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Control Module HVAC: Description and Operation
With the ignition switch in ON, battery voltage is applied to the coil of the blower relay from fuse 8. With the blower switch in any position except OFF, ground is provided to the coil of the blower relay through the blower switch. Battery voltage is then applied to the A/C switch through the blower fuse, the closed contacts of the blower relay and the fuse 22. With the A/C switch in ON, the engine control module (ECM) will ground the coil of the A/C control relay after a short delay to adjust idle speed. Battery voltage will then be applied to the compressor clutch from A/C compressor fuse and the closed contacts of the A/C relay, to make the A/C compressor run.