Part 2 of 2

Chart C-10:

A/C Circuit:

CIRCUIT DESCRIPTION:
The A/C compressor clutch control relay is energized when the ECM provides a ground path through CKT 366 and A/C is requested. A/C compressor clutch is delayed about .3 second after A/C is requested. This will allow the IAC to adjust engine RPM for the additional load.

The A/C compressor clutch control relay will remain disengaged if refrigerant pressure is out of range described previously in this section, or there is no A/C request signal due to an open A/C select switch or circuit.

TEST DESCRIPTION: Number(s) below refer to circled number(s) on the diagnostic chart.
1. Determines if the A/C refrigerant pressure sensor 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 CKT 366, which should cause the test light to be "ON."

DIAGNOSTIC AIDS:
If complaint is insufficient cooling, the problem may be caused by an inoperative cooling fan. See Chart C-12, Coolant Fan Control Circuit. If fan operates correctly, refer to Heating and Air Conditioning. A/C refrigerant pressure outside of a range of 38 to 429 psi will cause the compressor to be disabled by the ECM. With a scan tool, observe A/C refrigerant pressure for 2 minutes with engine idling and A/C "ON." If refrigerant pressure goes out of range, refer to Heating and Air Conditioning to measure and diagnose. Scan pressure should he within 20 psi of actual. If not, check for a circuit problem using DTC 66 chart or replace A/C refrigerant pressure sensor.