Part 1 of 2

Chart C-10 Part 1 Of 2:

Wiring Diagram:

CIRCUIT DESCRIPTION:

The A/C clutch control relay is ECM controlled to delay A/C clutch engagement 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 whenever the following conditions exist:

^ WOT operation.
^ High coolant temperature.
^ High engine oil temperature.
^ High engine speed.


The ECM can determine A/C request by sending a voltage signal to the A/C control head. When the A/C control switch is closed, the A/C request voltage signal is grounded. This is shown on the scan tool as A/C showing a request.
When a request for A/C has been detected by the ECM, the ECM will ground the A/C clutch control relay drive circuit, the relay contacts will close and energize the compressor clutch portion of the circuit. If the system is properly charged, the circuit will be complete to the A/C compressor clutch.
When A/C request has been detected by the ECM, the cooling fan(s) will be turned "ON" unless vehicle speed is too high.


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

1. Refer to wiring diagrams for fuse circuit power distribution.

2. Checks to see if the ECM can control the A/C clutch control relay.

3. Checks to determine if the ECM is capable of detecting the A/C request signal being grounded.

4. Indicates possible problems with the A/C control components. The C68 control system incorporates a solid state automatic air conditioning system.