Dodge Durango

 Service Manual

Heating and Air Conditioning » Description and operation
Electronic cycling clutch switch

DESCRIPTION

The Electronic Cycling Clutch Switch (ECCS) is mounted to the outboard side of the thermal expansion valve in the engine compartment. A thermistor probe within a capillary tube on the switch is inserted into a well on the side of the expansion valve filled with a thermally-conductive grease. This arrangement allows the ECCS to monitor the temperature of the expanded refrigerant entering the evaporator.

OPERATION

The function of the ECCS is to prevent refrigerant temperatures from becoming so low that condensation freezes on the evaporator fins. This condition is referred to as evaporator icing. Evaporator icing reduces air conditioning system air flow and cooling performance.

The ECCS is connected in series electrically with the heater-A/C mode control switch, the low pressure cut-off switch and the high pressure cut-off switch between ground and the Powertrain Control Module (PCM). The ECCS will open when it monitors a refrigerant temperature below about 2.9 C (37.2 F), and will close again when the refrigerant temperature reaches about 4.3 C (39.7 F). The opening and closing of the ECCS signals the PCM to cycle the compressor clutch on and off through the compressor clutch relay.

The ECCS is a factory sealed and calibrated unit and cannot be adjusted or repaired. If faulty or damaged, the ECCS must be replaced.

Blower motor

Blower motor relay

Blower motor resistor

Blower motor switch

Compressor

Compressor clutch

Compressor clutch relay

Condenser

Electronic cycling clutch switch

Evaporator coil

Expansion valve

Filter-drier

Heater and air conditioner

Heater and air conditioner control

Heater core

High pressure cut-off switch

High pressure relief valve

Low pressure cut-off switch

Rear overhead air conditioner

Refrigerant

Refrigerant lines

Refrigerant line couplers

Refrigerant oil

Refrigerant system service ports

Vacuum check valve

Vacuum reservoir