Ä |
|
HEATING AND AIR CONDITIONING 24 - 15 |
|
FIN-SENSING CYCLING CLUTCH SWITCH TESTS
At temperatures above 32°C (90°F) the compressor clutch may engage continuously and not cycle. This is due to evaporator temperature above the freezing point.
The work area and vehicle must be between 21°C (70°F) and 32°C (90°F) when testing the Fin-sensing Cycling Switch.
(1) Disconnect the 3-wire connector from switch lead located behind the glove box.
(2) Test for voltage between pin #1 to pin #3 on the wire harness connector (Fig. 6). If voltage is not detected, refer to the Front Wheel Drive Car-Wiring Diagrams Service Manual. If voltage is detected, jump pin #1 to pin #3 using a jumper wire. Compressor clutch should engage.
Fig. 4 Thermal Limiter Switch
To replace switch, refer to Thermal Limiter Switch.
FIN-SENSING CYCLING CLUTCH SWITCH DIAGNOSIS
The Fin-Sensing Cycling Clutch Switch (FCCS) (Fig. 5) is located in the heater-A/C unit housing near the blower motor and placed in the evaporator fins. The FCCS prevents evaporator condensate freeze-up. This is done by cycling the compressor clutch OFF when evaporator temperature drops below freeze point. It cycles ON when the evaporator temperature rises above freeze point. The FCCS uses a thermistor probe in a capillary tube inserted between the evaporator fins in the heater-A/C unit housing. If the compressor clutch does not cycle, and all other clutch circuit components test correct, test the switch. Refer to Fin-Sensing Cycling Clutch Switch Tests.
Fig. 5 Fin-sensing Cycling Clutch Switch
Fig. 6 Fin-sensing Cycling Clutch Switch Harness
Connector
(3) If compressor clutch engages, test for continuity from terminal pin #1 to pin #3 of the switch lead connector. Continuity should be detected. If not, replace the Fin-sensing Cycling Clutch Switch.
FIXED DISPLACEMENT COMPRESSOR REFRIGERANT SYSTEM
Refer to the Refrigerant System Diagnosis chart in this section.
SILVER EXPANSION VALVE TEST
Expansion valve tests should be performed after compressor tests.
Review Safety Precautions and Warnings in the General Information section of this Group. The work area and vehicle must be 21°C to 27°C (70°F to 85°F) when testing expansion valve. To test the expansion valve:
(1)Connect a charging station or manifold gauge set to the refrigerant system service ports. Verify the refrigerant charge level using the sight glass method.
(2)Disconnect and plug the vacuum line at the water control valve.
24 - 16 HEATING AND AIR CONDITIONING |
|
Ä |
|