Chart C-10: A/C Clutch Control: Notes

When an A/C mode is selected on the A/C control switch, ignition voltage is supplied to the compressor low pressure switch. If there is sufficient A/C refrigerant charge, the low pressure switch will be closed and complete the circuit to the closed high pressure cut-off switch and to circuits No. 67 and 366. The voltage on circuit No. 366 to the ECM is shown by the "SCAN" tester as a A/C request "ON" (voltage present) or "OFF" (no voltage). When a request for A/C is seen by the ECM, the ECM will ground circuit No. 459 of the A/C clutch control relay, the relay contact will close, and current will flow from circuit No. 366 to circuit No. 59 and engage the A/C compressor clutch. A "SCAN" tester will show the grounding of circuit No. 459, as A/C Clutch "ON". Also, when voltage is seen by the ECM on Circuit No. 366, the cooling fan will be turned on.