Component Diagnostic Charts/Tests

Chart C-10 - A/C Clutch Control (Part 1 of 2):

Wiring Diagram for Chart C-10 - A/C Clutch Control:

CHART C-10 - A/C CLUTCH CONTROL (PART 1 OF 2)

Circuit Description:


The A/C clutch control relay is ECM controlled to delay A/C clutch engagement .4 seconds after A/C is turned "ON." This allows the IAC to adjust engine rpm before the A/C clutch engages. The ECM also causes the relay to disengage the A/C clutch during WOT operation. The A/C clutch control relay is energized when the ECM provides a ground path for CKT 959.


Test Description: Numbers below refer to circled numbers on the diagnostic chart.

1. Checks to see if ECM is controlling A/C clutch control relay.

2. Checks operation of A/C cycling switch.


3. Checks for grounded CKT 959 to ECM. At this point the test light should be "OFF."

4. Checks for open circuit on either side of relay coil.

Chart C-10 - A/C Clutch Control (Part 2 of 2):

CHART C-10 - A/C CLUTCH CONTROL (PART 2 OF 2) CONTINUED FROM CHART C-10

Test Description: Numbers below refer to circled numbers on the diagnostic chart.

5. Check for battery voltage to relay through CKT 67. Substitutes for relay to determine if problem is in relay or in CKT 59, A/C clutch coil, high pressure switch or ground.


6. Checks for open in CKT 67 between cycling switch and A/C fuse, or open CKT 67 to relay.

7. Check to see that A/C "ON" is getting to ECM through CKT 67. A test OFF" at this time indicates CKT 67 is open between the cycling switch and the ECM.