Part 2 of 2

Chart C-10 (Part 2 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. Determines if the pressure transducer is out of range causing the compressor clutch to be disengaged.

2. With the engine stopped and Field Service Mode activated, the ECM should be grounding circuit 459, which should cause the test light to be "ON".



DIAGNOSTIC AIDS:

If complaint is insufficient cooling, the problem may be caused by a inoperative cooling fan. See CHART C-12 for cooling fan diagnosis. If fan operates correctly it may be an A/C problem see HEATING VENTILATION AND AIR CONDITIONING. A/C pressure outside of a range of 43 to 428 psi will cause the compressor to be disabled by the ECM. Observe "Scan" A/C pressure for 2 minutes with engine idling and A/C "ON." Scan pressure should be within 20 psi of actual reading on manifold gages. If not check for circuit problem using Code 66 chart or replace sensor.