Part 1 of 2

Chart C-10B Part 1 Of 2:

A/C Clutch Wiring Diagram:

CIRCUIT DESCRIPTION:


The A/C clutch control relay is ECM controlled to delay A/C clutch engagement about O.4 second 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, when high power steering pressure is present, or if engine is overheating.

The A/C clutch control relay is energized, when the ECM provides a ground path for CKT 459. The A/C pressure sensor is used to determine high and low pressure in the system and also turns "ON" the coolant fan when needed.

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 circuit 66 from the A/C control panel. Signal should only be present when the A/C mode or defrost mode has been selected.

3. If the ECM is seeing a high power steering pressure signal, the A/C clutch will disengage by the ECM.


DIAGNOSTIC AIDS:

If complaint was insufficient cooling, the problem may be caused by a inoperative cooling fan, or A/C pressure fan switch. The engine cooling fan should turn "ON," when A/C pressure exceeds a value to open the switch, which causes the ECM to energize the cooling fan relay. See CHART C-12 for cooling fan diagnosis. If fan operates correctly, see HEATING VENTILATION AND AIR CONDITIONING.