Air Conditioning Signal
NOTE:
This signal informs the PCM that there is a demand for cooling from the A/C system.
- Turn ignition off. Disconnect A/C pressure switch and A/C diode. See A/C SIGNAL COMPONENT LOCATIONS . Turn ignition on. Measure voltage between PCM connector terminal A9 and terminal C5. See Figure. If battery voltage exists, go to step 3). If specified voltage does not exist, go to next step.
- Turn ignition off. Disconnect PCM connector "C". Check for continuity between ground and PCM connector terminal C5. If continuity exists, repair short in wire between PCM connector and A/C pressure switch. See WIRING DIAGRAMS article. If continuity does not exist, substitute a known good PCM, then recheck for voltage. Repeat step 1). If specified voltage now exists, replace original PCM. If specified voltage still does not exist, inspect A/C system. See the A/C-HEATER SYSTEM - MANUAL article in the AIR CONDITIONING & HEAT section.
- Turn ignition off. Reconnect A/C pressure switch and A/C diode connectors. Turn ignition on. Using a fused jumper wire, momentarily connect PCM connector terminal A9 and terminal A17, several times. See Figure. If A/C compressor clutch makes a clicking sound, go to step 5). If A/C compressor clutch does not make a clicking sound, go to next step.
- Using a fused jumper wire, momentarily connect A/C clutch relay connector terminal No. 4 to ground several times. See Fig 1. See A/C SIGNAL COMPONENT LOCATIONS . If A/C compressor clutch makes a clicking sound, repair open in wire between A/C clutch relay and PCM connector terminal A17. See WIRING DIAGRAMS article. If A/C compressor clutch does not make a clicking sound, inspect A/C system. See the A/C-HEATER SYSTEM - MANUAL article in the AIR CONDITIONING & HEAT section.
- Start engine. Turn A/C and blower motor switches on. If A/C operates, A/C signal is okay. If A/C does not operate, measure voltage between PCM connector terminal A9 and terminal C5. See Figure. If less than one volt exists, substitute known-good PCM and recheck. If symptom or indication goes away, replace original PCM. If not, inspect A/C system. If less than one volt is not present, repair open in wire between A/C switch and PCM connector terminal C5. See WIRING DIAGRAMS
article.A/C SIGNAL COMPONENT LOCATIONS
A/C Component Location Clutch Relay Left front corner of engine compartment next to condenser fan relay Diode Behind glove box, taped to harness near 20-pin Red junction connector Pressure Switch Lower right front corner of engine compartment