Part 2 of 2

Chart C-10 Part 2 Of 2:

A/C Refrigerant Pressure Sensor & Compressor Wiring Schematic:

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 0.3 seconds after A/C is requested. This will allow the Idle Air Control (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 described previously in this section, or there is no A/C request signal due to an open A/C select switch or circuit.

CHART 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 Powertrain Control Module (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. Chart C-12 Coolant Fan Control Circuit
If fans operate correctly, refer to Heating and Air Conditioning. A/C pressure outside of a range of -17 to 457 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." If pressure goes out of range, measure pressures and diagnose. Tech 1 pressure should be within 20 psi of actual. If not, check for a circuit problem using Diagnostic Trouble Code (DTC) P1530 chart. P1530
If checkout is OK, replace A/C refrigerant pressure sensor.