Test A: Isolation Test

1. Remove the connector from the A/C Compressor Control Relay and check the voltage to ground using a test lamp at the following terminals of the connector:

Test A Isolation Test:

^ If tests are good, proceed to step 2.
^ If the Test Lamp does not light at Terminal A check LT BLU/ORN (495) wire and PNK (639) wire Idle Speed Power Steering Pressure Switch should be closed.
^ If the Test Lamp does not light at Terminal B, jumper the Pressure Cycling Switch harness connector.

- If Test Lamp now lights at Terminal B of the A/C Compressor Control Relay, check refrigerant charge. If refrigerant charge is good, replace the Pressure Cycling Switch.
- Check LT BLU (67) wire for an open.
- If Pressure Cycling Switch is closed and LT BLU (67) wire is good, proceed to Test D. Test D: A/C Control Assembly Output Test.

2. With the connector removed from the A/C Compressor Control Relay, connect a fused jumper between the terminals given in the following table. Note Compressor Clutch action.

Isolation Test:

^ If the A/C Compressor Clutch engages (loud click), the clutch and A/C Control Assembly circuits are good. Proceed to Test C. Test C: ECM Compressor Control Test.
^ If the A/C Compressor Clutch does not engage proceed to Test B. Test B: A/C Compressor Clutch Test.