Duo-Therm 39125, 39424, 59528.601, 59529.601, 59530.601 Service Manual

...

AIR CONDITIONER & HEAAIR CONDITIONER & HEA

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AIR CONDITIONER & HEA

AIR CONDITIONER & HEAAIR CONDITIONER & HEA

T PUMPT PUMP

T PUMP

T PUMPT PUMP

SERVICE MANUSERVICE MANU

SERVICE MANU

SERVICE MANUSERVICE MANU

This Service Manual is the result of the dedication of The Dometic Corporation and its engineers to providing service people the necessary instructions for making accurate analysis of certain conditions. Provided is a comprehensive guide designed to lead a qualified mechanic through the Service Manual to locate and solve symptoms that may occur. Dometic continues their commitment to providing the most up to date information about servicing Duo-Therm Air Conditioners and Heat Pumps.

ALAL

Table of Contents

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Section Page

Installation ......................................................................... A.................................. 1

AC Power Requirements ............................................... A1 ................................ 1

DC Power Requirements .............................................. A2 ................................ 1

Field Wiring ................................................................... A3 ................................ 1

Breaker ......................................................................... A4 ................................ 2

Airbox ............................................................................ A5 ................................ 2

Ducting System ............................................................. A6 ................................ 2

Roof Top Units ........................................................ A6a .............................. 2

Basement Units ...................................................... A6b .............................. 9

Thermostat Location ..................................................... A7 .............................. 12

Operation ........................................................................... B ................................ 14

Air Conditioners ............................................................. B1 .............................. 14

Mechanical Controls ............................................... B1a ............................ 14

Bi-Metal Control System ......................................... B1b ............................ 14

Analog Control System ........................................... B1c ............................ 15

Comfort Control Center System .............................. B1d ............................ 16

Heat Pumps .................................................................. B2 .............................. 22

Mechanical Controls ............................................... B2a ............................ 24

Bi-Metal Control System ......................................... B2b ............................ 24

Analog Control System ........................................... B2c ............................ 25

Comfort Control Center System .............................. B2d ............................ 26

Components ...................................................................... C ................................ 27

Motors ........................................................................... C1.............................. 27

Capacitor, Fan/Run ....................................................... C2.............................. 28

Capacitor, Start .............................................................. C3 .............................. 28

PTCR Device or Start Relay .......................................... C4 .............................. 29

Compressor .................................................................. C5 .............................. 29

Overload Protector ........................................................ C6.............................. 30

Cold (Freeze) Control .................................................... C7.............................. 30

Electric Heat Strip.......................................................... C8.............................. 30

Selector Switch ............................................................. C9 .............................. 31

Changeover Thermostat ............................................... C10 ............................ 32

Remote Sensor ............................................................. C11 ............................ 32

Ambient Sensor ............................................................ C12 ............................ 33

Reversing Valve ............................................................ C13 ............................ 34

Transformer .................................................................. C14 ............................ 34

Fuse .............................................................................. C15............................ 34

Relay ............................................................................. C16............................ 35

Printed Circuit Board ..................................................... C17 ............................ 38

Thermostat .................................................................... C18 ............................ 42

Cable Assembly ............................................................ C19 ............................ 52

Sealed System .............................................................. C20 ............................ 55

Wiring ........................................................................... C21 ............................ 58

Other ............................................................................. C22 ............................ 59

Roof Gasket .................................................................. C23 ............................ 60

Configuration ..................................................................... D................................ 60

Symptom/Cause Chart ...................................................... E................................ 80

Roof Mounted Heat Pumps ........................................... E ................................ 80

Basement Heat Pumps ................................................. E ................................ 93

Roof Mounted Air Conditioners ..................................... E .............................. 102

Basement Air Conditioners ............................................ E............................... 116

Section A - Installation

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A1. AC Voltage

The unit is a 115VAC, 60Hz appliance. The proper operating range is between 103 and 126.5 volts AC. The voltage reading should be taken at the unit power supply leads. One test should be performed when the unit is turned OFF and another with it running under load. If the voltage is not within the proper operating range, it must be corrected before operation of the unit.

This is an energized circuit. Shock can occur if not tested properly. Testing to be done by a qualified service technician.

Check for proper AC volts at the connections at the units electronic control box on roof mounted units and at the connections at the electric box on basement units.

The dual units (Models 39224 and 39424) have two AC volt circuits. Verify that Circuit 1 is wired into CIR 1 terminal block and Circuit 2 is wired into CIR 2 terminal block. Check for proper AC volts at each terminal block.

A1a. AC Control Voltage

AC control voltage is supplied by the transformer for the control circuits on the following units: 39025.XXX,

39035.XXX and 39045.XXX. Se Section C14- Transformers on page 34.

If a furnace is to be operated by the Analog Control System, the furnace thermostat leads are connected to the blue/white striped wires out of the Analog Control Box. The furnace wires can be connected to either wire as polarity is not important. DC voltage is required by the Analog Control Board on one of the two wires for furnace operation.

A2b. Comfort Control Center System

A DC volt supply is required for the operation of the Comfort Control Center. The operational range is 10 to 30 volts DC. If DC volts are outside of the operating range, you could experience improper or erratic operation. To check DC volts, first check the incoming DC volts between the red (+) positive and black (-) negative, at the connections on the Comfort Control Center control box on roof top units or at the connections at the electric box of basement units.

A3. Field Wiring

If the unit’s compressor or fan fails to operate, chances are it is not receiving proper power. Be sure the power cord is plugged in and fuses ore breakers are ope.

Note: Many customers use extremely long power cords that are undersized. If possible, ask the owner to hook up the RV just like it was when the problem occurred. See FIG. A2

FIG. A2

A2. DC Volts

On certain models of electronic controlled air conditioners and heat pumps, DC volts must be supplied to the control board. The operational range is 10 to 16 VDC. If the DC voltage is below 10 VDC, you could experience improper operation of the components within the main board.

A2a. Analog Control System

A DC voltage supply is wired to the control board. The operating range is 10-16 Volts DC, with a maximum current draw of 0.250 Amps.

To check DC volts, first check the voltage between the red (+12) positive and black (-12) negative, at the connections on the Analog Control Box on the roof top unit.

FIG. A1

Make note of the wire size and compare it to the chart for wire sizing. See Section A1a - AC Control Voltage.

CURRENT WIRE SIZE

AMPS 16 14 12 10 8 6

5 47 76 121 192 216 486

10 38 60 96 153 243

15 25 40 64 102 162

20 30 48 76 121

LENGTH IN FEET

Section A - Installation, cont’d.

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A6a. Roof Top Units

A4. Breaker

A6. Ducting

A6a. Rooftop Units

Make sure that the power supply to the unit is disconnected before performing any work on the unit to avoid the possibility of shock injury or damage to the equipment.

The unit is to be protected by a time delay fuse or HACR (heating, air conditioner, refrigerator) breaker. By taking an amp reading at the unit AC voltage supply line, you can determine if the breaker is tripping prematurely. Place a clamp-on type ammeter around the black wire between the unit and breaker. Turn ON the unit and record the amp draw. If the breaker trips before the rated amperage, replace the breaker.

MODELS CIRCUIT PROTECTION

T.D. Fuse HACR Breaker

39125 (Basement) 15 amp 15 amp 39325 (Basement) 20 amp 20 amp 39224 (Basement)- Circuit 1 15 amp 15 amp

- Circuit 2 15 amp 15 amp

39424 (Basement)- Circuit 1 15 amp 15 amp

- Circuit 2 15 amp 15 amp

All Rooftop Units 20 amp 20 amp

59528.601 15 amp 15 amp

59529.601 15 amp 15 amp

59530.601 15 amp 15 amp

A5. Air Box

Improperly installed, the air box can be a source of cooling problems. The air box must be sealed to the ceiling template to prevent the mixing of discharge and return air. This will cause short cycling or frost formation on the inside coil On heat pumps, recirculation can cause the high side pressure to build, tripping the overload and/or breaker. In some instances, the ceiling template is bent when the anchor bolts are overtightened, causing gaps between the air box and the ceiling template. These gaps can be sealed with aluminum tape or a closed cell foam weather strip. The duct connecting the air conditioner or heat pump must be air tight. Use aluminum tape to seal the joints. The thermostat sensing bulb must be properly located to control temperature. If the sensing bulb is left curled against the side of the electric box or used as a ground connection, improper operation will occur. Relocate the sensing bulb in its proper place as indicated in the Installation and Operating Instructions. Check the air filters and clean.

Sizing and Design

The installer of this air conditioner system must design the air distribution system for his particular application. Several requirements for this system MUST be met for the air conditioner to operate properly. These requirements are as follows:

Roof cavity thickness must be between 2.00" and 5.50". This distance is measured between roof and ceiling surface.

The total cross-sectional discharge area of the outlet ducts from the plenum area under the air conditioner must be as follows:

1. 579 & 600 Series 17.5 sq. in.

2. 591, 595 & 630 Series 21.0 sq. in.

Duct Sizing Requirements as Follows:

Duct Depth (591/595/630 Series) 1-1/2" 2-1/4"

(579/600 Series) 1-1/4" 2-1/4" Duct Width 7" — — Total Duct Length 12 ft. 36 ft. Duct Length (short run) 1/3 Total Length

Distance from Duct End 5" 8" Distance from End of Elbow 15" — — Distance between Registers 24" — — Total Number Required/AC 4 8 Number Required per Run/AC 2 — — Free Area per Register 14 sq. in.— —

The duct material must meet or exceed any agency or RVIA Standard that may be in existence at the time the RV is produced.

It is the responsibility of the installer of this system to ensure the ductwork will not collapse or bend during or after the installation.

All discharge air ducts must be properly insulated to prevent condensation from forming on their surfaces or adjacent surfaces during operation of the air conditioner or heat pump. This insulation must be R-7 minimum.

Note: The Dometic Corporation will not be held liable for roof, structural or ceiling damage due to improperly insulated or sealed ductwork.

Return air opening must have 40 sq. in. minimum free area including the filter.

Min. Max.

Return air to the air conditioner must be filtered to prevent dirt accumulation on air conditioner cooling surface.

A6a. Roof Top Units

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Section A - Installation, cont’d.

Total System Pressure must be between the following:

0.55 to 0.90 in. W.C. for 579 Series

0.40 to 1.10 in. W.C. for 591, 595 & 630 Series

0.12 to 0.65 in. W. C. for 600 Series

This is determined with the air conditioner blower operation on high speed and return air filter and grille in place.

The Dometic Corporation recommends the basic configuration shown below for installing this Air Conditioner System. We have found by testing that this configuration works best in most applications of the Air Conditioner/Heat Pump System.

It is the responsibility of the installer of this system to review each RV floor plan and determine the following:

A. Duct Size B. Duct Layout C. Register Size D. Register Locations

E. Thermostat Location These items must be determined in conjunction with the Air Distribution System Sizing and Design Requirements listed.

Note: Alternate configurations and methods may be used which still allow the air conditioner to operate properly. However, these alternate configurations and methods must be approved by The Dometic Corporation in writing.

The following instructions are based upon the use of Dometic Return Air Kit. The electronic control kit has

mounting bolts supplied for use with this Kit. See FIG. A3.

Before preparing the ceiling opening, the type of system options must be decided upon. If a remote sensor is to be used, provisions must be made for it. If the load shed option (Energy Management System feature) is to be used, wires must be run from the load shed control to the Dometic A/C. If a furnace is to be connected, wires must be run from the furnace to the Air Conditioner.

The 14-1/4" x 14-1/4" (±1/8") opening must be framed to seal off the roof cavity. Holes used to route electrical wiring should be sealed. The 14-1/4" x 14-1/4" (±1/8") open-

ing is part of the return air duct and must be finished in accordance with NFPA Standard 501C, Standard for Recreational Vehicles, Section 2-7.

The most commonly found installation problem is the improper sealing of the 14-1/4" x 14-1/4" (±1/8") opening in the roof cavity. The cooled discharge and warm return air are mixed in the roof cavity and produce conditions that are excellent for frost production.

Even the best framing job will not stop frost from occurring if the cold air discharge is allowed to enter into the return air portion of the 14-1/4" x 14-1/4" (±1/8") opening. See FIG. A4.

FIG. A4

Duo-Therm’s return air kits are designed to be installed tightly to the bottom of the base pan and ceiling template. Insulation supplied in the kit not only stops condensation from forming on the divider plate, but prohibits air leaks as well. The insulation is purposely oversized to be attached to the sides of the 14-1/4" x 141/4" (±1/8") opening and the base of the air conditioner and ceiling template. Make sure the data plate does not get covered with insulation. See FIG. A5.

FIG. A5

FIG. A3

TOTAL OUTLET AIR AREA MINIMUM:

17.5 sq. in. - 579 & 600 Series

21.0 sq. in. - 590 & 595 Series

DUCTS MIN. MAX.

DEPTH (590 & 595 Series) 1-1/2" 2-1/4" (579 & 600 Series) 1-1/4" 2-1/4" WIDTH 7" — — TOTAL LENGTH 12' 36'

AIR CONDITIONER

If a Remote Temperature Sensor is to be used, (Comfort

REGISTERS

4 MIN. — 8 MAX. (Per A/C) 14 SQ. IN. FREE AREA PER REGISTER

14 INCH ROOF OPENING

ROOF RAFTERS

THE MINIMUM SHORT DUCT RUN MUST EQUAL 1/3 OF TOTAL DUCT LENGTH

VEHICLE FRONT

REAR REMOTE SENSOR (Required with Second Air Conditioner)

14-1/4" x 14-1/4" (±1/8”) OPENING

OPTIONAL FURNACE

FURNACE 2 WIRES

OPTIONAL FRONT REMOTE SENSOR

12V DC INPUT 2 WIRES

4-CONDUCTOR CONTROL CABLE

BREAKER BOX

115V AC REAR A/C

4-CONDUCTOR CONTROL CABLE

115V AC FRONT A/C

FURNACE 2 WIRES

DOMETIC COMFORT CONTROL CENTER

Section A - Installation, cont’d.

FRAME

14-1/4" (±1/8”)

OPENING

AC POWER SUPPLY WIRE

DUCT

FRAME

CCC, CONTROL CABLE(S) or 7-Wire Analog Cable

LOW VOLTAGE WIRES:

12VDC Furnace Load Shed Sensors

DUCT

ROOF

INSULATION

DUCT TO REAR

CEILING

DUCT TO FRONT

14-1/4" (±1/8”)

OPENING

INSULATION

SIDE VIEW

(TOWARD BACK OF RV)

TOP VIEW

(BACK OF RV)

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A6a. Roof Top Units

Control Center configuration, page 16) the connector end must be routed to the roof opening of the system which it will control. Make sure that at least 15" of the sensor cable extends into the roof opening. If a furnace is to be controlled by the system, the two furnace thermostat leads must be routed to the roof opening of the air conditioner that will control it. Make sure at least 15" of the furnace thermostat wires extend into the roof opening. If an Energy Management System - EMS (load shed) is to be used with the control, two wires must be routed to the roof opening of the zone to be managed. The signal required for this function is a normally open relay contact. When the EMS calls for the compressor to shut off, the relay contacts should close. Make sure that at least 15" of the EMS wires extend into the roof opening.

DOMETIC COMFORT CONTROL CENTER

FIG. A6

Route a copper 12 AWG, with ground, 115 VAC supply line from the fuse or circuit breaker box to the roof opening. a. This supply line must be located in the front portion of

the 14-1/4" (±1/8") opening.

b. The power supply MUST be on a separate Time Delay

Fuse or HACR Circuit Breaker.

c. Make sure at least 15" of supply wire extends into the

roof opening. This ensures easy connection at the Junction Box.

d. Wiring must comply with all National, State and Local

Wiring Codes.

e. Use a steel sleeve and a grommet or equivalent meth-

ods to protect the wire where it passes into the open-

ing. Route a dedicated 12 VDC supply line (18-22 AWG) from the RV’s Converter or Battery to the roof opening. a. This supply line must be located in the front portion of

the 14-1/4" (±1/8") opening. b. Make sure that at least 15" of supply wire extends into

the roof opening. c. In a multiple zone installation, this wiring is required in

only one of the 14-1/4" (±1/8") openings. Route a 4-conductor telephone cable from the Comfort Control Center™ mounting position into the 14-1/4" (±1/ 8") roof opening. Make sure that at least 15" of the wire extends into the roof opening and 6" extend from the wall at the mounting position of the Comfort Control Center™. In the event that other A/C’s are to be installed (additional zones) and additional 4-conductor telephone cable must be routed to the other A/C’s. Make sure that at least 15" of the wire extends into each of the roof openings. See FIG. A8.

FIG. A8

REAR REMOTE SENSOR

115V AC

FIG. A7

4-CONDUCTOR CONTROL CABLE

FURNACE 2 WIRES

4-CONDUCTOR CONTROL CABLE

BREAKER BOX

14-1/4" x 14-1/4" (±1/8”) OPENING

115V AC FRONT A/C

REAR A/C

FURNACE

OPTIONAL FRONT

12V DC INPUT 2 WIRES

REMOTE SENSOR

(Required with Second Air Conditioner)

14-1/4" x 14-1/4" (±1/8”) OPENING

OPTIONAL FURNACE

FURNACE 2 WIRES

A seven-conductor cable, 18-22 AWG is to be used for low voltage connections for Analog Controls. Choose the shortest, direct route from the 14" opening to the thermostat location selected. Consider where screws, nails or staples might contact the cable. See FIG. A8.

A6a. Roof Top Units

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Leave approximately 6" of cable extending through the wall for connection to thermostat. Leave approximately 10" of cable extending into the 14-1/4" (±1/8") opening for connection at Relay Kit. See A7 Thermostat Location, page

12.

If System if to control a gas furnace:

Route two 18 AWG from the furnace to 14-1/4" (±1/8") opening at this time.

FIG. A9

Section A - Installation, cont’d.

FIG. A10

In some installations, the OEM supplies their own return air kits. Sometimes both the return and the discharge air are ducted to and from the 14-1/4" x 14-1/4" (±1/8") opening. In some cases the bottom of the 14-1/4" x 14-1/4" (±1/ 8") opening is covered with ceiling material.

In this type of installation the 14-1/4" x 14-1/4" (±1/8") opening is divided. If the divider only fills to the thickness of the ceiling cavity, an air gap may be created both on the top and bottom of the thickness of the roof gasket, roof or ceiling material. A gasket, etc., must be used to fill up the open space to reduce recirculation. See FIG. A9.

Another method of connecting the discharge air to the coach’s main duct used Duo-Therm’s return air kit. It uses half of the 14-1/4" x 14-1/4" (±1/8") opening as a discharge plenum. If the duct opening is not clean, restriction of air can cause the coil to freeze. The opening of the duct should be as large as possible to make the air distribution better in the coach and reduce freeze-up. See FIG. A10.

The final method of installation dumps the discharge air directly into the RV’s main duct. The duct is routed through the 14-1/4" x 14-1/4" (±1/8") opening. A duct adapter is used to connect the air conditioner to the main duct. If this connection is not made properly, cold air can migrate back into the return air path and make conditions right for freeze-up. Be sure the duct adapter is sealed to the main duct and air conditioner. See FIG. A11.

FIG. A11

Section A - Installation, cont’d.

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A6a. Roof Top Units

Restrictions at the connection to the air conditioner is the most common cause, but blockage in the main duct runs can also cause freeze-up. Blockages commonly occur in the areas where the duct changes direction. Other obstacles that can cause a change in the duct (air) path include rafters, vent pipes, wire bundles, etc. See FIG. A12.

A good way to check for duct blockage is with a flashlight and a mirror. Remove ceiling register cover to allow a flashlight to be put in the duct and use a mirror to view the flashlight from the next register opening. A blockage will be visible in the mirror. See FIG. A12.

Duo-Therm has available a quick cool return air kit that will allow the cooled air to come directly out of the air conditioner. This will bypass any restrictions in the coach duct system. (Part No. 3105958.007 Shell White, 3105958.015 Polar White).

If the main duct in the vehicle is undersized, the volume of air flowing through the ducts will decrease. The coil temperature will also drop because not enough air is moving through it. The requirements for proper duct size are shown in FIG. A13.

Up to this point we have mainly covered the discharge side; however, restrictions of the return air can result in frost buildup. The Duo-Therm air conditioner requires a minimum of 40 square inches of FREE AREA.

FREE AREA - is the opening that remains in a grill or louvered panel after the restrictions are taken away. For example, an opening of 10 x 20 inches has 200 square inches. When this opening is covered with a grill that is 56 percent open, the FREE AREA is (200 x .56), 112 square inches.

Dometic return air kits are designed to have the correct free area; however some manufacturers use their own grills. If a manufacturer’s grill is used, it must use the above formula to make sure the return air is sufficient to reduce the chances for freeze-up. The filter material must also be considered as a restriction and subtracted from the FREE AREA. See FIG. A14.

Main ducts running through the 14-1/4" x 14-1/4" (±1/8") opening must leave space between the duct and return air grill or duct and bottom of the air conditioner. See FIG. A15, A16, A18.

FIG. A12

FIG. A13

TOTAL OUTLET AIR AREA MINIMUM:

17.5 sq. in. - 579 & 600 Series

21.0 sq. in. - 590 & 595 Series

AIR CONDITIONER

"S" PATTERN DUCT SYSTEM

DUCTS MIN. MAX.

DEPTH (590 & 595 Series) 1-1/2" 2-1/4" (579 & 600 Series) 1-1/4" 2-1/4" WIDTH 7" — — TOTAL LENGTH 12' 36'

FIG. A14

REGISTERS

4 MIN. — 8 MAX. (Per A/C) 14 SQ. IN. FREE AREA PER REGISTER

14 INCH ROOF OPENING

THE MINIMUM SHORT DUCT RUN MUST EQUAL 1/3 OF TOTAL DUCT LENGTH

ROOF RAFTERS

A6a. Roof Top Units

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Section A - Installation, cont’d.

FIG. A15

FIG. A17

FIG. A16

The gap between the top and the main duct to the bottom of the air conditioner should be a minimum of 1-1/2". See FIG. A17 & A18.

If the return air is ducted into the 14-1/4" X 14-1/4" (±1/8") opening, the duct must be equal to the 40 sq. inches that are needed by the air conditioner. Grill or registers used ing this duct must be equal to or greater than the duct in square inches.

The control system used by Duo-Therm Air Conditioner is designed with a low temperature switch that will shut off the compressor and allow air to flow through the coil to melt the frost. A properly operating cold control may allow a slight coating of frost to form on the evaporator coil before it turns off the compressor. If the cold control is not installed in its intended mounting locations, frost buildup can block all air flow through the evaporator coil and stop cooling inside the RV. The cold control has clips that allow it to be snapped onto the turn/bends of the evaporator coil.

See FIG. A20 & A21 for the correct location.

FIG. A18

Section A - Installation, cont’d.

Freeze Control with wires.

Coil Return Bend

kdkd

mfmf

Remove Hang Tag

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FIG. A19

A6a. Roof Top Units

Freeze Control Installation 579, 590 & 595 Series:

a. Snap freeze control into place on return bend located

at left side of evaporator coil as follows:

1) Locate “D” shaped notch in flange of evaporator coil.

2) Place the horseshoe end of freeze control through this notch and snap onto coil return bend. When positioned correctly, control wires will be 90° to direction of coil fin surface. See FIG. A20

Note: Freeze control is not used on heat pump coils. Some will have the “D” slot in the coil header.

579, 590 & 595 SERIES

FIG. A20

Mount the Freeze Control on left side of coil, with wires to the right side

Freeze Control Installation 600 Series:

a. Snap the freeze control into place on return end lo-

cated at right side of evaporator coil as follows:

1) Locate vertical return bend at lower right of evaporator coil.

2) Place the horseshoe end of freeze control onto this coil return bend and snap into place. When positioned correctly, control wires will be 90° to direction of coil fin surface. See FIG. A21.

Note: Freeze control is not used on heat pump coils, some

FIG. A21

600 SERIES

Install Freeze Control with wires as shown

A6b. Basement Units

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Section A - Installation, cont’d.

will have the “D” slot in the coil header.

A6b. Basement Units Models 39335 and 39125

Outdoor Section:

The Condenser coil is designed to have a fresh supply of air. If skirting is installed, allow a louvered grill with 330 square inches for supply air and a louvered grill on opposite side of coach (330 square inches) for discharge air.

Do not totally enclose the underside of the unit. Air circulation prevents heat from building under unit and your system will perform as designed.

The condenser section is a “blow-through” type. When the face of the coil is positioned behind a louvered or other type of restrictive opening, the FREE AREA of the opening must be at least 260 square inches.

Indoor Section: Clearances

The minimum clearances to the evaporator are zero inches to the bottom, top, left and right sides. Access to the electrical connections and drain connection must be provided when making the installation.

Be sure to allow sufficient room to service the electrical components.

Inlet Air

The evaporator section must have free access to room air. A minimum or 180 square inches of FREE AREA opening is required. Where the return air must be provided through louvers or mesh scree, the FREE AREA percentage of the material used shall be taken into consideration when making this determination. An example of how to determine FREE AREA is included under “Outdoor Sec-

tion”.

Grills and Registers Note: The return air grill must have the same square sur-

face as the coil face (15"H x 17"L).

For each air conditioning system, there must be a return grill to bring cabin air back into the unit. There must also be at least four discharge grills per unit.

Each return air grill must be filtered and accessible for cleaning and replacement.

Outlet Air

The central air conditioning unit is designed to use a discharge air duct with a static pressure of .10 to .25 inches water column. Proper duct size is necessary to maintain proper air flow without loss of static pressure and provide

30 percent to 60 percent open. Be certain that 260 square inches of FREE AREA is available to the face of the condenser.

Note: Service access must always be supplied either as clearance or as a defined access panel.

Mounting

Vibration eliminators are supplied to prevent the transmittance of vibration into the living area.

The air conditioning unit may be attached to rails beneath the vehicle, attached to the frame, or mounted directly to the floor of some vehicles.

Unit should be mounted with a tilt toward the rear (condenser) a half-bubble using a level. Unit rear should be 1/ 4" lower than the front.

Service Access

Be sure NOT to block the inlet or discharge air, or service access, when mounting.

good air circulation.

All air handling ducts must be properly insulated to prevent condensation forming on their surface during operating. A vapor barrier must also be supplied on the outer surface of the insulation to prevent moisture from traveling through the insulation and condensing on the cold ductwork. Note: If the air conditioning unit is attached to the central furnace, a damper must be installed at the furnace outlet to prevent cold air from circulating through the furnace heat exchanger, unless furnace is so equipped to utilize the builtin furnace relay.

Section A - Installation, cont’d.

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FIG. A22

2" X 12" INSULATED

90 SQ. IN. FILTERED (MIN. X 2)

DUCT (MIN.)

A6b. Basement Units

RETURN RISER X 2

2" X 10" CLOSEABLE GRILL (MIN. X 4))

SUPPLY AIR INSULATED

FLOOR CUTOUT 90 SQ. IN. MINIMUM

MIN. 180 SQ. IN. REQUIRED OPENING

Models 39224 and 39424

Condenser Section: Supply Air

The inlet of the condenser coil should be positioned so that it draws air from outside the vehicle. Special care must

be taken to prevent the discharge air from recirculating to the inlet of the condenser coil. Shields should be

added to ensure fresh air supply.

DISCHARGE CONDENSER AIR

ENCLOSED FLOOR JOIST

RETURN SYSTEM

-Risers use interior wall structure

-Using floor joists area for return to unit

-Each return grill is filtered

FIG. A23

FLOORING

FLOOR CUTOUT 90 SQ. IN. MINIMUM

Do not install the condenser where the fan will draw air from the exhaust of the vehicle, a motor generator set, transmission, road heat or ANY other heat producing source.

FIELD INSTALLED SHIELD THAT WILL PREVENT RECIRCULATION OF CONDENSER AIR.

The condenser section is a “draw-through” type. When the face of the coil is positioned behind a louvered or other type of restrictive opening, the FREE AREA of the opening must be at least 460 square inches.

A6b. Basement Units

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Section A - Installation, cont’d.

FREE AREA - is the opening that remains in a grill or lou-

vered panel after the restrictions are taken away. For example, an opening of 10 x 20 inches has 200 square inches. When this opening is covered with a grill that is 56 percent open, the FREE AREA is (200 x .56), 112 square inches.

Expanded and perforated metal grills in general vary from 30 percent to 60 percent open. Be certain that 460 square inches of FREE AREA is available to the face of the condenser.

Note: Service access must always be supplied either as clearance or as a defined access panel.

Clearances

The air conditioning unit clearances depend on:

1. Inlet air access used

2. Discharge air duct arrangement

3. Return air duct

4. Storage compartment location and design

A one (1) inch clearance is required on three (3) sides of the air conditioner if the top return is used. When using the side access for return, please allow a minimum of eight (8) inches for the return air duct. Access to the electrical connections must be provided when making the installation.

Evaporation Section: Inlet Air

The evaporation section must have free access to room air. A minimum of 128 square inches of FREE AREA opening is required. Where the return air must be provided through louvers or mesh screen, the FREE AREA percentage of the material used shall be taken into consideration when making this determination. An example of how to determine FREE AREA is included under Condenser Sec-

tion. See FIG. A24.

FIG. A24

RETURN SYSTEM

Return to be 6 ft. minimum from floor. Use wall structure for delivery to basement area. Return grille must be filtered.

Minimum return required per duct sizing for unit to perform within Engineering specifications. See Chart below:

DUCT SIZE MINIMUM MAX.

40 IN.

60 IN.

128 IN.

189 IN.

INSULATED DUCT

Minimum Maximum

40 IN.

(3 " depth Min.)

60 IN.

ADDITIONAL REQUIREMENTS:

Damper required in furnace. Vibration isolators should be used at each mounting point. 12 VDC required for Comfort Control operation.

REQ. SIZE MIN. QTY.

4 X 6 4

4 X 8 4

4 X 10 4

4 X 12 4

Condenser air outlet ( X2 in bottom) Must be isolated from condenser inlet air.

Condenser inlet air 2 places.

Supply Duct must be insulated. Supply Duct from air conditioner

must be equal to or greater in IN.2 as the floor ductwork.

Use 45 degree angle on inlets & outlets

Optional return area. May be used in conjunction with side return.

Electrical box access required. Each circuit, 15 AMP HACR

breaker

Section A - Installation, cont’d.

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Grills Note: The Return air grill must have the same square sur-

face as the return air duct.

1. For each air conditioning system, there must be a return grill to bring cabin air back into the unit. There must also be at least four discharge grills per unit.

2. Return grills must be mounted in front of the evaporator. If this is not possible, make sure there is nothing blocking the air flow from the grill to the evaporator.

3. The unit must have a return filter between the grill and the unit. This filter must be accessible for periodic cleaning.

Outlet Air

The air diffusion system, supplied by the installer, must be sized to maintain a static pressure at the blower outlet between .4 and 1.2 inches water column.

All air handling ducts must be properly insulated to prevent condensation forming on their surface during operation. A vapor barrier must also be supplied on the outer surface of the insulation to prevent moisture from traveling through the insulation and condensing on the cold ductwork. See section A6a - Rooftop Units.

A7. Thermostat Location

The thermostat location is very important for balanced temperature control in any RV.

Today’s interior design has become both cosmetically more appealing and more efficient in its use of storage space. These improvements have generated complex interior space requirements which, in turn, have caused many RV’s to become a maze for heating and air conditioning circulation.

FIG. A25

The proper location for the thermostat or remote sensor is 54" from the floor and on an inside wall. It should be located where it cannot be affected by heat from the sun, lamps, oven, etc., or other sources of draft. Locations close to entry doors and windows should be avoided. The discharge from registers blowing directly on the thermostat or remote sensor can cause the system to short-cycle and should be avoided. See FIG. A26.

FIG. A26 Examples of Bad Thermostat Locations

1, 3, 4 Near Heat Sources 2 Near Drafts or Heat source 5, 6 Near Drafts 7 On an Outside Wall

The heating system is usually mounted close to floor level and consists of one or more furnaces. The air conditioner(s) is mounted on the roof with a different air distribution system. It is very important to locate the thermostat and remote sensors in areas that have good air movement. This may be difficult because what works well for heating may not work well for air conditioning.

The thermostat or remote sensors must be placed in a location with good air movement. Placing a thermostat or sensor under a cabinet or in a corner will result in a large fluctuation in the temperature. See FIG. A25.

When the floor plan or interior design of an RV changes,

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Dometic suggests trying several locations for the thermostat or remote sensor to determine the best location for mounting. Both heating and air conditioning should be tested, especially when using different duct systems and the same thermostat. When the proper thermostat or remote sensor location is determined, this location can be used on other RV’s with the same basic plan. See FIG. A27.

FIG. A27 Example of Good Thermostat Location

(Interior Hallway Wall)

Section A - Installation, cont’d.

Section B - Operation

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B. Operation

The recreational vehicle manufacturer has equipped the vehicle with Duo-Therm’s Air Conditioner. The ability of the unit to maintain the desired inside temperature depends on the heat gain of the RV. Some preventative measures can be taken by the occupants of the RV to reduce the heat gain and improve the performance of the unit. During extremely high outdoor temperatures, the heat gain of the vehicle may be reduced by:

1. Parking the RV in a shaded area.

2. Using window shades (blinds and/or curtains).

3. Keeping windows and doors shut or minimizing usage.

4. Avoid use of heat producing appliances.

5. Starting the unit early in the morning and giving it a “head start” on the expected high outdoor temperatures will greatly improve its ability to maintain the desired indoor temperature.

The operating instructions can change from one model to another.

Be sure you are familiar with the proper operating instructions for the specific model of air conditioner you are diagnosing. An installation and operating manual is packaged with each air conditioner system.

B1. Air Conditioners

Mechanical Cooling Operation

Set the thermostat at the desired temperature level. Select the fan speed that best satisfies your needs. See FIG. B1.

a. HIGH COOL - Selected when maximum cooling

and dehumidification is required.

b. MED. COOL - Selected when normal or average

cooling is required.

c. LOW COOL - Selected when room is at desired

comfort level and needs to be maintained. Normally this speed is used for nighttime operation.

Note: The blower runs continuously to circulate air and maintain an even temperature. The compressor will come on as cooling is required to maintain the selected temperature level.

After shutting the air conditioner down with either selector switch or thermostat, wait at least two (2) minutes before restarting. This allows the refrigerant pressure to equalize and compressor to restart easily.

Fan Operation

This will circulate the air in your RV without cooling or heating. There are three positions: HIGH FAN, MED. FAN or LOW FAN to select from, depending upon personal choice.

B1a. Mechanical Controls

This type of air conditioner has an air distribution box that has a mechanical selector switch and thermostat installed in it.

Controls

The Selector Switch has eight positions including “OFF”. This controls fan speed, heating mode and cooling modes.

The Thermostat controls the temperature range from 65°F on the coldest side to 90°F on the warmest side. In the cooling mode, the compressor ON/OFF is controlled by the thermostat setting. See FIG. B1.

Heating Operation (With Optional Heat Kit Installed) Note: This electric heater will not replace a furnace for

heating your RV in cold weather. The intent is to remove the chill on cool days or mornings.

1. Turn the selector switch to “OPT. HEAT”.

2. The heater will come on and begin heating.

3. When desired temperature level in RV is reached, move the selector switch to off position or fan position.

Note: Thermostat does not control heater ON/OFF cycle. “OFF” Position turns unit off. See FIG. B1.

B1b. Bimetal Relay Controls

FIG. B1

This type of air conditioner has a wall mounted bimetal thermostat and a relay board that replaces the mechanical switch and thermostat on the mechanical units and replaces the main board and control board on the electronic units. Note: Remember to check the installation and operating instructions for the specific model of air conditioner you are diagnosing.

B1b. Bimetal Relay Controls

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Section B - Operation, cont’d.

Cooling Operation

Place the Temperature Set Lever to desired temperature level (located at top of thermostat). Select fan speed that best satisfies your needs: (upper right switch at bottom of thermostat). See FIG. B2. a. High Speed: Selected when maximum cooling and

dehumidification are required.

b. Low Speed: Selected when RV reaches desired com-

fort level and needs to be maintained. Normally this

speed is used for nighttime operation. Select Auto/ON Switch operation as follows: (Lower right switch at bottom of thermostat) a. Auto Position: Air conditioner fan runs whenever cool-

ing is required and stops whenever cooling is not re-

quired. b. On Position: Air conditioner fan runs continuously to

circulate air in RV. Set the Heat/OFF/Cool Switch to cool position (Located at lower left side of thermostat)

The air conditioner will now come on when cooling is required and cycle off when the temperature level selected is reached.

FIG. B2 1 = Temp Set Lever 2 = Auto/ON Switch 3 = System Switch 4 = Fan Speed

Special Feature

When thermostat:

Heat/Off/Cool Switch is in the OFF or HEAT position and Auto/On Switch is in the ON position, the air con- ditioner fan will run continuously to circulate the air inside the RV. See FIG. B2.

B1c. Analog Control System

In order to familiarize yourself with the operation of the Analog Control System, the following diagrams along with the accompanying text will explain all the functional characteristics of the system.

FAN

SYSTEM

COOL

OFF

FURNACE

HEAT PUMP

SYSTEM

COOL

OFF

FURNACE

HEAT PUMP

HEAT STRIP

AUTO

FURNACE

HEAT PUMP

FIG. B3

1. Temperature Set Lever

2. Fan Auto/On Switch

3. System Switch

4. Fan High/Low Switch

AUTO

SYSTEM

COOL

OFF

10 °C

FAN

AUTO

FAN

10 °C

Analog Control Cooling Operation

1. Place the Temperature Set Lever (1) to desired tem- perature level. See FIG. B3.

2. Select desired fan speed by moving the Fan Speed Switch (4) to : a. High speed: Selected when maximum cooling and

dehumidification are required.

Wait at least two (2) minutes before restarting the air conditioner after shutting off with either the Heat/OFF/Cooling Switch of the Temperature Set Lever. This allows the refrigerant pressure in the air conditioner to equalize and will allow the compressor to restart easily.

Heating Operation (If furnace is connected to Thermostat)

Set Temperature Set Lever to desired temperature level (located at top of thermostat). See FIG. B2. Set the Heat/Off/Cool Switch to heat position (located at lower left side of thermostat). See FIG. B2.

The furnace will now come on when heat is required and cycle off when temperature level selected is reached.

b. Low speed: Selected when RV reaches desired

comfort level and needs to be maintained. Normally this speed is used for night time operation.

3. Move the FAN Auto/On Switch (2): See FIG. B3 a. Auto Position: Unit fan runs whenever cooling is

required and stops whenever cooling is not required.

b. ON Position: Unit fan runs continuously to circu-

late air in RV. See FIG. B3.

4. Set the System Switch to cool position. The unit compressor will now come ON and cycle OFF when the temperature level selected is reached.

Furnace Operation (If furnace is connected to relay box.)

1. Set the Temperature Set Lever (1) to desired tem- perature setting. See FIG. B3

2. Set the System Switch (3) to furnace position. The

furnace will now come ON when heat is required and cycle OFF when the temperature setting selected is reached.

Section B - Operation, cont’d.

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B1d. Comfort Control Center

Analog Control Electric Heat Strip Operation (If unit is equipped with optional electric heat strip.)

1. Set the Temperature Set Lever (1) to desired tem- perature level. See FIG. B3.

2. Set the System Switch (3) to heat strip position.

3. Move the FAN Auto/On Switch (2): a. Auto Position: Unit fan runs whenever heat is

required and stops whenever heating is not required. See FIG. B3.

b. ON Position: Unit fan runs continuously to circu-

late air in RV. See FIG. B3.

4. Select desired fan speed by moving the Fan Speed Switch (4) to: a. High Speed: Selected when maximum air flow is

required. The discharge air will feel cool due to the maximum air flow. It is normally not used for heat strip operation. See FIG. B3.

b. Low Speed: Normally selected for heat strip op-

eration, because less air movement is needed for heat and discharge air is warmer. See FIG. B3.

5. Set System Switch (3) to the heat strip position. The unit’s heat strip will now come “ON” and cycle “OFF” when the temperature level selected is reached.

Continuous Blower Operation

1. Set the System Switch (3) to any position (including “OFF”). See FIG. B3.

2. Move the FAN Auto/On Switch (2) to the ON position, the unit fan will operate continuously at the fan speed selected by the Fan Speed Switch (4). See FIG. B3.

B1d. Comfort Control Center

The Comfort Control Center has been designed for you to easily operate all the air conditioning and gas heating appliances found in your vehicle from one location.

In order to familiarize yourself with the operation of the Comfort Control Center, the following diagram along with

FIG. B4

A. Liquid Crystal Display

the accompanying text will explain all the functional characteristics of the system. Liquid Crystal Display - The Comfort Control Center is equipped with a liquid crystal display (LCD) that identifies the mode of operation, the temperature set-point, the zone identification and the fan speed. The Comfort Control Center is designed to accept and control many varied air con-

B. Fan Speed Selector Button C. Mode Selector Button D. Temperature Selector Buttons E. Zone and Stage Selector F. On/Off Switch

ditioning and gas heating appliances. When you begin to first operate the Comfort Control Center, you will see that the LCD readout will only show the options available based on the appliances installed on your vehicle. An incandescent light will illuminate the LCD area when a selector button is pushed for easy reading at all times. See FIG. B4.

Fan Speeds - Possible available fan speeds are: LOW, MEDIUM, HIGH and AUTO. To select the desired fan speed,

momentarily depress the FAN push button. You will need to continue to depress and release the FAN button until the desired fan speed is shown in the LCD readout area of the Comfort Control Center. See FIG. B4.

Mode Selector Button - Modes of operation available are: OFF, FAN ONLY, COOL, HEAT PUMP, FURNACE, STAGE

and HEAT STRIP. Remember, the LCD readout will only show the options available based on the appliances installed on your vehicle. To select the mode of operation, momentarily depress the MODE push-button. You will need to continue to depress and release the button until the desired mode is shown in the LCD readout area on the Comfort Control Center. See FIG. B4

To determine the Comfort Control Center options available to you, depress and release the MODE push-button until it goes through all selections. See FIG. B4

Temperature Selector Buttons - The temperature setpoint range is from 40° to 99° Fahrenheit. Determination of Fahrenheit or Celsius standard is done at the time of your manufacturer’s installation of the Comfort Control Center. To set the temperature at your comfort level, simply depress and release the UP or DN push-button until the desired temperature is shown in the LCD readout area of the Comfort Control Center. See FIG. B4

Zone and Stage Selector Buttons - A ZONE is also es- tablished at the time of installation of the Comfort Control Center. If you have one air conditioner, you will have one ZONE. If the vehicle has more than one cooling system, depending on the manufacturing installation, you may have 2, 3 or 4 ZONES. Zones are defined and preset by the manufacturer. A zone is an area of cooling/heating which is controlled independently within that area, and regulated at the Comfort Control Center. A typical example of a two zone application would be a vehicle with two air conditioning systems, one in the front area (living room, kitchen) and one in the back section (bedroom and bath). The front area could be established as ZONE 1 and the back section ZONE 2. You can select the desired temperature and fan speeds for each zone independently, thereby keeping your bedroom cooler than the front portion of the vehicle. To determine the number of established zones in the vehicle, simultaneously depress the FAN and MODE push-buttons. ZONE 1 will be the first Zone to appear in the LCD readout. Continue to depress and release these buttons until you see ZONE 1 reappear. See FIG. B4.

B1d. Comfort Control Center

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Section B - Operation, cont’d.

ON/OFF Switch - The ON/OFF switch is located on the

lower right hand edge of the Comfort Control Center. Move the lever from side to side to change status. See FIG. B5.

General Information

The ability of the air conditioner to maintain the desired inside temperature depends on the heat gain of the RV. Some preventative measures taken by the occupants of the RV can reduce heat gain and improve the performance of the air conditioner. During extremely high outdoor temperatures, the heat gain of the vehicle may be reduced by:

1. Parking the RV in a shaded area.

2. Using window shades (blinds and/or curtains).

3. Keeping windows and doors shut or minimizing usage.

4. Avoiding the use of heat producing appliances.

Starting the air conditioner early in the morning and giving it a “head start” on the expected high outdoor ambient will greatly improve its ability to maintain the desired indoor temperature.

The manufacturer of this air conditioner will not be responsible for damage caused by condensed moisture on ceilings or other surfaces. Air contains moisture and this moisture tends to condense on cold surfaces. When air enters the RV, condensed moisture may appear on the ceiling, windows, metal parts, etc. The air conditioner removes this moisture from the air during normal operation. Keeping doors and windows closed when the air conditioner is in operation will minimize condensed moisture on cold surfaces.

This equipment must be serviced by qualified personnel and some states require these people to be licensed.

Fan Only Mode of Operation - See FIG. B4 & B5

1. Begin by placing the power switch on the lower right hand edge of the Control Center in the ON position. To do this, simply move the lever to the right.

2. Momentarily depress and release the MODE push- button until the FAN ONLY indicator on the Liquid Crystal Display (LCD) is illuminated.

3. Momentarily depress and release the FAN push- button until the desired fan speed indicator (LOW, MED, HIGH, AUTO) is illuminated. If your vehicle is equipped with a heat pump or a dual basement air conditioning system, your selection choice will be LOW, HIGH or AUTO.

4. After approximately 5 seconds, the selected fan speed will come on. The MODE and FAN speed you have selected will remain shown in the LCD area of the Control Center until you change your selection.

5. If the vehicle contains more than one ZONE, depress the FAN and MODE push-buttons simultaneously to select ZONE 2, and repeat procedures from step two above. Repeat entire procedure for each additional zone.

FIG. B5

Cooling Mode Operation - See FIG. B4 & B5

(To set cooling temperatures and fan speeds on Duo-Therm Air Conditioners and the cooling mode of Duo-Therm Heat Pumps.)

1. Momentarily depress and release the MODE push-button until the COOL indicator on the LCD is illuminated.

2. Depress and release the FAN push-button to select your desired fan speed.

3. Depress and release the UP push-button to increase the temperature or the DN push-button to decrease the desired temperature. The final selected SETPOINT will be displayed in the LCD area of the Comfort Control Center.

4. After a delay of approximately 2 minutes the air conditioner’s compressor will come on and the cooling process will begin. Once the room temperature reaches the selected SETPOINT, the compressor will cycle off. Once the Comfort Control Center senses the need for cooling, the compressor will restart in approximately two minutes. At this point, the fan will either: a. continue to operate in the single selected fan speed

or,

b. cycle OFF and ON with the compressor if the AUTO

fan speed has been selected.

If the vehicle has a dual basement air conditioner or dual heat pump system, the word STAGE (see stage operation, page 20) will be illuminated. Both of these units operate in two different stages, and the word STAGE will show when the second stage operation has been selected. To select the second stage, simultaneously depress the FAN and MODE push-buttons. See FIG. B4 & B5.

Section B - Operation, cont’d.

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B1d. Comfort Control Center

Fan Only Mode of Operation - See FIG. B4 & B6

1. Begin by placing the power switch on the lower right hand edge of the Control Center in the ON position. To do this, simply move the lever to the right.

2. Momentarily depress and release the MODE push-button until the FAN ONLY indicator on the Liq- uid Crystal Display (LCD) is illuminated.

3. Momentarily depress and release the FAN pushbutton until the desired fan speed indicator (LOW, MED, HIGH, AUTO) is illuminated. If your vehicle is equipped with a heat pump or a dual basement air conditioning system, your selection choice will be LOW, HIGH or AUTO.

FIG. B6

Cooling Mode Operation

(To set cooling temperatures and fan speeds on Duo-Therm Air Conditioners and the cooling mode of Duo-Therm Heat Pumps.) See FIG. B7.

1. Momentarily depress and release the MODE push-button until the COOL indicator on the LCD is illuminated.

2. Depress and release the FAN push-button to select your desired fan speed.

or,

b. cycle OFF and ON with the compressor if the

AUTO fan speed has been selected.

5. If the vehicle contains more than one ZONE, depress the FAN and MODE push-buttons simultaneously to select ZONE 2, and repeat procedures from Step 1. Repeat entire procedure for each additional zone.

Note: If set point is too low, the inside could freeze up.

FIG. B7

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Section B - Operation, cont’d.

Heat Pump Operation

(To set heating temperatures for vehicles equipped with a Duo-Therm rooftop or basement heat pump, see “Cooling Mode Operation”.) See FIG. B8.

1. Momentarily depress and release the MODE push-button until the HEAT PUMP indicator on the LCD is illuminated.

2. If you have not previously set your fan speed, you may do so by depressing and releasing the FAN pushbutton to select.

4. After a delay of approximately 2 minutes the heat pump’s compressor will come on and the heating process will begin. Once the room temperature reaches the selected SETPOINT, the compressor will cycle off. Once the Comfort Control Center senses the need for heating, the compressor will restart in approximately two minutes. At this point, the fan will either: a. continue to operate in the single selected fan speed

or,

b. cycle OFF and ON with the compressor if the AUTO

fan speed has been selected.

5. If the vehicle contains more than one ZONE, depress the FAN and MODE push-buttons simultaneously to select ZONE 2, and repeat procedures from Step 1 above. Repeat entire procedure for each additional zone.

Furnace Mode Operation

(If the vehicle is equipped with a gas furnace connected to the Comfort Control Center.) See FIG. B9

1. Momentarily depress and release the MODE push-button until the FURNACE indicator on the LCD is illuminated.

2. The Heat Pump fan does not operate in the FURNACE mode.

4. The Duo-Therm heat pump system will not operate when the Comfort Control System is in the FURNACE mode. For cooling, change MODE to COOL.

Note: When furnace mode is selected in any Zone, all heat pump units will terminate operation.

FIG. B9

FIG. B8

Section B - Operation, cont’d.

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B1d. Comfort Control Center

Heat Strip Mode Operation - See FIB. B10 (For Duo-Therm air conditioners with an electric heat strip.)

1. Momentarily depress and release the MODE push-button until the HEAT STRIP indicator on the LCD is illuminated.

2. The fan will operate in LOW, MED or AUTO. You will not be able to select HIGH speed when in the HEAT STRIP mode. Depress and release the FAN pushbutton to select desired speed.

3. Depress and release the UP push-button to increase the temperature or the DN push-button to decrease the temperature. The final selected SETPOINT will be displayed in the LCD area of the Comfort Control Center.

4. The electric heat strip will cycle ON and OFF per the temperature SETPOINT displayed. The fan will either: a. continue to operate in the selected fan speed or, b. cycle OFF and ON with the heat strip if the AUTO

fan speed has been selected.

FIG. B10

HEAT PUMP MODE - When HEAT PUMP mode is

selected, the fan will automatically run in the LOW speed. HEAT STRIP MODE - When HEAT STRIP mode is selected, the fan will automatically run in the LOW speed.

FAN ONLY MODE - In the FAN ONLY mode, the fan automatically runs in the LOW speed.

Refrigerant Compressor Time Delay

A time delay of approximately two minutes occurs any time the compressor is required to begin the cooling or heat pump cycle.

Power Interruption

In the event that power to the air conditioner or control is interrupted, the system will restart with the same settings you have previously set.

Zone Control

The Duo-Therm Comfort Control Center will operate cooling and heating appliances which the vehicle manufacturer has designed to heat or cool different areas (ZONES) of your RV. The Comfort Control Center will advise you if the vehicle has multiple ZONES, by showing ZONE 1, 2, 3 or

4 in the LCD readout.

Stage Control Operation

If the vehicle is equipped with a Duo-Therm Dual Base-

Auto Fan

When AUTO FAN is selected, the fan speed will be deter- mined by the mode you are in.

COOL MODE - In the COOL mode, which is the air conditioning mode, the fan will automatically select the speed depending upon the difference between the temperature SETPOINT and the room temperature. When that difference is: 8° or more The fan will operate on HIGH 4° to 8° The fan will operate on MED 4° or below The fan will operate on LOW

ment Air Conditioner or a Dual Basement Heat Pump, you have an air conditioning system that is designed to optimize comfort and running efficiencies. This is accomplished by providing an on-demand secondary stage of operation.

Note: The primary stage will continue to operate even if there isn’t electrical power available to run the second stage.

The Comfort Control Center simplifies this operation by allowing you to set the primary temperature set-point and the differential temperature set-point which activates the secondary stage. After turning on your Comfort Control Center, perform the following steps to set and activate the stage control operation. See FIG. B11.

1. Momentarily depress the MODE push-button until the desired mode of operation is selected. (FAN ONLY, COOL, HEAT PUMP)

2. Momentarily depress the FAN push-button until the desired fan speed indicator is illuminated (LOW, HIGH, AUTO)

B1d. Comfort Control Center

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Section B - Operation, cont’d.

FIG. B11

3. Momentarily depress the UP and DN push-button until the desired room temperature set-point is displayed.

This completes the setup for the primary stage of the Dual Basement Air Conditioner or Dual Basement Heat Pump. Next, you will set up the secondary stage.

To Set Up the Secondary Stage

1. Simultaneously depress and release the FAN and MODE push-buttons until the STAGE indicator on the

LCD is illuminated. See FIG. B12.

2. Momentarily depress the MODE push-button until the desired mode of operation for the second stage is selected (FAN ONLY, COOL, HEAT PUMP). Normally, the mode of operation is the same as the primary stage.

3. Momentarily depress the FAN push-button until the desired fan speed indicator is illuminated (LOW, HIGH, AUTO).

4. Momentarily depress the UP or DN push-button to set the desired differential temperature setpoint (0°F to 10°F). The secondary stage will run once the actual room temperature reaches the differential temperature setpoint. Example: Desired room temperature setpoint for the primary stage in the COOL MODE is set at 72°F; differential temperature setpoint is set at 5°F. The secondary stage will activate when the actual room temperature reaches 77°F (72°F + 5°F), and will continue to operate until the room once again becomes 72°F.

Aux. Heat - See FIG. B13 When in the HEAT PUMP mode, if the outside ambient temperature is measured to be below 24°F, the control will automatically select the FURNACE operation. When this happens, the AUX. HEAT and the HEAT PUMP indicators on the LCD will illuminate. Once the outside ambient temperature is measured above 34°F, the control will return to the HEAT PUMP operation. If your vehicle does not contain a furnace, and you have a Duo-Therm Heat Pump, once the outside ambient temperature goes below 24°F, the system will shut down until the outside temperature reaches 34°F, at which time the Heat Pump will resume operation.

FIG. B13

Defrost Cycle - See FIG. B14 This cycle is active during HEAT PUMP operation and al- lows the heat pump to operate down to 24°F. When the outside ambient temperature is less than 42°F and greater than 24°F, a defrost timing cycle will begin. The defrost timing cycle will allow operation of the heat pump for 40 minutes. The fan will the be shut off, the refrigerant flow reversed and run for 4-1/2 minutes, this is the DEFROST cycle. The refrigerant flow will then be returned to normal and after a 30 second delay, will continue until the temperature is greater than 42°F or until the temperature becomes less than 24°F, at which time the furnace will activate. (See Aux. Heat). During the defrost cycle, the DE-

FROST indicator on the LCD shall be illuminated.

FIG. B12

FIG. B14

Section B - Operation, cont’d.

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Reset

If the Comfort Control Center is not operational, inadequate data or no functions occur, reset the Comfort Control Center to factory settings. When a reset procedure is done, all previous program memory is removed. The factory setting of 72°F for cooling mode and 68°F for heating modes are entered.

To initiate a RESET, do the following in the order listed:

1. Turn control on to ensure annunciator data and light are present. If data and light are present, continue to next step.

2. Depress MODE switch to activate annunciator light.

3. Simultaneously depress the bottom two buttons (temperature UP and DOWN) and hold.

4. While holding these buttons down, depress the MODE button once and release.

5. Release the two buttons previously held down.

6. Depress the MODE button once again.

7. At this time the light should extinguish, and the mode should register “OFF”. If not, repeat Steps 2 through 6.

8. Retest system ensuring that all functions are present and operational.

FIG. B15

B2. Heat Pump

General Information

The roof-top heat pump was designed to operate in a MILD GEOGRAPHICAL AREA for heating where the heat loss is minimal. The heat pump was designed to operate down to an outside ambient temperature of 40°F. As long as the temperature remains below 40 degrees, the main furnace will heat your home. As the outside temperature increases to 45°F., the outdoor thermostat switches back to the heat pump circuit.

Note: Model 59126.501 does not have an outdoor thermostat. When outdoor temperature is at or below 40°F., use the main furnace to heat your home.

The advantages of the heat pump are:

1. User friendly; only one unit for both heating and cooling;

2. Heat pump heating uses campsite electrical hookup and saves on trips to refill L.P. tanks;

3. When used in mild climates where the outdoor temperature range is 40 degrees or higher, an LP furnace is not needed.

The heat pump operates in two different modes; cooling and heating.

The same mechanism is used for both cycles, but the travel or flow of refrigerant is reversed to change from cooling to heating. The items used to accomplish this are a compressor, an inside coil, an outside coil, capillary tube or tubes (the metering device/s), a series of copper lines (refrigerant grade tubing), a reversing valve, an air movement system (motor and wheel or blades), and refrigerant (R22).

The Cooling Mode

To cool the air inside a structure, heat is removed from the inside air and released to the outside air or ambient.

To accomplish this, first air flow is established to pass over both coils (inside and outside). Next, a refrigerant cycle is established to cause refrigerant (R22) to flow through both coils.

The refrigerant cycle starts at the compressor. Its function is to take the low pressure R22 vapor and discharge it as high pressure vapor. As the refrigerant (R22) is compressed, it gives off heat causing the discharge line to be quite warm or hot to the touch in hot weather.

The R22 high pressure vapor leaves the compressor through the discharge line and enters the reversing valve. The reversing valve routes the high pressure vapor to the outside coil. In the cooling mode, the outside coil is a condenser coil.

The high pressure R22 vapor enters the outside coil (condenser). Here it is cooled and condensed into liquid R22 by passing through the coil. The heat removed from the refrigerant is expelled to the outside air. The refrigerant

B2. Heat Pump

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Section B - Operation, cont’d.

leaves the outside coil as high pressure liquid.

As the high pressure liquid R22 leaves the outside coil (condenser) it passes through the small capillary tube or tubes. This is the metering or flow control device in the sealed system. It determines the amount and force of which the R22 enters the inside coil. It is imperative that the capillary tube’s length and diameter not be altered. If the tube is altered, the unit will not operate as efficiently as it should.

The high pressure liquid R22 enters the inside coil in a controlled amount from the capillary tube. When the liquid enters the low pressure atmosphere of the inside coil (evaporator) it evaporates into vapor. When the evaporative process takes place, heat is removed from the air flowing through the inside coil (evaporator). The air with the heat removed is returned to the inside of the structure via the air movement system (blower assembly).

From the inside coil (evaporator), the low pressure refrigerant (R22) vapor returns to the reversing valve. The reversing valve routes the low pressure vapor to the compressor through the suction line to start the cooling process again.

The Heating Mode

To heat the air inside a structure, heat is removed from the outside air or ambient and released to the inside air.

To accomplish this, first air flow is established to pass over both coils (inside and outside), Next, a refrigerant cycle is established to cause the refrigerant (R22) to flow through the coils.

The R22 high pressure vapor leaves the compressor through the discharge line and enters the reversing valve. The reversing valve routes the high pressure vapor to the inside could. In the heating mode the inside coil is a condenser coil.

The high pressure R22 vapor enters the inside coil (condenser). Here it is cooled and condensed into liquid R22 by passing through the coil. The heat removed from the refrigerant is expelled to the inside air. The refrigerant leaves the inside coil as high pressure liquid.

As the high pressure liquid R22 leaves the inside coil (condenser) it passes through the small capillary tube or tubes. This is the metering or flow control device in the sealed system. It determines the amount and force of which the R22 enters the outside coil.

It is imperative that the capillary tube’s length and diameter not be altered. If the tube is altered, the unit will not operate as efficiently as it should.

FIG. B16

COOLING MODE

FIG. B17

HEATING MODE

Section B - Operation, cont’d.

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B2. Heat Pump

The high pressure liquid R22 enters the outside coil in a controlled amount from the capillary tube. When the liquid enters the low pressure atmosphere of the outside coil (evaporator) it evaporates into vapor. When the evaporative process takes place, heat is removed from the air flowing through the outside coil (evaporator). The air with the heat removed is returned to the outside air (ambient) via the air movement system (blower assembly).

From the outside coil (evaporator), the low pressure refrigerant (R22) vapor returns to the reversing valve. The reversing valve routes the low pressure vapor to the compressor through the suction line to start the heating process again.

Operating instructions can change from one model to another.

Be sure you are familiar with the proper operating instructions for the specific model of heat pump you are diagnosing. An installation and operating manual is packaged with each heat pump system.

Fan Operation:

This will circulate the air in your RV without cooling or heating. There are two positions: HIGH FAN or LOW FAN to select from, depending upon personal choice.

Heating Operation Note: This heat pump will not replace a furnace for heating

your RV in cold weather. The intent is to remove the chill on cool days or mornings. When the outdoor temperature is below 40°F., the outdoor thermostat will shut down heat pump operation.

1. Turn the selector switch to “HEAT PUMP”;

2. The Fan and Compressor will come on and begin heating.

3. When desired temperature level in RV is reached, the blower will run continuously to circulate air and maintain an even temperature. The compressor will cycle as required to maintain selected temperature.

Off Position

This position turns the unit off.

B2a. Mechanical Controls

This type of heat pump has an air distribution box that has a mechanical selector switch and thermostat installed in it.

Note: Remember to check the installation and operating instructions for the specific model you are diagnosing.

Controls

The Selector Switch has eight positions including “OFF”. This controls fan speed, heating mode and cooling modes.

The Thermostat controls the temperature range from 65°F. on the coldest side to 90°F. on the warmest side. In the cooling/heating mode, the compressor ON/OFF is controlled by the thermostat setting.

Cooling Operation

Set the thermostat at the desired temperature level. Select the fan speed that best satisfies your needs: a. HIGH COOL: Selected when maximum cooling and

dehumidification is required.

b. LOW COOL: Selected when room is at desired com-

fort level and needs to be maintained. Normally this

speed is used for nighttime operation. Note: The blower runs continuously to circulate air and maintain an even temperature. The compressor will come on when cooling is required to maintain the selected temperature level.

After shutting the heat pump down with either selector switch or thermostat, wait at least two (2) minutes before restarting. This allows the refrigerant pressure to equalize and compressor to restart easily.

B2b. Bimetal Relay Controls

Note: Remember to check the installation and operating instructions for the specific model of air conditioner you are diagnosing.

Bimetal Cooling Operation

Place the Temperature Set Lever (1) to desired temperature level (located at top of thermostat). Select fan speed that best satisfies your needs: (upper right switch at bottom of thermostat) (4). a. High Speed: Selected when maximum cooling and

dehumidification are required.

b. Low Speed: Selected when RV reaches desired com-

fort level and needs to be maintained. Normally this

speed is used for nighttime operation. Select Auto/ON Switch (2) operation as follows: (Lower right switch at bottom of thermostat) a. Auto Position: Air conditioner fan runs whenever cool-

ing is required and stops whenever cooling is not re-

quired. b. On Position: Air conditioner fan runs continuously to

circulate air in RV. Set the system switch to cool position. (Located at lower left side of thermostat)

The air conditioner will now come on when cooling is required and cycle off when the temperature level selected is reached.

B2. Heat Pump

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Section B - Operation, cont’d.

FIG. B18

B2c. Analog Control System

FIG. B19

SYSTEM

COOL

OFF

FURNACE

HEAT PUMP

COOL

FURNACE

HEAT PUMP

HEAT STRIP

Wait at least two (2) minutes before restarting the air conditioner after shutting off with either the Heat/Off/Cooling Switch or the Temperature Set Lever. This allows the refrigerant pressure in the air conditioner to equalize and will allow the compressor to restart easily.

Heating Operation (If furnace is connected to thermostat)

Set Temperature Set Lever (1) to desired temperature level (located at top of thermostat). Set the System Switch to heat position (located at lower left side of thermostat(.

The furnace will now come on then heat is required and cycle off when temperature level selected is reached.

Special Feature

When thermostat System Switch is in the OFF or HEAT position and Auto/On Switch is in the ON position, the air conditioner fan will run continuously to circulate the air inside the RV.

Heat Pump Operation - See FIG. B18

1. Set the Temperature Set Lever (1) to desired temperature setting.

2. Set the System Switch (3) to heat pump position.

3. Move the FAN Auto/On Switch (2): a. Auto Position: Unit fan runs whenever heat is re-

quired and stops whenever heating is not required.

b. ON Position: Unit fan runs continuously to circu-

late air in RV.

4. Select the desired fan speed by moving the fan speed switch (4) to : a. High speed: Selected for maximum air flow. The

discharge air will feel cool.

b. Low speed: Selected normally for heat pump op-

eration. The lower air flow allows it to feel warmer.

1. Temperature Set Lever

2. Fan Auto/On Switch

3. System Switch

4. Fan High/Low Switch

Analog Control Cooling Operation - See FIG. B19

1. Place the Temperature Set Lever (1) to desired temperature level.

2. Select desired fan speed by moving the Fan Speed Switch (4) to: a. High Speed: Selected when maximum cooling and

dehumidification are required.

b. Low Speed: Selected when RV reaches desired

comfort level and needs to be maintained. Normally this speed is used for night time operation.

3. Move the FAN Auto/On Switch (2): a. Auto Position: Unit fan runs whenever cooling is

required and stops whenever cooling is not required.

b. ON Position: Unit fan runs continuously to circu-

late air in RV.

4. Set the System Switch to cool position. The unit compressor will now come ON and cycle OFF when the temperature level selected is reached.

Furnace Operation (If furnace is connected to relay box.) - See FIG. B19

1. Set the Temperature Set Lever (1) to desired temperature setting.

2. Set the System Switch (3) to furnace position. The furnace will now come ON when heat is required and cycle OFF when the temperature setting selected is reached.

FAN

AUTO

SYSTEM

OFF

HEAT PUMP

SYSTEM

COOL

OFF

FURNACE

AUTO

FAN

10 °C

AUTO

FAN

10 °C

Section B - Operation, cont’d.

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B2. Heat Pump

Analog Control Electric Heat Pump Operation - See FIG. B19

1. Set the Temperature Set Lever (1) to desired temperature level.

2. Set the System Switch (3) to heat pump position.

3. Move the a. Auto Position: Unit fan runs whenever heat is re-

b. ON Position: Unit fan runs continuously to circu-

4. Select desired fan speed by moving the Fan Speed Switch (4) to: a. High Speed: Selected when maximum air flow is

b. Low Speed: Normally selected for heat pump op-

Continuous Blower Operation

1. Set the System Switch (3) to any position (including “OFF”).

2. Move the FAN Auto/On Switch (2) to the ON position, the unit fan will operate continuously at the fan speed selected by the Fan Speed Switch (4).

3. Select desired fan speed by moving the Fan Speed Switch (4) to: a. High Speed: Selected when maximum air flow is

b. Low Speed: Normally selected for heat pump op-

FAN Auto/On Switch (2):

quired and stops whenever heating is not required.

late air in RV.

required. The discharge air will feel cool due to the maximum air flow. It is normally not used for heat pump operation.

eration, because less air movement is needed for heat and discharge air is warmer.

required. The discharge air will feel cool due to the maximum air flow. It is normally not used for heat pump operation.

eration, because less air movement is needed for heat and discharge air is warmer.

B2d. Comfort Control Center

The Comfort Control Center has been designed for you to easily operate all the air conditioning and gas heating appliances found in your vehicle from one location.

In order to familiarize yourself with the operation of the Comfort Control Center, see Section B1d on page 16.

Make sure that the power supply to the unit is disconnected before performing any work on the unit to avoid the possibility of shock injury or damage to the equipment.

Section C - Components

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C1. Motors

Roof Top Units - To check the motor, turn the unit circuit

breaker to OFF. With an AC volt meter, verify that the circuit has no AC volts. On most units, the wires from the motor connect directly into a 6 or 9 pin connector. The motor leads are white (common), black (high), red (low) and yellow (medium). Some units are 2-speed. If you are checking a 2 speed system, disregard the yellow wire. Set your VOM to the ohms scale. You will perform a continuity test. Check for continuity between the white wire and each of the other wires.

Lack of continuity between the white wire and any of the other wires indicates an open circuit and requires that the motor be changed. Next, check for continuity between each wire and the green/yellow wire. If you get continuity, you have a grounded motor and it must be replaced.

On Models 620315 and 630215, the motor leads do not go

FIG. C1

into a connector. On these units, disconnect the wires from the AC power module and do the previous tests between the motor leads.

Single Compressor Units

The units that have a single compressor are Models:

39015.XXX

39025.XXX

39035.XXX

39045.XXX

39115.XXX

39325.XXX

39335.XXX

To check the motor, turn the unit circuit breaker OFF. With an AC voltmeter, verify that the circuit has no AC voltage. Next, locate the electric box and remove its cover. The motor leads will connect to a relay or a power module board and the run capacitor. Disconnect the motor leads.

Set your ohm meter to its highest scale for these tests. Check for continuity between the white wire and each of the other wire. Lack of continuity between the white wire and any of the other wires indicates an open circuit and requires that the motor be changed. Next, scrape some paint off the motor casing and check for continuity between each wire and unit casing or the motor casing. If you get continuity between each wire and unit casing or the motor casing. If you get continuity between any of the wires and the motor casing, you have a grounded motor and it must be replaced.

There are two types of motors used on these models. One is a single-speed motor and the other is a two-speed motor (high and low). The single speed motor has three wires: White (common), Black (high) and Brown (capacitor). The two-speed has four wires: White (common), Black (high), Red (low) and Brown (capacitor).

Dual Compressor Units

The units that have dual compressors are Models:

39224.601 and 39424.601 To check the motor, turn the unit circuit breaker or breakers OFF. With an AC volt meter, verify that the circuit has no AC voltage. The wires from the motor connect to a 9-pin connector. The motor leads are white (common - Terminal

4), black (high - Terminal 6) and red (low - Terminal 7). Set your ohm meter to its highest scale for these tests. Check for continuity between the white wire and each of the other wires.

FIG. C3

FIG. C2

Section C - Components, cont’d.

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FIG. C4

Another test is the motor amperage on high speed. The amp meter is clamped around the black (high speed) lead. The high speed running amps of the motor should be ±1/ 10 of rating plate motor amps. If amp reading is above normal (listed on rating plate), the fan capacitor may be defective. Verify that the fan run capacitor is of the correct rating for the motor. See Section C2.

C2. Capacitor, Fan/Run

The run capacitor may be one of two different kings: Either a single capacitor for the fan or compressor, or a combination capacitor for both the fan and the compressor.

The run capacitor should be checked with a capacitor tester. Follow the tester manufacturer’s testing procedures. If one is not available, an ohm meter may be used. Turn the air conditioner circuit breaker OFF. See FIG. C5.

FIG. C5

the VOM meter to the highest ohm scale and connect the probes to the capacitor terminals. The reading should rapidly move toward continuity and slowly return to infinity. You should reverse the leads and repeat the procedure. If there is no reading, or a prolonged reading, replace the run capacitor. The combination run capacitor has three terminals. The terminals are marked “F”, “C” and “HERM”. To check the combination run capacitor, follow the discharge procedures above. Again, make sure you test from “C” (common) to “F” (fan) and “C” (common) to “HERM” (compressor).

C3. Start Capacitor

The unit will have one of two types of start capacitor. One type has a 15,000 ohm resistor between the terminals. The other type does not have the resistor.

There may be a charge on the capacitor until discharged.

Using an AC voltmeter set at the 500 volt scale or higher, connect the meter leads to the terminals of the capacitor.

Start Capacitor with Resistor

The start capacitor should be checked with a capacitor tester. Follow the tester manufacturer’s testing procedures. If one is not available, an ohm meter may be used. Turn the unit’s circuit breaker OFF. Disconnect the wires to the capacitor. The start capacitor does not need to be manually discharged since it has a built-in resistor. Use only an analog or dial-type ohm meter. Set the ohm meter to the highest ohm scale and connect the probes to the capacitor terminals. The reading should show continuity and slowly return to 15,000 ohms. You should then reverse the leads and check again. If there is not reading or a reading greater than 15,000 ohms, the start capacitor should be replaced. See FIG. C6.

Start Capacitor without Resistor

FIG. C6

The start capacitor (without resistor) must be manually discharged in the same way the run capacitor was done a

There may be a charge on the capacitor until discharged.

The run capacitor must be manually discharged. Using an AC voltmeter set at the 500 volt scale or higher, connect meter leads to the terminals of the capacitor. After discharging the capacitor, disconnect the wires to the capacitor. Set

moment ago. See Section C2. Check this style capacitor the same way you would check the capacitor with the resistor. The reading will be different. The reading should show continuity and slowly return to infinity. Reverse the leads and check again. If there is no reading or a reading of “0” ohms, the start capacitor should be replaced. See FIG. C7.

FIG. C7

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User Manual