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A/C Compressor Does Not Operate

NOTE: Ensure A/C system is properly charged. When checking A/C compressor operation or for battery voltage, ensure blower motor switch is not in OFF position. Ensure A/C switch is in on (latched) position. Observe A/C indicator light and go to test listed below. Check for Powertrain Control Module (PCM) Diagnostic Trouble Codes (DTCs). See appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
  1. Check A/C fuse (10-amp) located in underhood fuse block. If fuse is okay, go to step  3 . If fuse is blown, go to next step.
  2. Check for a short to ground in Dark Green wire between underhood fuse block Gray 68-pin connector terminal C1 and A/C compressor. Remove A/C diode from underhood fuse block and ensure proper operation. Ensure resistance of compressor clutch coil is 3-4 ohms while hot and cold. Replace blown fuse(s) and perform repairs as necessary. Ensure proper compressor operation.
  3. Turn ignition off. Replace A/C control relay in underhood fuse block with a known-good relay (keep old relay). Turn ignition on. Check A/C compressor operation. If A/C compressor operates, discard old relay. If A/C compressor does not operate, turn ignition off, reinstall original relay and go to next step.
  4. Turn ignition on. Check for voltage between ground and A/C compressor clutch connector Dark Green wire terminal "A". If battery voltage is not present, turn ignition off and go to next step. If battery voltage is present, replace A/C compressor clutch. Ensure proper compressor operation.
  5. Locate high/low pressure cut-out switch on liquid line, forward of left front strut tower. Turn ignition on. Check for voltage between ground and high/low pressure cut-out switch connector terminal "A" (Dark Green wire). If battery voltage is present, turn ignition off and go to next step. If battery voltage is not present, check high/low pressure cut-out switch for continuity between terminals "A" and "B". If continuity is not present, replace high/low pressure cut-out switch. If continuity is present, check for open in Light Green wire between high/low pressure cut-out switch and A/C-heater control panel, 12-pin connector terminal "C". If Light Green wire is okay, replace A/C-heater control panel. Ensure proper compressor operation.
  6. Locate BCM connector behind left side of dash. Turn ignition on. Check for voltage between ground and BCM connector J3 terminal A10 (Dark Green wire). If battery voltage is not present, go to next step. If battery voltage is present, turn ignition off and go to step  8 .
  7. Turn ignition off. Connect jumper wire between high/low pressure cut-out switch connector terminals "A" (Dark Green wire) and "B" (Light Green wire). Turn ignition on. Check for voltage between ground and BCM connector J3 terminal A10 (Dark Green wire). If battery voltage is present, replace high/low pressure cut-out switch. If battery voltage is not present, repair open in Dark Green wire between BCM and high/low pressure cut-out switch. Ensure proper compressor operation.
  8. Disconnect PCM connector. Connect a jumper wire between ground and PCM connector J2 terminal No. 21 (Gray wire). Turn ignition on. If compressor does not operate, turn ignition off and check for open in Gray wire. If compressor operates, replace PCM. Ensure proper compressor operation.
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