Chart C-10, A/C Clutch Control Circuit Diagnosis 2.5L & 2.8L: Notes

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

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, ECM will ground ECM terminal A4, closing control relay and engaging A/C compressor clutch.

1. 3)
   
   Checks for faulty cycling switch. Solenoids and relays are turned on and off by 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 set. Solenoid and relay coil resistance should be greater than 20 ohms.