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Air Conditioning Signal
- Turn ignition off. Disconnect A/C pressure switch and A/C diode connector. Turn ignition on. Measure voltage between PCM terminals C5 and A9. See Figure. If voltage is not about 5 volts, go to next step. If voltage is about 5 volts, go to step 3).
- Turn ignition off. Disconnect PCM connector "C". Check continuity between body ground and PCM terminal C5. If continuity does not exist, substitute a known-good PCM and recheck for 5 volts as instep 1). If continuity exists, repair shorted Blue/Red wire between PCM terminal C5 and A/C pressure switch or A/C diode.
- Turn ignition off. Reconnect A/C pressure switch. Turn ignition on. Using a jumper wire, momentarily connect PCM terminals A9 and A17 together. If A/C clutch clicks, go to next step. If A/C clutch does not click, momentarily connect Black/Red wire at A/C clutch relay connector to ground. If A/C clutch clicks, repair open Black/Red wire between PCM terminal A17 and A/C relay harness connector. If A/C clutch does not click, A/C system has another problem.
- Start engine. Turn blower on. Turn A/C switch on. If A/C operates, A/C signal is okay. If A/C does not operate, measure voltage between terminals C5 (positive) and A9 (negative). If voltage is more than one volt, repair open in Blue/Red wire between PCM terminal C5 and A/C pressure switch or diode. If voltage is less than one volt, substitute a known-good PCM and recheck for symptom.