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 terminals of the connector illustrated in the first image.

Test A Isolation Test Part 1 Of 2:

^ If tests are good, proceed to step 2.
^ If the test lamp does not light at terminal A, check PPL wire (901) and PNK wire (639). Idle Speed Power Steering 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 wire (67) 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 second image. Note Compressor Clutch action.

Test A Isolation Test Part 2 Of 2:

^ 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