A/C Compressor Clutch Electrical Circuit Check

OPERATION PROCEDURE

1. The proper operation of the A/C compressor clutch is essential for uninterrupted operation of the air conditioning system.
2. Warm up the engine to normal operating temperature, set the A/C controls to maximum cooling and turn the blower fan to maximum speed. To prevent automatic shutdown of the system, open all cabin doors.
3. Ask an assistant to press the A/C button and observe the front of the compressor. The clutch should make a clearly audible click, after which its center section starts to rotate. If this does not happen, switch off the engine and disconnect the wiring from the A/C pressure switch. Jumper the terminals of the wiring harness connector using a paper clip. If the clutch now operates normally, this indicates excessive pressure rise or drop in the system. Take the vehicle to a specialized repair shop for further diagnosis.
4. If the compressor clutch still does not engage as required, check the condition of the relevant fuses: remove fuse No. 3 from the junction block located on the left under the instrument panel, and fuse No. 58 from the main junction block located in the engine compartment (on the rear bulkhead).
5. Also remove the compressor clutch relay (junction block in the engine compartment) and check its operation (see Chapter Electrical Equipment). With the relay removed and the ignition off, verify battery voltage at relay socket 1 (the terminal layout is the same as for the fan relay). With the ignition on, battery voltage should be present at socket 4.
6. With the engine running and the A/C on, use jumper wires to connect sockets 1 and 2 of the relay to the compressor clutch relay. The clutch should click clearly at the moment of connection.
7. If the clutch still does not engage, switch off the ignition again, disconnect the wiring from the clutch, and use a long jumper wire and an ohmmeter to verify continuity between terminal 2 on the compressor clutch relay plug and the compressor clutch connector socket. If there is no continuity, check the circuit for an open between the junction block and the clutch connector. If continuity is present, verify that there is no open circuit between the junction block and the PCM.