Component Diagnostic Charts/Tests

Fig. 010 - Wiring Diagram for Chart C-10A A/C Clutch Control. VIN 0, VIN 2, VIN R:

A/C CLUTCH CONTROL - CHART C-10

ECM control of the A/C clutch improves idle quality and performance by;
a. delaying clutch apply until the idle air rate is increased.
b. releasing clutch when idle speed is too low.
c. releasing clutch at wide open throttle.
d. smooths cycling of the compressor by providing additional fuel at the instant clutch is applied.
Turning on air conditioning supplies CKT 459 battery voltage to the clutch control relay and terminal 21 of the white ECM connector. After a time delay of about 1/2 second the ECM will ground terminal 7 of the black ECM connector, CKT 458, and close the control relay.

Fig. 007 Chart C-10 A/C Clutch Control (1 of 2):

Fig. 009 Chart C-10 A/C Clutch Control (2 of 2):

1. Checks for low refrigerant as cause for no A/C.
2. This and following tests check for faulty A/C control relay.
3. Checks for faulty cycling switch.