Component Diagnostic Charts/Tests
Chart C-10 - A/C Clutch Control:
Wiring Diagram for Chart C-10 - A/C Clutch Control:
CHART C-10 - A/C CLUTCH CONTROL
Circuit Description:
ECM control of the A/C clutch improves idle quality and performance by
^ delaying clutch apply until the idle air rate is increased
^ releasing clutch when idle speed is too low
^ releasing clutch at wide open throttle
^ smooths cycling of the compressor by providing additional fuel at the instant clutch is applied.
Voltage is supplied to the A/C clutch control relay on CKT 50 when the A/C power relay is energized by the A/C control switch. Also, when the A/C is turned "ON," voltage is supplied to the A/C relay coil on CKT 67 through the closed pressure cycling switch. This same voltage is supplied as a signal to ECM pin B8. After a time delay of about 1/2 second the ECM will ground terminal "C2", CKT 458, and close the A/C relay.
When relay is energized battery voltage from CKT 50 is supplied to the A/C clutch through the relay and CKT 59.
Test Description: Number below refers to circled numbers on the diagnostic chart.
1. If there is no delay when switch is cycled from "OFF" to "ON," CKT 458 may be shorted to ground or the relay contacts are stuck closed.