CHART C-10, A/C CLUTCH CONTROL CKT DIAGNOSIS 2.5/2.8L (2 Of 2): Notes

The ECM controls the A/C clutch engagement to improve idle quality and performance by delaying clutch engagement until idle speed is increased, disengages clutch when idle speed is too low, and smooths cycling of compressor by providing additional fuel the instant clutch is applied.

Turning on A/C switch supplies battery voltage to clutch control relay terminal "B" and ECM terminal B8. After a delay of about .5 seconds, the ECM will ground ECM terminal A4, closing the control relay and engages A/C compressor clutch.

1. 3)  Checks for faulty cycling switch. Solenoids and relays are turned on and off by the ECM, using "drivers". Each driver is a part of a group of 4, called quad-drivers. Failure of one driver can damage any other driver in the set. Solenoid and relay coil resistance should be greater than 20 ohms.