Part 2 of 2

Chart C-10 - Part 2 Of 2:

A/C Pressure Sensors:

CIRCUIT DESCRIPTION
The A/C compressor clutch control relay is energized when the PCM provides a ground path through CKT 459 when A/C is requested. A/C compressor clutch is delayed about .3 seconds after A/C is requested. This will allow the IAC valve to adjust engine RPM for the additional load.

The A/C compressor clutch control relay will remain disengaged 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 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 A/C relay output test activated, the PCM should be grounding CKT 459, which should cause the test light to be "ON."

DIAGNOSTIC AIDS:
If complaint is insufficient cooling, the problem may be caused by an inoperative engine cooling fan(s). Refer to CHART C-12 for cooling fans diagnosis. [1][2]Chart C-12 Coolant Fan Control Circuit
A/C pressure outside of a range of 38 to 429 psi will cause the compressor to be disabled by the PCM. Observe Tech 1 A/C pressure for 2 minutes with engine idling and A/C "ON." Tech 1 pressure should be within 20 psi of actual. If not, check for a circuit problem using Diagnostic Trouble Code (DTC) 66 or 70.
If checks are OK, replace A/C refrigerant pressure sensor.