MCC 50-2104, T50-2112 Service Manual

T-367 Manual

OPERATION/SERVICE MANUAL

for

MCC Eco Xcel SERIES

T-367

REV. 05/2015

TABLE OF CONTENTS

SAFETY SUMMARY Safety--1.......................................................................

DESCRIPTION 1--1...............................................................................

1.1 INTRODUCTION 1--1.....................................................................

1.2 GENERAL DESCRIPTION 1--2.............................................................

1.2.1 Rooftop Unit 1--2......................................................................

1.2.2 Condensing Section 1--2...............................................................

1.2.3 Evaporator Sections 1--3...............................................................

1.2.4 MCC Microprocessor 1--3..............................................................

1.3 REFRIGERATION SYST EM COMPONENT SPECIFICATIONS 1-- 3.............................

1.4 ELECTRICAL SPECIFICATIONS -- MOTORS 1-- 3............................................

1.5 SAFETY DEVICES 1--4...................................................................

1.6 AIR CONDITIONING REFRIGERATION CYCLE 1--5..........................................

1.7 HEATING CYCLE 1--5....................................................................

OPERATION of MCC XCEL DRIVER DISPLAY 2--1...................................................

2.1 General Description 2--1...................................................................

2.2 STARTING, STOPPING AND OPERATING INSTRUCTIONS 2--1..............................

2.2.1 Starting 2--1..........................................................................

2.3 SEQUENCE OF OPERATION 2-- 2..........................................................

2.3.1 Function of Keys when “Engine On” and controller active: 2--2...............................

2.4 BASIC OPERATING INSTRUCTIONS 2--3..................................................

2.4.1 Display 2--3..........................................................................

2.4.2 Interior Set Point Temperature Control 2--3...............................................

2.4.3 Blower Speed Setting 2--3..............................................................

2.4.4 Mode Selection Descriptions 2--3........................................................

2.4.5 Capacity Control “Ladder” Diagrams 2--3.................................................

2.4.6 Display Settings 2--5...................................................................

2.4.7 HVAC Information Screens 2--6.........................................................

2.4.8 HVAC Diagnostics Screens 2--7.........................................................

2.4.9 HVAC Alarm Description 2--8...........................................................

2.5 MCC Eco NG Coolview 2-- 9...............................................................

2.5.1 Starting the MCC Coolview Application 2--10...............................................

2.5.2 Coolview Screen Layout 2--11...........................................................

2.5.3 Eco NG Display Pin out Description 2--16..................................................

2.5.4 Eco NG Controller Pin out Description 2--17...............................................

TROUBLESHOOTING 3--1.........................................................................

3.1 System Will Not Cool 3--1..............................................................

3.2 System Runs But Has Insufficient Cooling 3--1............................................

3.3 Abnormal Pressures 3--1...............................................................

3.4 Abnormal Noise Or Vibrations 3--1.......................................................

3.5 No Evaporator Air Flow Or Restricted Air Flow 3--2........................................

3.6 Expansion Valve Malfunction 3--2........................................................

3.7 Heating Malfunction 3--2...............................................................

SERVICE 4-1....................................................................................

4.1 MAINTENANCE SCHEDULE 4-1...........................................................

T-367Rev . 05/2015

4.2 OPENING TOP COVER (EVAPORATORS) 4-2..............................................

4.3 REMOVING TOP COVERS (CONDENSER) 4-2.............................................

4.4 SUCTION AND DISCHARGE SERVICE VALVES 4-3.........................................

4.4.1 Installing R--134a Manifold Guage Set 4-4...............................................

4.4.2 SYSTEM PUMP DOWN FOR LOW SIDE REPAIR 4-6....................................

4.4.3. Removing Entire System Charge 4-7....................................................

4.5 REFRIGERANT LEAK CHECK 4-7.........................................................

4.6 EVACUATION AND DEHYDRATION 4-7....................................................

4.6.1 General 4-7..........................................................................

4.6.2 Preparation 4-7.......................................................................

4.6.3 Procedure for Evacuation and Dehydrating System (One Time Evacuation) 4-8...............

4.6.4 Procedure for Evacuation and Dehydrating System (Triple Evacuation) 4-8...................

4.7 CHECKING AND ADDING REFRIGERANT TO SYSTEM 4-8..................................

4.7.1 Checking Refrigerant Charge By Pressures 4-8...........................................

4.7.2 Checking Refrigerant Charge By Receiver Sight Glasses 4-9...............................

4.7.3 Adding Full Charge 4-9................................................................

4.7.4 Adding Partial Charge 4-11.............................................................

4.8 CHECKING SYSTEM FOR NON--CONDENSIBLES 4-11.......................................

4.9 CHECKING AND REPLACING HIGH OR LOW PRESSURE SWITCH 4-11.......................

4.10 FILTER--DRIER 4-12......................................................................

4.10.1 To Check Filter--Drier 4-12...............................................................

4.10.2 T o Replace Filter--Drier 4-12.............................................................

4.11 SERVICING THE LIQUID LINE SERVICE VALVE 4-12.........................................

4.11.1 Coil Replacement 4-13.................................................................

4.11.2 Internal Part Replacement 4-13..........................................................

4.11.3 Replace Entire LLS Valve 4-13...........................................................

4.12 THERMOSTATIC EXPANSION VALVE 4-14..................................................

4.12.1 Valve Replacement 4-14................................................................

4.12.2 Superheat Measurement 4-14...........................................................

4.13 REPLACING EVAPORATOR RETURN AIR FILTERS 4-15.....................................

4.14 COMPRESSOR MAINTENANCE 4-16.......................................................

4.14.1 Shaft Seal Reservoir 4-16...............................................................

4.14.2 Refrigerant Removal From An Inoperative Compressor. 4-16................................

4.14.3 Pump Down An Operable Compressor For Repair 4-16.....................................

4.14.4 Removing the Compressor 4-17.........................................................

4.14.5 Transferring Compressor Clutch 4-18.....................................................

4.14.6 Compressor Oil Level 4-19..............................................................

4.14.7 Checking Unloader Operation 4-19.......................................................

4.15 TEMPERATURE SENSOR CHECKOUT 4-21.................................................

4.16 PRESSURE TRANSDUCER CHECKOUT 4-21...............................................

4.17 REPLACING SENSORS AND TRANSDUCERS 4-21..........................................

ELECTRICAL 5--1................................................................................

5.1 INTRODUCTION 5--1.....................................................................

T-367Rev . 05/2015

LIST OF TABLES

Table 1-- 1 Models 1--1.............................................................................

Table 1-- 2 Additional Support Manuals 1--1............................................................

Table 3-- 1 General System Troubleshooting Procedures 3--1............................................

Table 4-1 Temperature Sensor Resistance 4-21........................................................

Table 4-2 Pressure Transducer Voltage 4-22...........................................................

Table 4-3 R--134a Temperature -- Pressure Chart 4-23..................................................

LIST OF FIGURES

Figure1--1RooftopUnit(EcoXcel) 1--2.............................................................

Figure 1--2 Refrigerant Flow Diagram 1--6...........................................................

Figure 1--3 Heat Flow Diagram 1--7.................................................................

Figure 2-1 Driver Display Module-- Control Layout 2--1................................................

Figure 2-2 Driver Display Module-- Display Layout 2--2................................................

Figure 2-3 Capacity Control Ladder Diagrams 2--4....................................................

Figure 2-4 HVAC DISPLAY SETTINGS 2--5..........................................................

Figure 2-5 HVAC INFORMATION SCREENS 2--6....................................................

Figure 2-6 HVAC DIAGNOSTIC SCREENS 2--7......................................................

Figure 2-7 MCC Eco NG Display Alarms 2--8........................................................

Figure 2-8 MCC Eco NG Coolview (Example Screenshot) 2--9.........................................

Figure 2-9 MCC Eco NG Coolview (VIEW Tab) 2--10...................................................

Figure 2-10 MCC Eco NG Coolview Inputs and Mode (VIEW Tab) 2--11..................................

Figure 2-11 MCC Eco NG Coolview Outputs (VIEW Tab) 2--12..........................................

Figure 2-12 MCC Eco NG Coolview Error List (ERROR Tab) 2--12.......................................

Figure 2-13 MCC Eco NG Coolview Statistics (HOURS Tab) 2-- 13.......................................

Figure 2-14 MCC Eco NG Coolview Simulation Mode 2--14.............................................

Figure 2-15 MCC Eco NG Coolview Data Logger 2--15.................................................

Figure 2-16 MCC Eco NG Display Pinout 2--16........................................................

Figure 2-17 MCC Eco NG ControllerPinout 2--17......................................................

Figure 4-1 Opening Top Cover (Evaporator) 4-2......................................................

Figure 4-2 Removing Top Covers (Condenser) 4-2...................................................

Figure 4-3 Suction or Discharge Service Valve 4-3...................................................

Figure 4-4 Manifold Gauge Set (R--134a) 4-4........................................................

Figure 4-5 Service Connections 4-5................................................................

Figure 4-6 Rule of Thumb 4-8.....................................................................

Figure 4-7 Service Connections 4-10................................................................

Figure 4-8 Checking High Pressure Switch 4-11.......................................................

Figure 4-9 Filter--Drier Removal 4-12................................................................

Figure 4-10 Liquid Line Solenoid Valve 4-13..........................................................

Figure 4-11 Thermostatic Expansion Valve Bulb and Thermocouple 4-14.................................

Figure 4-12. Compressor Service Connections 4-16...................................................

Figure 4-13. Compressor Service Connections 4-16...................................................

Figure 4-14. Compressors 4-17.....................................................................

T-367Rev . 05/2015

LIST OF FIGURES (Continued)

Figure 4-15. Removing Bypass Piston Plug 4-17......................................................

Figure 4-16. Compressor Clutch 4-18................................................................

Figure 4-17 Transducer Terminal Location 4-21.......................................................

Figure 5--1 Schematic 50--2104S 5--2...............................................................

Figure 5--2 Schematic T50--21 12S 5--3..............................................................

T-367Rev . 05/2015

SAFETY SUMMARY

GENERAL SAFETY NOTICES

The following generalsafety notices supplement the specific warnings and cautions appearing elsewhere in this manual. They are recommended precautions that must be understood and applied during operation and maintenanceof the equipment covered herein. A listingof the specificwarningsand cautions appearing elsewhere in the manual follows the general safety notices.

FIRST AID

An injury, no matter how slight, should never go unattended. Always obtain first aid or medical attention immediately.

OPERATING PRECAUTIONS

Always wear safety glasses.

Keep hands, clothing and tools clear of the evaporator and condenser fans.

No work should be performed on the unit until all start-stop switches are placed in the OFF position, and power supply is disconnected.

Always work in pairs. Never work on the equipment alone.

In case of severe vibration or unusual noise, stop the unit and investigate.

MAINTENANCE PRECAUTIONS

Beware of unannounced starting of the evaporator and condenser fans. Do not open the unit cover before turning power off.

Be sure power is turned off before working on motors, controllers, solenoid valves and electrical controls. Tag circuit breaker and power supply to prevent accidental energizing of circuit.

Do not bypass any electrical safety devices, e.g. bridging an overload, or using any sort of jumper wires. Problems with the system should be diagnosed, and any necessary repairs performed by qualified service personnel.

When performing any arc welding on the unit, disconnect all wire harness connectors from the modules in the control box. Do not remove wire harness from the modules unless you are grounded to the unit frame with a static-safe wrist strap.

In case of electrical fire, open circuit switch and extinguish with CO2(never use water).

Safety--1

T-367 Rev. 05/2015

SPECIFIC WARNINGS AND CAUTIONS

WARNING

Use of an electro-magnetic valve as a means of positive shutoff for service is not recom

mended for safety, or good service practice.

WARNING

Be sure to observe warnings listed in the safety summary in the front of this manual be

fore performing maintenance on the hvac system

WARNING

Read the entire procedure before beginning work. Park the vehicle on a level surface,

with parking brake applied. Turn main electrical disconnect switch to the off position.

WARNING

Do Not Use A Nitrogen Cylinder Without A Pressure Regulator

WARNING

Do Not Use Oxygen In Or Near A Refrigeration System As An Explosion May Occur.

WARNING

The Filter-drier May Contain Liquid Refrigerant. Slowly Loosen The Connecting Nuts And Avoid Con

tact With Exposed Skin Or Eyes.

CAUTION

The 50-2104 Rooftop Systems have R134a service port couplings installed on the compressor and on the unit piping.

CAUTION

To prevent trapping liquid refrigerant in the manifold gauge set be sure set is brought to suction pres

sure before disconnecting.

Safety--2

T-367 Rev. 05/2015

SECTION 1

DESCRIPTION

1.1 INTRODUCTION

This manual contains Operating Instructions, Service Instructions and Electrical Data for the EcoXcel Model Air Conditioning and Heating equipment furnished by Mobile Climate Control as showninTable1-1.

The system is identified with a Model/Serial number tag located inside the evaporator section, on the rear bulkhead wall of the assembly. Example is shown in Figure 1-1.

Models consists of a Rooftop unit containing the condensing section, the evaporator sections and

Table 1-1 Models

Model

50-2104 24 VDC

T50-2112 24 VDC

Voltage Controller With Heat Single Loop W/Covers

MCC EcoTemp NG

Microprocessor

MCC EcoTemp NG

Microprocessor

engine compartment mounted compressor. To complete the system, the air conditioning and heating equipment interfaces, electrical cabling, refrigerant piping, engine coolant piping (for heating), duct work and other components furnishedby Mobile Climate Control and/or the bus manufacturer.

Additional support manuals are shown in Table 1-2.

Operation of the unit is controlled automatically by a Mobile Climate Control Microprocessor based controller. The controls maintain the vehicle's interior temperature at the desired set point.

Yes X X

Table 1-2 Additional Support Manuals

MANUAL NUMBER

T-367PL Eco Xcel Models Service Replacement Parts List

EQUIPMENT COVERED TYPE OF MANUAL

1--1

T-367Rev. 05/2015

1.2 GENERAL DESCRIPTION

1.2.1 Rooftop Unit

The rooftop unit includes the condenser section and the evaporator sections (See Figure 1-1).

Condenser Section

Evaporator Section

Figure 1-1 Rooftop Unit (Eco Xcel)

1.2.2 Condensing Section

The condensing section includes 2 micro-channel condenser coils, four (4) fan and motor assemblies and receiver tank assembly with sight glasses, moisture indicator and fusible plug

The condenser coils provideheat transfer surface for condensing refrigerant gas at a high temperature and pressure into a liquid at high temperature and pressure. The condenser fans circulate ambient air across the outside of the condenser tubes at a temperature lower than refrigerant circulating inside the tubes; this results in condensation of the refrigerant into a liquid. The receiver tank is also

EVAPORATOR SECTION

Interior Location

Model/Serial Number Plate

equipped with a pressure relief valve (fusible plug) which protects the system from unsafe high pressure conditions. The filter-drier,located in the evaporator section,removes moisture and debris from the liquid refrigerant before it enters the thermostatic expansion valve in the evaporator assembly.

a. Condenser fan operation

Low Speed ON: 150 psig (10.31 bar) Low Speed OFF: 120 psig (8.27 bar)

High Speed ON: 225 psig (15.51 bar) High Speed OFF: 165 psig (11.38 bar)

1--2

1.2.3 Evaporator Sections

The evaporator section includes the evaporator coil, two (2) blower motor assemblies, thermostatic expansion valve, heater coil assembly, heater valve, filter/drier, service valves and condensate drain connections.

The evaporator coil provides heat transfer surface for transferring heat from air circulating over the outside of the coil to refrigerant circulating inside the tubes; thus providing cooling. The heating coils provide a heat transfer surface for transferring heat from engine coolant water circulating inside the tubes to air circulatingover the outside surface of the tubes, thus providing heating. The fans circulate the air over the coils. The air filters (OEM supplied) remove dirt particles from the air before it passes over the coils. The thermostatic expansion valve meters the flow o f refrigerant entering the evaporator coils. The heat valve controls the flow of engine coolant t o the heating coils upon receipt of a signal from the controller. The condensate drain connections provide a means for connecting tubing for disposing of con densate collected on the evaporator coils during cooling operation.

1.2.4 MCC Microprocessor

The MCC controller maintains desired temperature set point by controlling compressor capacity, fan speeds and heat valve operation. Refer to Section 2, for operational sequences.

1.3 REFRIGERATION SYSTEM COMPONENT SPECIFICATIONS

a.System Capacity: Cooling - 120,000 Btu/Hr (35 kW)

Heating - 126,000 Btu/Hr (37 kW)

b. Refrigerant Charge R-134a (Approximate)

NOTE

Refrigerant charge will depend on hose lengths and diameters; or if there is an InDash unit (front evaporator). The following should only be used as a guideline.

c. Compressor

Compressor

No. Of Cylinders 6

Weight, (Dry) With Clutch 145 Lbs. (66 kg)

Oil Charge

d. Thermostatic Expansion Valve:

7 Ton Capacity- Adjustable

e. High Pressure Switch (HPS)

Opens at: 360 ±10 psig (24.82 ±0.68bar) Closes at: 285 ±15 psig (19.65 ±0.68bar)

f. Low Pressure Switch (LPS)

Opens at: 6 ±3psig (0.41 ±0.20 bar) Closes at: 25 ±3psig(1.7±0.20 bar)

g. Water Temperature Switch (WTS) (If Equipped)

[Bus Manufacturer Supplied - Suggested close on tempera ture rise at 105°F(41°C)]

Normally Closed

Normally Open

05G

5.5 pints

(2.6 liters)

1.4 ELECTRICAL SPECIFICATIONS - MOTORS

a. Evaporator Blower/Motor

Evaporator Motor

Full Load Amps (FLA) ~25

Bearing L ubrication

b. Condenser Fan Motor

Condenser Motor

Full Load Amps (FLA) ~7

Bearing L ubrication

c. Temperature Sensors (All)

Input Range: -40 to 167° F(-40to75°C) Output: NTC 10K ohms at 77° F(25°C)

d. Ambient Sensor (Controls Compressor Outputs)

Brushless

24 VDC

Factory Lubricated

(additional grease not required)

Brushless

24 VDC

Factory Lubricated

(additional grease not required)

50-2104 with 05G Compressor

13 ± 0.5 Pounds (5.9 ± 0.23 kg)

1--3

Opens at: 43° F(6.1°C) Closes at: 47° F(8.3°C)

T-367Rev. 05/2015

1.5 SAFETY DEVICES

System components are protected from damage caused by unsafe operating conditions with safety devices. Safety devices with Mo b ile Climate Contro l supplied equipment include high pressure switch (HPS), low pressure switch (LPS), fusible plug, circuit breakers and fuses.

a. Pressure Switches

High Pressure Switch (HPS)

During the air conditioning cycle, compressor clutch operation will automatically stop if the HPS switch contacts open due to an unsafe operating condition. Opening HPS contacts de-energizes the compressor clutch shutting down the compressor. The high pressure switch (HPS) is installed at the compressor assembly. See paragraph 1.3 for specifications.

Low Pressure Switch (LPS)

The low pressure switch is installed on the compressor assembly and opens on a pressure drop to shut down the system when a low p ressure condition occurs. See paragraph 1.3 for specifications.

Defrost Mode

Opens Compressor Output at: 28° F(-2.2°C) Closes Compressor Output at: 32° F(0°C)

The ambient tem p erature sensor measures the condenser inlet air temperature. These settings protect the compressor from damage caused by operation at low pressures.

d. Unloader Operation

The compressor is equipped with two unloaders to allow compressor operation at 33%, 66% or 100% capacity.

Low Pressure Control

Energizes Unloader Output 1 (Unloads) at: 25 psig (1.7 bars) De-energizes Unloader Output1 (Loads) at: 32 psig (2.2 bars)

Energizes Unloader Output 2 (Unloads) at: 21 psig (1.4 bars) De-energizes Unloader Output1 (Loads) at: 28 psig (1.9 bars)

b. Fuses and Circuit Breakers

The Relay Bo ard is protected against high current by an OEM supplied circuit breaker or fuse located in the bus battery compartment (100 Amp for 24 VDC systems is recommended). Independent fuses and circuit breakers protect electrical circuits from high current conditions. During a high current condition, the circuit protection may open.

c. Ambient Lockout

Auto Mode

Opens Compressor Output at: 43° F(6.1°C) Closes Compressor Output at: 47° F(8.3°C)

High Pressure Control (below 87 F (30.8C)

Energizes Unloader Output (Unloads) at: 300 psig (20.7 bars)

High Pressure Control (above 92 F (33.6C)

Energizes Unloader Output (Unloads) at: 320 psig (23.4 bars)

In response to the high pressure conditions above, the unloader remains energized for 2 minutes. Once the pressures return below the parameters listed, the unloader circuit will de-en ergize.

1--4

1.6 AIR CONDITIONING REFRIGERATION CYCLE

When air conditioning (cooling) is selected by the controller, the unit operates as a vapor compression system using R-134a as a refrigerant (See Figure 1-2 refrigerant flow diagram). The main components of the system are the A/C compressor, air-cooled condenser coils, filter-drier, thermostatic expansion valve, liquid line solenoid valve and evaporator coils.

The compressor raises the pressure and the temperature of the refrigerant and forces it into the condenser tubes. The condenser fan circulates surrounding air (which is at a temperature lower than the refrigerant) over the outside of the condenser tubes. Heat transfer is established from the refrigerant (inside the tubes) to the condenser air (flowing over the tubes). The condenser tubes have fins designed to improve the transfer of heat from the refrigerant gas to the air; this removal of heat causes the refrigerant to liquefy, thus liquid refrigerant leaves the condenser and flows to the filter-drier.

The refrigerant passes through a filter-drier where a desiccant keeps the refrigerant clean and dry.

From the filter-drier,the liquid refrigerantthen flows through the liquid line to the sight-glass and then to the thermostatic expansion valve. The thermal expansion valvereduces pressure and temperature of the liquid and meters the flow of liquid refrigerant to the evaporator to obtain maximum use of the evaporator heat transfer surface.

The low pressure, low temperature liquid that flows into the evaporator tubes is colder than the air that is circulated over the evaporator tubes by the

evaporatorfans. Heat transferis established from the evaporator air (flowing over the tubes) to the refrigerant (flowing inside the tubes). The evaporator tubes have aluminum fins to increase heat transfer from the air to the refrigerant;therefore the cooler air is circulated to the interior of the bus.

The transfer of heat from the air to the low temperature liquid refrigerant in the evaporator causes the liquid to vaporize. This low temperature, low pressure vapor passes through the suction line and returns to the compressor where the cycle repeats.

1.7 HEATING CYCLE

Heating circuit (See Figure 1-3) components furnished by Mobile Climate Control include the heater cores and solenoid operated heat valve. Components furnished by the bus manufacturer may include a water temperature switch (WTS), boost water pump and floor blower convectors.

The controller automatically controls the heat valves during the heating mode to maintain required temperatures inside the bus. Engine coolant (glycol solution) is circulated through the heating circuit by the engine and an auxiliary boost water pump. When the heat valve solenoids are energized, the valves will open to allow engine coolant to flow through the heater coils. The valves are normally closed.

NOTE: In order to ensure water is entering the heater coils sufficiently heated, it is suggested that the OEM supplied Water Temperature Switch (WTS), (If equipped) close on temperature rise at 105°F (40.5°C).

1--5

T-367Rev. 05/2015

CONDENSER SECTION

1. High Pressure Switch

2. Low Pressure Switch

3. Discharge Service Valve

4. Suction Service Valve

5. Discharge Check Valve

6. Service Port, (High Side)

7. Service Port, (Low Side)

8. Pressure Transducer (SPT)

EVAPORATOR SECTION

9. Thermal Expansion Valve (TXV)

10. Liquid Line Sight Glass

11. Pressure Transducer (DPT)

12. Filter Drier Service Valve

13. Filter Drier

14. Liquid Li ne Solenoid Valve

15. Receiver Tank

16. Fusible Plug

Figure 1-2 Refrigerant Flow Diagram

1--6

HT HP SHV

HT HP SCL LT LP SM LT LP SHV

CONDENSER SECTION

MAIN ENGINE

RADIATOR

Boost Pump

INLET

EVAPORATOR SECTION

Figure 1-3 Heat Flow Diagram

OUTLET

Heat Valve (N.C.)

1--7

T-367Rev. 05/2015

SECTION 2

OPERATION of MCC EcoXcel DRIVER DISPLAY

2.1 General Description

Operation of the MCC Eco Xcel unit is controlled through the MCC Driver's display.

When the MCC Displayis used to control operation, the Mode selection is selected using the “Mode” button ( item 3) on display, shown in Figure 2-1.

Ability to view system pressures, sensor temperatures, component status, etc. is available Through the MCC Display Module.

2.2 STARTING, STOPPING AND OPERATING INSTRUCTIONS

The MCC Drivers Display Module is marked with international symbols (See Figure 2-1).

Before starting, electrical power must be available from the bus power supply.

A circuit b reaker/fuse in the battery com partment passes power for the clutch, evaporator and condenser assemblies.

2.2.1 Starting

a. If the engine is not running, start the engine.

b. When the 24VDC power is applied, the driver dis

play will be ready to except req u est for system op eration. Press the On/Off key (Item 1, Figure 2-1) on the displayto triggerthe start up sequence, con trolled by the MCC D rivers display module.

2.2.2 Stopping

Toggling the On/Off key (Item 1, Figure 2-1) on the display again will stop the system operation controlled by the MCC D rivers display module.

Figure 2-1 Driver Display Module- Control Layout

1. On/Off

2. Temperature Set Point Control

3. Cursor and Mode Selection

4. Information/Display Settings

5. Alarm Indicator

2--1

T-367Re v. 05/2015

1. Operation Mode

2. Temperature Set Point

3. Fan Speed Indicator

4. Interior/Exterior Temperatures

5.. Alarm Indicator Symbol

Figure 2-2 Driver Display Module- Display Layout

2.3 SEQUENCE OF OPERATION

2.3.1 Function of Keys when “Engine On” and controller

active:

a. On/Off Key - Turns HVAC unit On or Off, un

less OEM supplied switches are installed. It also is used to exit diagnostic men u .

b. Temperature Set Point Control Keys -These

buttons increase or decrease the tem perature set point for the passenger area HVAC unit.

c. Cursor/Mode Selection Key- Used to toggle

through parameter settings in diagnostic mode or set the operating mode to Auto, Heat, Vent, Cool, and Defrost in normal display mode.

d. Information/Display Settings Key - Allows ac

cess to display settings and system diagnostics.

2.3.2 Illuminating Indications (Display)

With “Engine-On” and Controller active by the On/Off button.

NOTE:

Depending on Customer specification, the modes of operation may be controlled strictly through manual switches provided in the driver's area.

2--2

T-367Rev05/2015

2.4 BASIC OPERATING INSTRUCTIONS

When the engine is running, press the On/Off buttonondisplay.

2.4.1 Display

When the unit is ON, the display shows the interior set point temperature, current blower speed setting, mode selection and Interior/Exterior temperatures.

2.4.2 Interior Set Point Temperature Control

Press the UP (Red) or Do wn (Blue) keys to set the desired interior temperature.

The t em perature can be adjusted between 62° F(16° C) and 82° F(28° C).

2.4.3 Blower Speed Setting

Blower speed operation will be set for high or low speed operation automatically through software, or can be set through manual switches provided at the driver area.

2.4.4 Mode Selection Descriptions

a. Auto - In the auto mode, the ECC node willadjust

the individual components to maintain the desired set point temperature.

In the auto mode, the evaporator fans will operate in an “Ultra” high speed to achieve desired set point faster, when the interior temperature is greater than 5.4°F (3°C), from desired set point.

In the auto mode, the A/C system will continue to operate when set point is reached, and will ener gize the boost pump and de-energize the heat solenoid valve to maintain temperature. This is re ferred to as Reheat mode, to provide additionalde humidification of interior space.

The reheat mode will be disabledif the outsideam bient air temperature is below 43° F(6.1° C).

b. Cooling - In the cooling mode, the Compressor,

condenser fans and evaporator fans will be ener gized. The heater solenoid valve will be energized (closed), to provide full cooling.

The compressor and condenser fans will be de-en ergized 2 degrees F below set point. The evaporat or fans willcontinue to operateto circulateinterior air.

c. Heating - In the heating mode, the compressor

and condenser fans will remain de-energized. Evaporator fans will be energized. The boost pump willbe energized,andthe heat solenoidvalve will be de-energized (opened), to allow engine coolant to flow through the heater coils. If the in terior temperature is more than 5° F(3° C) below set point, the floor blowers (if equipped) will also be energized.

d. Defrost - In the defrost mode, the boost pump

will be energized to pro vide engine coolant flow to the drivers unit to allow defogging of the wind shield.

Defrost Override - In the event the main HVAC system is “OFF”, the ability of the OEM to provide a signal to the controller to energize the Boost Pump to provide engine coolant flow for the Drivers Defroster is provided.

e. Vent- In the vent mode, the evaporator blowers

are operated to circulate air in the bus.

2.4.5 Capacity Control “Ladder” Diagrams

Ladder diagrams showing system operational control logic for Auto/ Cool (Reheat system), and Heat, can be seen in Figure 2-3.

2--3

T-367Re v. 05/2015

3°F

COOL

4 CYLINDER

3°F

2°F

1°F

SETPOINT

-- 1 °F

-- 2 °F

-- 3 °F

-- 4 °F

-- 5 °F

COOL

2CYLINDERS

REHEAT DUTY CYCLE

0-- 100%

2 CYLINDERS

HEAT

2°F

1°F

SETPOINT

-- 1 °F

-- 2 °F

-- 3 °F

-- 4 °F

-- 5 °F

VENT

HEAT

FLOOR BLOWERS

OFF

HEAT

WITH

FLOOR BLOWERS

AUTO/COOL

(Reheat)

Figure 2-3 Capacity Control Ladder Diagrams

2--4

HEAT

T-367Rev05/2015

2.4.6 Display Settings

To adjust display settings, from the main menu:

c. To adjust settings, press the up or down cursor

keys to scroll to desired parameter (Item 3 in Figure 2-1).

a. Press the “Information” button to enter the

“View” screen (Item 4 in Figure 2-1).

b. Press and releaseboth “Temperature Control UP”

and “Cursor UP” buttons (Items 3 in Figure 2-4) to access the display set- up screen.

Main Menu Screen

Temperature Control UP

d. To adjust settings, press the up or down temperat

ure control keys to scroll to adjust parameter

e. After adjustment, press “Information” button

(Item 4 in Figure 2-1) to exit set-up screen.

Info Button

Cursor UP

View Screen

Display Set-Up Screen

Figure 2-4 HVAC DISPLAY SETTINGS

2--5

T-367Re v. 05/2015

+ 43 hidden pages

MCC 50-2104, T50-2112 Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual