Part 1 of 2

Chart C-10 (Part 1 Of 2):

Wiring Diagram (A/C Clutch Control Circuit):

CIRCUIT DESCRIPTION:

The A/C clutch control relay is energized when the ECM provides a ground path through CKT 459 and A/C is requested. A/C clutch is delayed about 0.3 seconds after A/C is requested. This will allow the IAC to adjust engine rpm for the additional load.

The ECM will temporarily disengage the A/C clutch relay for calibrated times for one or more of the following:

^ Hot engine restart.
^ Wide open throttle (TPS over 90%).
^ Power steering pressure high (open power steering pressure switch).
^ Engine rpm greater than about 6000 rpm.
^ During IAC reset.

The A/C clutch relay will remain disengaged when a Code 66 is present, if pressure is out of range or there is no A/C request signal due to an open A/C select switch or circuit.


TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.

1. The ECM will only energize the A/C relay when the engine is running. This test will determine if the relay or CKT 459 is faulty.

2. Determines if the signal is reaching the ECM through CKT 66 from the A/C control panel. Signal should only be present when an A/C mode or defrost mode has been selected.

3. If the ECM is receiving a high power steering pressure signal, the A/C clutch will be disengaged by the ECM.