## A/C Pressure Switch Circuit Troubleshooting - With Climate Control

1. | Disconnect the A/C pressure switch 2P connector.

2. | Turn the ignition switch ON (II).

3. | Measure the voltage between the No. 2 terminal of the A/C pressure switch 2P connector and body ground. Is there about 5 V? YES - Go to 4. NO - Go to 18.

4. | Turn the ignition switch OFF.

5. | Check for continuity between the No. 1 and No. 2 terminals of the A/C pressure switch. Is there continuity? YES - Go to 6. NO - Go to 23.

6. | Reconnect the A/C pressure switch 2P connector.

7. | Disconnect climate control unit connector A (12P).

8. | Turn the ignition switch ON (II).

9. | Measure the voltage between the No. 5 terminal of climate control unit connector A (12P) and body ground. Is there about 5 V? YES - Go to 10. NO - Repair open in the wire between the A/C pressure switch and the climate control unit.n

10. | Turn the ignition switch OFF.

11. | Disconnect the A/C switch 5P connector.

12. | Turn the ignition switch ON (II).

13. | Measure the voltage between the No. 2 terminal of the A/C switch 5P connector and body ground. Is there battery voltage? YES - Go to 14. NO - Repair open in the wire between the No. 22 fuse in the under-dash relay box and the A/C switch.n

14. | Turn the ignition switch OFF.

15. | Test the A/C switch. Is the A/C switch OK? YES - Go to 16. NO - Repair the A/C switch.n

16. | Check for continuity between the No. 2 terminal of climate control unit connector A (12P) and the No. 1 terminal of the A/C switch 5P connector. Is there continuity? YES - Go to 17. NO - Repair open in the wire between the climate control unit and the A/C switch.n

17. | Check for continuity between the No. 2 terminal of climate control unit connector A (12P) and body ground. Is there continuity? YES - Repair short to body ground in the wire between the climate control unit and the A/C switch.n NO - Check for loose wires or poor connections at climate control unit connector A (12P), the A/C pressure switch 2P connector and at the A/C switch 5P 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.n

18. | Turn the ignition switch OFF.

19. | Reconnect the A/C pressure switch 2P connector.

20. | Make sure the A/C switch is OFF.

21. | Turn the ignition switch ON (II).

22. | Messure the voltage between the No. 28 terminal of ECM/PCM connector E (31P) and body ground with the ECM/PCM connectors connected. Is there about 5 V? YES - Repair open in the wire between the ECM/PCM and the A/C pressure switch.n NO - Check for loose wires or poor connections at ECM/PCM connector E (31P) and at the A/C pressure switch 2P connector. If the connections are good, substitute a known-good ECM/PCM, and recheck. If the symptom/indication goes away, replace the original ECM/ PCM.n

23. | Check for proper A/C system pressure. Is the pressure within specifications? YES - Replace the A/C pressure switch.n NO - Repair the A/C pressure problem.n