refrigeration hos e and solenoid valve are kept clean.

3. Set the thermostat on the lowest setting.

4. Start the truck and run the unit on the engine-driven compressor until the suction pressure stabilizes.

5. Place a jumper wire between CH and the LIS terminal on the liquid injection solenoid.

6. With the jumper wire in place the suction pressure should rise.

7. With the jumper wire removed the suction pressure should return to the stabilized pressure in step 4.

8. If the suction pressure does not change, check the CLU wire for voltage, the liquid injection solenoid valve, or the metering orifice.

9. Shut off the unit and the truck, remove the gauge manifold set and replace the LIS wire.

CHECK VALVE REPAIR (Model 20 Only)

T esting the Check Valve

1. Liquid Injection Metering Orifice

Engine Compressor

Installation

1. Install the metering orifice on the suction hose fitting.

2. Connect the refrigeration hose to the metering orifice fitting.

3. Open the refrigerat ion valves.

Testing the Liquid Injection Solenoid Valve and Metering Orifice

1. Disconnect the LIS wire from the liquid injection solenoid.

2. Install a gauge manifold set on the engine-driven compressor.

The check valve is a very important part of the Model 20 system. The check valve isolates the engine-driven compressor from the electric standby compressor, ensuring the compressor oil and refrigerant do not migrate between compressors. The check valve should be tested when the system is initially charged and operating and anytime the system has been opened for service or repair. Testing the check valve requires two gauge manifold sets.

1. Disconnect the liquid injection solenoid valve wires.

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Refrigeration Service Operations (Rev 1/99)

1. Cap Nut 5. Piston Seat

2. Sealing Washer 6. Washer

3. Spring 7. Screw

4. Piston 8. Valve Body

NOTE: Illustration only, no service parts available.

Check Valve Assembly

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Refrigeration Service Operations (Rev 1/99)

2. With the unit off, install a gauge manifold set on each compressor.

3. Observe the gauge manifold readings of the electric standby compressor. If the high side and low side readings are not the same, open the gauge manifold valves and equalize the pressures. Close the gauge manifold valves.

4. Adjust the thermostat so the unit will ru n in cool. Start the truck and run the unit with the engine-driven compressor.

5. Observe the gauge manifold readings of the enginedriven compressor. The head pressure should increase and the suction pressure should decrease.

6. Observe the gauge manifold readings of the electric standby compressor. The high side pressure should remain the same as the pressure in step 3 after the high and low sides were equalized. If the high side pressure is increasing or has increased noticeably, the discharge check valve is leaking internally.

7. Turn the unit off and shut off the truck engine. Connect the remote control box to an appropriate electric power source.

8. Observe the gauge manifold reading of the enginedriven compressor. If the high side and low side readings are not the same, open the gauge manifold valves and equalize the pressures. Close the gauge manifold valves.

9. Adjust the thermostat so the unit will ru n in cool. Start the unit and run on electric standby.

10. Observe the gauge manifold readings of the electric standby compressor. The head pressure should increase and the suction pressure should decrease.

and low sides were equalized. If the high side pressure is increasing or has increased noticeably, the discharge check valve is leaking internally. Stop the unit.

12. Remove the gauge manifold sets and the electric standby power source. Connect the wires to the liquid injection solenoid valve.

If the check valve is leaking internally, refer to the repair procedures.

Check Valve Repair

Disassembly

1. Remove the refrigerant charge.

2. Loosen the cap nut and remove the cap nut, sealing washer, spring, and piston assem bly.

3. Check the spring. The free length should be 0.57 in. (14.4 mm). Replace the spring if the free length is less than 0.51 in. (13.0 mm).

4. Inspect the pistons and the piston seats. Replace the pistons or the piston seats if they are worn or damaged.

5. Inspect the valve body. The piston bores and the valve body seats should be clean and undamaged. The pistons shoul d move free ly in the pis ton bores. Clean or replace if necessary.

Assembly

NOTE: Coat all parts with compressor oil before assembly.

1. Place the sealing washer on the cap nut.

2. Place the spring on the piston assembly.

3. Place the piston and spring in the cap nut.

11. Observe the gauge manifold readings of the enginedriven compressor. The high side pressure should remain the same as the pressure in step 8 after the high

4. Carefully place the piston and cap nut in the valve body.

5. Tighten the cap nut.

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Refrigeration Service Operations (Rev 1/99)

Check Valve Replacement

Removal

1. Remove the refrigerant charge.

2. Disconnect the refrigeration line connections.

3. Remove the mounting hardware and remove the check valve.

Installation

1. Place the check valve in position and install the mounting hardware.

2. Connect the refrigeration lines.

3. Pressurize the refrigeration system and test for leaks.

4. If no leaks are found, evacuate the system.

5. Recharge the unit with refrigerant and check compressor oil.

EVAPORATOR COIL

Removal

1. Pump down t he low side and equali ze the pressure to slightly positive.

5. Remove the defrost termination switch wire.

6. Unsolder the suction line from the evaporator coil.

7. Remove the mounting bolts and slide the coil from the unit.

Installation

1. Place the coil in the housing.

2. Install the mounting bolts and tighten them.

3. Clean the tubes for soldering.

4. Solder the suction line to the evaporator coil.

5. Connect the hot gas line to the distributor.

6. Connect the expansion valve to the distributor.

7. Connect the defrost termination switch wire.

8. Install the expansion valve on the mounting bracket.

9. Pressurize the system and test for leaks. If no leaks are found, evacuate the system.

10. Connect the evaporator fan motor wires. Install the evaporator panel.

2. Remove the evaporator panel. Disconnect the evaporator fan motor wires.

3. Disconnect the expansion valve from the distributor.

4. Disconnect the hot gas line from the distributor.

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Refrigeration Service Operations (Rev 1/99)

11. Open the refrigeration valves and place the unit in operation. Check the refrigerant charge and the compressor oil and add as required.

3. Disconnect the equalizer line from the expansion valve.

4. Disconnect the liquid line and the distributor from the expansion valve.

5. Remove the expansion valve from the unit.

Installation

1. Install the expansion valve assembly in the unit.

2. Connect the liquid line and the distributor to the expansion valve.

3. Connect the equalizer line to the expansion valve.

4. Clean the suction line to a bright, polished condition. Install the feeler bulb clamps and the feeler bulb on the side of the suction line in its former position. The feeler bulb must make good contact with the suction line or operation will be faulty. Wrap the bulb with insulating tape.

1. Heat Exchanger

2. Suction Pressure Regulator Valve

3. Expansion Valve

4. Evaporator Coil

Evaporator Components

(Thinline Shown Standard Is Similar)

EXPANSION VALVE ASSEMBLY

Removal

1. Pump down t he low side and equali ze the pressure to slightly positive.

2. Remove the feeler bulb from the suction line clamps. Note the position of the feeler bulb on the suction line.

Location of Expansion Valve Bulb

Completely Wrap Bulb with Tape

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Refrigeration Service Operations (Rev 1/99)

5. Pressurize the low side and test for leaks. If no leaks are found, evacuate the low side.

LOW PRESSURE CUTOUT SWITCH

Removal

1. Pump down the low side and stop the unit.

2. Disconnect the wires and remove the switch.

Installation

1. Apply a refrigerant locktite to the threads of the switch.

2. Install and tighten the switch and reconnect the wires.

3. Pressurize the refrigeration system and test for leaks.

4. If no leaks are found, evacuate the low side.

5. Open the receiver tank outlet valve, start the unit and check the refrigerant charge.

SUCTION PRESSURE REGULATOR VALVE

5. Open the refrigeration valves, and place the unit in operation. Check refrigerant charge and add refrigerant as required.

REPLACING REFRIGERANT HOSES

Disassembly

1. Remove the refrigerant charge or pump down the low side.

2. Use two wrenches to loosen the fittings.

3. Remove the hose and remove the fittings from the hose.

Assembly

1. Measure the hose, and using a sharp knife or suitable plastic tube and hose cutter tool, cut to length. Make sure the cut is clean and square. Wipe the inside of the hose clean.

NOTE: DO NOT use a saw to cut the hose.

Removal

1. Pump down t he low side and equali ze the pressure to slightly positive.

2. Release the remaining pressure and unsolder the suction pressure regulator valve from the suction tubes.

Installation

1. Clean the tubes for soldering.

2. Place the valve in position and solder the connections.

3. Pressurize the low side and check for leaks.

4. If no leaks are found, evacuate the low side.

Cut Hose

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Refrigeration Service Operations (Rev 1/99)

2. Place the socket on the hose and turn it counterclockwise until the hose bottoms out. Then back it out 1/4 of a turn.

AGA341

Install Socket

3. Lubricate the nipple threads and the inside of the hose with oil.

4. Screw the nipple into the socket.

AGA383

Flare Fittings

The flare fittings on the liquid injection line sh ould first be tightened finger tight, then they should be turned 3/4 of a turn.

ORS Fittings

Lubricate the ORS fittings with refrigeration oil (same type of oil that is used in the system ) and t ighten them u ntil they bottom out.

Lubricate With Oil

AGA342

ORS Fitting

Page 80

Page 81

V-250 R-404A Conversion Instructions

This option should be only used with units containing a low voltage board. (2C204 47G0 1). S ervice parts # 41-1812 with cycle clutch on high/low pressure cutout operation.

1. Install ne w expansion valve.

2. Install new high pressure cutout switch.

3. Apply R-404A decals over the R-134a decals.

4. Change switches in back of cab control box. Move switches 1 and 2 to the ON position. This will allow the thermostat to be set to -24 F (-31 C).

ON XX OFF

5. Run drain tube heaters into drain hoses until about 6 inches of wire remains out. Keep wires to top side of drain hoses and slip hoses over the drain tubes coming out of the evaporator.

1. Drain Hose

2. Drain Pan

3. Heater

6. Unplug the defrost solenoid from the low voltage control. Plug drain tube heater harness into control box plug and defrost solenoid into heater harness. Run heater harness to evapor ator and plug drain tube heaters into harness.

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Page 83

Structural Maintenance

UNIT INSPECTION

Inspect the unit during the pre-trip inspection and during scheduled maintenance inspections for loose or broken wires or hardware, compressor oil leaks, or other physical damage which might affect the unit performance and require the repair or replacement of parts.

EVAPORATOR COIL

Clean the evaporator coil during scheduled maintenance inspection by blowing compressed air down through the coil out into the box (direction opposite the normal air flow). Inspect the coil and fins for damage and repair if necessary (requires removing the evaporator fan and front cover).

Roofmount Unit

CAUTION: Air pressure should not be high enough to damage the coil fins.

CONDENSER COIL

Clean the condenser coil during scheduled maintenance inspections by blowing compressed air from the back side of the coil out toward the front of the unit (the direction opposite normal air flow). Inspect the coil and fins for damage and repair if necessary.

CONDENSER FAN LOCATION

Mount the condenser fan so the hub is flush with the end of the shaft.

UNIT MOUNTING BOLTS

Periodically check and torque the unit mounting bolts to 60 ft-lb (81 N•m).

Nosemount Unit

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Compressor and Clutch Maintenance

Operation

A stationary field coil is mounted on the compressor body concentric with the shaft. A pulley as sembly, consisting of a pulley, a disc and a hub is mounted on the shaft of the compressor. The hub and disc are flexibly connected with flat springs that in the disengaged position, hold the disc slightly away from the pulley web (friction surface).

When an electric current flows through the field coil, a m agnetic field is created. The magnetic field pulls the disk against the pulley web and compresses the flat springs. This causes the hub and disk to rotate with the pulley.

Removal

1. Remove the center bolt using the puller arbor (TK 204-804) to prevent drive plate rotation.

1. Holder

Remove Center Bolt

1. Hub 4. Disk

2. Stationary Field Coil 5. Flat Springs

3. Pulley

Compressor Clutch Assembly

CLUTCH REMOVAL

NOTE: Make sure the proper tools are available before performing maintenance procedures. Refer to the tool listing at the end of this chapter for tools required. Contact your local Thermo King dealer for further information.

2. Remove the drive plate using the shaft seal kit (TK 204-805). Then remove the shims from either the drive shaft or the drive plate.

Remove Drive Plate

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Compressor and Clutch Maintenance (Rev 1/99)

3. Remove the snap ring using external snap ring pliers (TK 204-808).

4. Remove the cover.

1. Snap Ring

2. Cover

NOTE: To avoid damaging the pulley groove, the pulley claws should be hooked into (NOT UNDER) the pulley groove.

Remove Pulley

Remove Snap Ring and Cover

5. Remove the pulley assembly using the clutch remover (TK No. 204-806) and the spacer positioned on the cylinder head hub.

6. Remove the coil’s lead wire from the holder on the top of the compressor.

7. Remove the three screws that attach the coil to the compressor and remove the coil.

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Compressor and Clutch Maintenance (Rev 1/99)

NOTE: DO NOT hold the coil by the lead wire.

Remove Coil

Inspection

1. Drive Plate

If the contact surface is scorched, the drive plate and pulley should be replaced.

2. Pulley Assembly

Inspect the appearance of the pulley assembly. If the pulley’s contact surface is excessively grooved due to slippage, both the pulley and drive plate must be replaced. There should also be no foreign matter, such as oil or grit, lodged between the clutch plate and pulley. Thoroughly clean these contact surfaces and the drive plate.

3. Coil

Inspect the coil for a loose connector or cracked insulation. If the insulation is cracked, replace the coil. Repair or replace the wire or the connector if either is loose or dam aged.

1. Drive Plate

2. Pulley Assembly

3. Coil

Inspect Components

Clutch Installation

NOTE: Before installation refer to the “Inspection” procedures previously described.

1. Confirm that the felt is installed on the front of the cylinder head.

2. Install the coil on the compressor (with the lead wire on top). At this time, confirm that the coil’s concave portion is aligned with the felt and then tight en the mounting screws to the specified torque.

NOTE: Specified torque: 2.9 to 4.3 ft-lbs (0.4 to 0.6 kgm).

3. Install the lead wire in the wire holder on the compressor.

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Compressor and Clutch Maintenance (Rev 1/99)

5. Install the cover and the snap ring using external ring pliers.

NOTE: When installing the snap ring, the chamferred inner edge of the snap ring should face upward.

1. Felt

Install Coil

4. Install the pulley assembly using the compressor holder (TK No. 204-807) and a hand press.

Install Pulley

1. Snap Ring

2. Cover

Install Cover and Snap Ring

6. Install the driver plate on the drive shaft, together with the original shim(s). Press the drive plate down by hand.

7. Tighten the bolt to the specified torque using the puller arbor (TK No. 204-804) to prevent drive-plate rotation.

NOTE: Specified torque: 8.7 to 10.1 ft-lbs (1.2 to

1.4 kgm).

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Compressor and Clutch Maintenance (Rev 1/99)

After tightening the bolt, ensure that the pu lley rotates smoothly.

1. Shims

Install Shims and Drive Plate

8. Ensure that the clutch clearance is as specified. If necessary, adjust the clearance using shims.

Adjusting shims are available in the following thicknesses:

Shim TK P/N Thickness in. (mm)

TK 11-8031 0.0039 in. (0.1 mm) TK 11-8032 0.0118 in. (0.3 mm) TK 11-8033 0.0197 in. (0.5 mm)

NOTE: Specified clearance: 0.01 to 0.02 in. (0.3 to

0.6 mm).

Check Clearance

Electrical Connection

1. Connect the lead wire to the electrical circuit.

NOTE: The stationary field is grounded at the factory; therefore, it is necessary only to connect the hot (lead) wire.

2. Engage and disengage the clutch several times to check the clutch engagement. The disc should snap firmly against the pulley.

SHAFT SEAL COVER AND SHAFT SEAL: REMOVAL AND INSTALLATION

Removal

1. Remove the magnetic clutch assembly, as outlined in “Magnetic Clutch Removal” section of this manual.

2. Remove the felt pad.

3. Use the seal remover (from the shaft seal kit P/N 204-

805) to remove the shaft seal cover. Turn the seal remover to engage the hook on the seal remover with

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Compressor and Clutch Maintenance (Rev 1/99)

the hook on the shaft seal cover, then slowly pull the shaft seal cover out of the cylinder head.

NOTE: The shaft seal cover SHOULD NOT be reused. Always use a new shaft seal cover when reassembling a compre ssor.

1. Shaft Seal Cover

2. Felt Pad

Remove Shaft Seal Cover

4. Use the seal remover (from the shaft seal kit P/N 204-

805) to remove the shaft seal. Turn the seal remover to engage the hook on the seal remover with the hook on the shaft seal, then slowly pull the shaft seal out of the cylinder head.

1. Shaft Seal

Remove Shaft Seal

Inspection

The shaft seal should not be reused. Always use a new shaft seal when reassembling a compressor. Be extremely careful to make sure the lip of the shaft seal that is being installed is not scratched or damaged in any way. Make sure the shaft seal is free from lint and dirt that could damage the shaft seal surface.

Inspect S haft Seal

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Compressor and Clutch Maintenance (Rev 1/99)

Shaft Seal Installation

Before installing a shaft seal inspect it carefully (see Inspection).

1. Clean the section of the front cylinder head that holds shaft seal.

2. Apply clean compressor oil to the new shaft seal and to the front cylinder head. If the slip surfaces are dirty, clean them with thinners, dry the clean surfaces and apply clean compressor oil.

3. Place the seal guide (from the shaft seal kit P/N 204-805) on the end of the shaft.

4. Place the shaft seal on the seal guide and slide the seal into the cylinder head.

1. Seal Guide

2. Shaft Seal

Place Shaft Seal on Guide

5. Use the seal installer (from the shaft seal kit P/N 204-805) to press the shaft seal into the cylinder head as far as possible.

1. Seal Guide

Place Guide on Shaft

6. Remove the seal guide from the shaft.

Press Seal Into Cylinder Head

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Compressor and Clutch Maintenance (Rev 1/99)

7. Place the seal guide (from the shaft seal kit P/N 204-805) on the end of the shaft.

8. Place the shaft seal cover on the seal guide and slide the shaft seal cover into the cylinder head.

Install Shaft Seal Cover

9. Use the seal installer (from the shaft seal kit P/N 204-805) to press the shaft seal cover into the cylinder.

Special Tools

8932a

Clutch Remover P/N 204-806

10. Remove the seal guide from the shaft.

NOTE: Position the shaft seal cover as shown in the illu stration. The felt pad should also be replaced with a new one when the shaft seal is replaced.

Proper Shaft Seal Cover Position

8932b

Compressor Holder P/N 204-807

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Compressor and Clutch Maintenance (Rev 1/99)

Clutch Installation Kit P/N 204-890

Snap Ring Pliers P/N 204-808

8932c

8932e

Shaft Seal Kit P/N 204-805

8932d

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Compressor and Clutch Maintenance (Rev 1/99)

8932f

Each compressor comes with a standard charge of Polyol Ester (POE) oil inside. This quantity of oil is enough to supply the compressor lubrication wh en it is installed into an already “oil wet” system. New systems require an extra quantity of oil be added to “wet” all the interior surfaces of the system.

During normal operation there is always a quantity of oil that travels around inside the system. This oil lubricates all the components, returns to the compressor for a while, and again travels around the system.

Adding Extra Oil to the System

The initial oil charge into a new system is based on the size of the system and the amount of oil, which remains in the compressor during operation.

Pulley Arbor P/N 204-804

SYSTEM COMPRESSOR AND OIL

Installation of the Compressor

The compressor is mounted in the condenser section. The side to side mounting angle of the compressor must remain ± 45 from the horizontal. The forward to backward angle must be within ± 10 of horizontal. Access to the air conditioning system service ports is from the top of the unit.

The correct oil to use in the V250 using R-134a and R404A is Polyol Ester (POE) oil (TK No. 203-413). Any extra or replacement oil should be placed into the system at the receiver tank port.

CAUTION: Keep all oil containers tightly sealed

from the air. Oil tends to absorbed moisture from the air and can become contaminated if left open. If contaminated oil is put into a system, it may damage t he components of the system.

Major Loss of Refrigerant

In case of a major loss of refrigerant, it must be assumed that some system oil is lost also. The oil level should be verified by the “Checking the Oil Level” method in this manual.

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Compressor and Clutch Maintenance (Rev 1/99)

Checking the Oil Level

Drain the Oil

Draining the Oil

Remove the compressor from the unit and dr ain the oil fr om the compressor drain plug and all other ports. Turn the clutch (rotating the internal compressor parts) by hand and drain oil again. Repeat until all oil is removed from the compressor. Measure the oil in liquid ounces. Also, inspect the oil for signs of contamination.

Oil contamination.

1. Dirt in the oil.

2. Color changed to a varnish color.

3. Presence of foreign substances, metal shavings, etc. in the oil.

NOTE: Always replace oil with new fresh oil taken from a sealed container only.

NOTE: Always replace the system filter-dri er anytime the system has been opened for service.

When a System Becomes Contaminated

A severely contaminated system may be indicated by black oil in the compressor. If severe contamination occurs, it will be necessary to flush the complete system. If flushing is required, use industry approved materials.

In all cases when this occurs you must determine the extent of contamination. Do this by removing the filter-drier and determine if the darker colored oil is present at that point of the system too. If it is, flushing the system is recommended.

If the oil appears clean at the filter-drier, install a new filterdrier and replace the compressor with clean new oil. Refer to checking and draining the compressor oil section for details.

CAUTION: Any extra or replacement oil should be placed into the system at the receiver tank port.

Electrical Connection

1. Connect the lead wire to the electrical circuit.

NOTE: The stationary field is grounded at the factory; therefore, it is necessary only to connect the hot (lead) wire.

2. Engage and disengage the clutch several times to check the clutch engagement. The disc should snap firmly against the pulley.

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Compressor and Clutch Maintenance (Rev 1/99)

Clutch T est

1. If the field coil lead wire is broken, replace the field coil.

2. Check the amperage and voltage. The amperage range should be 3 .6 to 4.2 amps at 12 volts or 1.8 t o 2.1 amps at 24 volts. Note the following symptoms and conditions.

a. A very high amperage reading—a short within the

field coil.

b. No amperage reading—an open circuit in the

winding.

c. An intermittent or poor system ground results in

lower voltage at the clutch. Check for tigh t fit of the coil retaining snap ring or coil retaining screws for good ground.

d. Replace field coil if it has an open or short circuit.

3. Air Gap—An incorrect air gap could cause erratic engagement or disengagement and/or clutch rattle. Check the air gap with a feeler gauge (0.01 to 0.02 in. [0.3 to 0.6 mm]). Adjust per the Clutch Installation chapter.

BELT TENSIONS

Engine/Compressor Belt and Pulleys

Correct pulley alignment and proper belt tension are very important factors in compressor installation. The compressor clutch must be perfectly aligned with the engine pulley and any auxiliary idler or belt adjustment pulley components. When installing the clutch, be sure the shaft drive key is in place and the shaft bolt is properly tightened. Check the pulley alignment by holding a 24 to 35 i n. (60 to 90 cm) long rod, 0.5 in. (13 mm) in diameter firmly into the V-groove of the clutch pulley and make sure the rod aligns squarely with the engine drive pulley gr oove. Double check by making sure the belt goes from pulley to pulley in perfect alignment with no indication of a sideward bend.

Adjust the belt tension to 58 to 60 on TK Gauge P/N 204-

427. Check the belt tension again after 36 to 48 hours of initial operation of the unit because the belt may stretch slightly during the first hours of use. Remember, good alignment and proper belt tension ensure long belt life.

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Electric Motor/Compressor Belt

Loosen the bolts that fasten the compressor mounting bracket to the frame and turn the adjusting nut to tension the belt. Tighten the bolts that fasten the compressor mounting bracket to the frame when the belt tension reads 58 to 60 to TK Gauge P/N 204-427.

NOTE: Do not overtighten the belts. Proper bel t tension should allow the belt to be deflected 0.5 in. (13 mm) at the center of the span with no motor m ovement. A belt tha t is too tight causes severe overload on the compressor and motor bearings. Use only approved Thermo King Service Parts replacement belts. They are specially designed for these units.

Compressor and Clutch Maintenance (Rev 1/99)

1. Compressor Mounting Bracket Bolt

2. Adjuster

Electric Motor/Compressor Belt

Page 98

Page 99

Over-the-Road Mechanical Diagnosis

If the desired box temperature cannot be obtained, any of the following may be indicated:

1. EXCESSIVE HEAT LOAD. An excessive heat load on the system will be caused by too many, or excessively long, stops with the doors open. Excessive heat loads will also be caused by loose doors, loose body panels, warm loads and poor insulation.

2. DIRT ON COILS. Dirt on the condenser or evaporator coils acts as an insulator reducing the capacity of the unit.

3. INCORRECT BELT TENSION. If the drive belt is not correctly tensioned, the compressor will not be driven at the proper speed, and unit efficiency will be reduced. By contrast, too much tension will place an additional load on the bearings causing rapid wear.

4. SHORTAGE OF REFRIGERANT. Shortage of refrigerant reduces the capacity of the unit. Find and remedy the cause of the shortage and recharge the system. DO NOT operate the unit if there is an indication of low charge. DO NOT operate below 30 F (-1 C) box temperature if the refrigerant leve l is below the sight glass on the receiver tank.

5. FAULTY EXPANSION VALVE ADJUSTMENT. High superheat settings will starve the evaporator causing low suction pressure. Low superheat setti ngs w ill flood the coil causing high suction pressure. The superheat setting should be adjusted ONLY by a trained refrigeration service technician.

The superheat setting is 8 F (4.4 C) at 0 F (-18 C) box temperature.

6. EXCESSIVE OIL. Too much compressor oil in the system may result in lower th an normal suction pressure as well as lowered capacity.

7. MOISTURE IN THE SYSTEM. Symptom: Expansion valve freeze-up—will not refrigerate. Usually this can be checked by warming the expansion valve with either

a hand or hot towels to see if the valve opens. Evacuate the system in the same manner used during installation. Install a new drier.

8. EXPANSION VALVE LOSES ITS CHARGE. If the expansion valve loses its charge, the valve will close causing the system to go into vacuum. Replace the valve.

9. AIR IN THE SYSTEM. Air is not condensable. Its presence in the system increases head pressure. When the compressor is stopped, air will gather at the high point of the high side. Evacuate the system.

10. TEMPERATURE OF THE LIQUID LINE. During normal operation, the liquid line will be slightly warmer than the surrounding air. An extremely hot line indicates either a shortage of refrigerant or a lack of a liquid seal at the receiver outlet. A cold line indicates a restriction, and some flashing takes place in the liquid line sight glass.

11. DIRTY OR WET DRIER. If the outlet line of the drier is colder than the inlet line, the drier is either saturated with moisture or is dirty and must be replaced.

12. DIRT IN THE EXPANSION VALVE SCREEN. Recover the refrigerant charge, remove the screen and clean. If the moisture is in the refrigeration system, it will collect at the expansion valve and freeze. This is indicated by abnormally low suction pressure. Clean the system, replace the drier, evacuate the system pressurize and check for leaks. If no leaks are found, charge the system.

13. ICE ON THE EVAPORATOR COIL. Run the unit through a defrost cycle to remove the ice.

14. AIR FLOW . Do not load product directly in front of the air return or discharge. Ensure that the fan is correctly positioned in the orifice to achieve maximum air flow.

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Over-the-Road Mechanical Diagnosis (Rev 1/99)

15. COMPRESSOR LIFE. The following will shorten the life of a compressor:

• Operating a contaminated system

• No oil trap

• Insufficient oil charge

• Wrong oil or mixed oil

• Lack of compressor lubrication on installation-startup

• Excess compressor speed (refer to the chart below)

• Clogged oil separator (JetLube™)

• Clogged liquid injection orifice (JetCool™)

• Defective temperature switch (JetCool™)

Road Compressors

Specifications Relative Performance

Model Displ. Dimensions

MAX RPM (Metrics) A B C* D

TM 16HD 3000 rpm

TM 15 HD

4000 rpm

TM 13 HD

6000 rpm

TM 13 HD

6000 rpm

TM 08 HD

6000 rpm

10.5 cid

(163 cc)

9.0 cid

(147 cc)

8.0 cid

(131 cc)

8.0 cid

(131 cc)

5.0 cid (82 cc)

3.28in.

(83.3 mm)

3.28 in.

(83.3 mm)

3.28 in.

(83.3 mm)

2.89 in.

(73.3 mm)

2.03 in.

(515 mm)

4.41 in.

(112 mm)

4.41 in.

(112 mm)

4.41 in.

(112 mm)

3.86 in.

(98 mm)

3.15 in.

(80 mm)

8.77 in.

(222.8 mm)

8.55 in.

(217.3 mm)

8.55 in.

(217.3 mm)

8.23 in.

(209 mm)

6.85 in.

(174 mm)

4.09 in.

(104 mm)

4.09 in.

(104 mm)

4.09 in.

(104 mm)

4.09 in.

(104 mm)

4.41 in.

(112 mm)

Drive

Pulley

Dia.

Compressor RPM Formula

Clutch

Pulley

Dia.

6.5 ÷ 5.25 X 2500 = 3095

High

Engine

RPM

Maximum

Compressor

RPM

*Add 1 in. (2.5 cm) to dimensions

for bolt-on manifold. Bolt-on manifold for TM 16 HD, TM 15 HD, and TM 13 HD only.