Throttle Full Open Switch: Description and Operation

PURPOSE
The Wide Open Throttle A/C Cut-off (WAC) output is used by the PCM to control A/C clutch operation.

OPERATION
When A/C is requested to the PCM through the A/C Cycling Switch (ACCS) input, the Powertrain Control Module (PCM) verifies that A/C clutch operation is desirable (engine not cranking or overheating, not at Wide Open Throttle [WOT]). If A/C clutch operation is desirable, the PCM adjusts idle speed as necessary and "ungrounds" the WAC output, which signals to the Constant Control Relay Module (CCRM) that the A/C clutch may be activated. The CCRM then supplies voltage to the Power-to-A/C Clutch circuit, activating the A/C clutch. During A/C operation, if the PCM determines that A/C clutch operation is not desirable, the WAC output is turned ON (grounded) and the CCRM turns OFF the A/C clutch. Under normal conditions with the A/C OFF, the PCM grounds the WAC output. The Wide Open Throttle A/C Cut-Off relay functions as a normally closed relay.