Refrigerant Pressure Sensor / Switch: Testing and Inspection

Fig. 27 H-valve assembly. Typical:

The cycling clutch switch is wired in series with the compressor clutch coil and is secured to the suction line next to the H valve assembly. The CC switch utilizes a capillary tube to monitor the temperature of the suction line and turns the compressor on and off as necessary. The switch is calibrated and sealed. If defective, it must be replaced. To test the CC switch proceed as follows:
1. Disconnect electrical connector from cycling clutch switch.
2. Check continuity of switch. Contacts should be closed at temperatures above 45°F. If not, replace switch.
3. If contacts are closed, check switch operation as follows:
a. Connect electrical connector to cycling clutch switch.
b. Set temperature control lever to full cool position.
c. Set A/C blower motor to LOW and push A/C button.
d. Run engine at 1300 RPM for about 5 minutes to stabilize A/C system.
e. If compressor clutch cycles on and off 2 or more times a minute with a temperature between 68 and 90 °F switch is normal. If clutch fails to engage, check for open in electrical circuit. Compressor clutch may be continually engaged above the higher temperature parameter due to heat load. This condition is normal and should not be cause for concern.