A/C Pressure Switch Circuit Troubleshooting

1. Disconnect the A/C pressure switch 4P connector.
2. Turn the ignition switch ON (II).




3. Measure the voltage between the No. 1 terminal of the A/C pressure switch 4P connector and body ground.

Is there battery voltage?

YES - Go to step 4.

NO - Repair open in the wire between A/C diode A, the PCM, and the A/C pressure switch.

4. Turn the ignition switch OFF.




5. Check for continuity between the No. 1 and No. 4 terminals of the A/C pressure switch.

Is there continuity?

YES - Go to step 6.

NO - Go to step 10.

6. Reconnect the A/C pressure switch 4P connector.




7. Disconnect climate control unit connector B (26P).
8. Turn the ignition switch ON (II).
9. Measure the voltage between the No. 4 terminal of climate control unit connector B (26P) and body ground.

Is there battery voltage?

YES - Check for loose wires or poor connections at climate control unit connector B (26P) and at the A/C pressure switch 4P connector. If the connections are good, substitute a known-good climate control unit, and recheck. If the symptom/ indication goes away, replace the original climate control unit.

NO - Repair the open in the wire between the climate control unit and the A/C pressure switch.

10. Check for proper A/C system pressure.

Is the pressure within specifications?

YES - Replace the A/C pressure switch.

NO - Repair the A/C pressure problem.