KM - Testing Notes

NOTE: You should enter this Pinpoint Test only when directed here from Diagnostic Routines or Pinpoint Test TA.

REMEMBER: To prevent the replacement of good components, be aware that the following non-Electronic Engine Controls (EEC) areas may be at fault:

- Refrigerant charge

- Ambient temperature less than 7°C (45°F)

This Pinpoint Test is intended to diagnose only the following:

- Harness circuits: Wide Open Throttle A/C Cut-Off (WAC), VPWR, GND, POWER-TO-CLUTCH, AC Demand (ACD)

- WAC relay (11433 or 13A025)

- Powertrain Control Module (PCM) (12A650)

DESCRIPTION:

The WAC output (Pin 54) is used by the Powertrain Control Module to disengage the A/C clutch when compressor operation is not desirable. Under normal conditions, with the A/C off, the PCM will ground the WAC output, which opens the normally closed WAC relay. When the A/C demand switch is turned on, and the cyclic pressure switch/low pressure switch is closed, voltage is supplied to the WAC relay contacts and to the AC Clutch Supply (ACCS) circuit (Pin 10). The voltage on the ACC/S circuit indicates to the PCM that A/C is requested. The PCM will then verify that A/C clutch operation is desirable (ex. engine not cranking or overheated, not at Wide Open Throttle (WOT), etc.) If A/C clutch operation is desirable, the PCM will adjust idle speed as necessary and "unground" the WAC output, which closes the normally closed WAC relay and allows voltage to be supplied to the A/C clutch.