Durango 4WD V8-5.9L VIN Z (1998)
Low Pressure Sensor / Switch: Description and Operation
Electronic Cycling Clutch Switch
Electronic Cycling Clutch Switch
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.
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.
