Duo-Therm DIAGNOSTIC SERVICE MANUAL Comfort Control …

1 1 DIAGNOSTIC SERVICE MANUALDuo-Therm Comfort Control Center SystemsSYMPTOM CAUSE REFER TO STEPThis program will address the most common system problems associated with the Duo-Therm Comfort ControlCenter supplied by The Dometic Corporation. Our intent is to provide you with a guideline of checks to make,should you encounter one of the following Control CENTER SECTION:1. Turn to "ON" No Turn to "ON" Has display, improper Multiple Units: One unit operates and improperoperation on other unit(s).

2 ROOF MOUNTED AIR CONDITIONER SECTION:1. Unit does not run: No fan, no Fan operates: Compressor will not come on (doesnot "hum")3. Fan Operates: Compressor tries to start, cycles"OFF" and "Hums" again, or blows circuit 1 MDC Volts 4 Cable Assembly Power Module Board Control Center 1 Reset 1 MConfiguration 2 Wiring Power Module Board Control Center

3 1 Reset 1 MConfiguration 2 Wiring Power Module Board Control Center 2 Operation 1AC Voltage Voltage 4 Breaker Assembly Control Center Power Module Board 1 Cable Assembly Control Power Module Board AComfort Control Center Voltage or Run Capacitor & ControlOverload Protector ,A2,A3B1.

4 B2,B3,B7,B8,C,DDiagnostic SERVICE Manuals2 Duo-Therm Comfort Control Center SystemsDIAGNOSTIC SERVICE MANUALSYMPTOMCAUSEREFER TO STEP(Roof Mounted Air Conditioner Sec. continued) operates: compressor runs for a short while,cycles "OFF", cycles back "ON". runs, no runs, but not on all distribution box unit: Evaporator in ceiling unit: Evaporator distribution box unit: Insufficient cooling,compressor runs Duct in ceiling unit: Insufficient cooling, compressorruns Flow Distribution Power Module Control Power Module Control Flow Tube Flow Distribution Tube Flow Gain/Heat Flow Distribution Gain/Heat SERVICE MANUALDuo-Therm Comfort Control Center SystemsSYMPTOMCAUSEREFER TO STEP(Roof Mounted Air Conditioner Sec.)

5 Continued)11. Air distribution box unit: Insufficient cooling withreduced air Duct in ceiling unit: Insufficient cooling with reducedair Excessive Noisy MOUNTED HEAT PUMP does not run: No fan, no operates: Compressor will not come on (doesnot "hum". operates: Compressor tries to start, cycles"OFF" and "hums" again, or blows circuit operates; compressor runs for a short time,cycles "OFF", cycles back "ON".Air Flow flow Distribution Power Module Control Blades Control Power Module Power Module Control or Run & Flow Distribution ,B3,B4,B8C,D4 Duo-Therm Comfort Control Center SystemsDIAGNOSTIC SERVICE MANUALSYMPTOMCAUSEREFER TO STEP(Roof Mounted Heat Pump Sec.)

6 Continued) runs, no runs, but not on all distribution box unit: Inside coil in ceiling unit: Inside coil Distribution Box Unit: Insufficient cooling orheating, compressor runs Duct in ceiling unit: Insufficient cooling or heating,compressor runs Air distribution box unit: Insufficient cooling orheating with reduced air Duct in ceiling unit: Insufficient cooling or heatingwith reduced air Excessive cooling or Power Module Control Power Module Control Flow Tube Flow Distribution Tube Flow Gain/Heat Flow Distribution Gain/Heat Flow Flow Distribution Power Control SERVICE MANUALDuo-Therm Comfort Control Center SystemsSYMPTOMCAUSEREFER TO STEP(Roof Mounted Heat Pump Sec.

7 Continued)14. Unit operation in wrong mode (cool instead of heatpump or reversed)15. Noisy OperationBASEMENT (SINGLE COMPRESSOR)AIR CONDITIONER SECTION:1. Unit does not run; no fan, no Fan operates; compressor will not come on (does not"hum")3. Fan operates; compressor tries to start, cycles "OFF"and "hum" again, or blows circuit Fan operates; compressor runs for a short time, cycles"OFF", cycles back "ON".Operation1 Ambient Control Blades Control Power Module Power Module Control or Run & Flow Distribution ,B5,C,D6 Duo-Therm Comfort Control Center SystemsDIAGNOSTIC SERVICE MANUALSYMPTOMCAUSEREFER TO STEP(Basement [Single Compressor] A/C )5.

8 Compressor runs, no Fan runs, but not on all Evaporator Insufficient cooling, compressor runs Insufficient cooling with reduced air Excessive Noisy (SINGLE COMPRESSOR)HEAT PUMP SECTION:1. Unit does not run; no fan, no Power Module Control Power Module Control Flow Tube Flow Distribution Gain/Heat Flow Distribution Power Module Control Blades A6,B6,C,DOperation1AC Control Power Module SERVICE MANUALDuo-Therm Comfort Control Center SystemsSYMPTOMCAUSEREFER TO STEP(Basement [Single Compressor] H/P )2.

9 Fan operates; compressor will not come on (does not"hum")3. Fan operates; compressor tries to start, cycles "OFF"and "hums" again, or blows circuit Fan operates; compressor runs for a short while,cycles "OFF", cycles back "ON".5. Compressor runs; no Fan runs; but not on all Inside coil Insufficient cooling or heating; compressor runs Power Module Control or Run & Flow Distribution Power Module Control Power Module Control Flow Distribution Tube Flow Distribution Gain/Heat Comfort Control Center SystemsDIAGNOSTIC SERVICE MANUALSYMPTOMCAUSEREFER TO STEP(Basement [Single Compressor] H/P )9.

10 Insufficient cooling or heating with reduced air Excessive cooling or Unit operates in wrong mode (cool instead of heatpump or reversed)12. Noisy (DUAL COMPRESSOR)AIR CONDITIONER SECTION:1. Unit does not run; no fan, no Fan operates; compressor will not come "ON" (doesnot "hum")3. Fan operates; compressor tries to start, cycles "OFF"and "hums" again, or blows circuit Flow Distribution Power Module Control Control Blades Control Power Module Power Module Control or Run & SERVICE MANUALDuo-Therm Comfort Control Center SystemsSYMPTOMCAUSEREFER TO STEP(Basement [Dual Compressor] A/C )4.