## A/C Pressure Switch Circuit Troubleshooting - Without 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 22.

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 27.

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

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

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

9. | Measure the voltage between the No. 2 terminal of the A/C switch 5P connector 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 A/C switch.n

10. | Turn the ignition switch OFF.

11. | Test the A/C switch. Is the A/C switch OK? YES - Go to 12. NO - Replace the A/C switch.n

12. | Disconnect the heater fan switch 7P connector.

13. | Check for continuity between the No. 1 terminal of the A/C switch 5P connector and the No. 6 terminal of the heater fan switch 7P connector. Is there continuity? YES - Go to 14. NO - Repair open in the wire between the A/C switch and the heater fan switch.n

14. | Test the heater fan switch. Is the heater fan switch OK? YES - Go to 15. NO - Replace the heater fan switch.n

15. | Check for continuity between the No. 3 terminal of the heater fan switch 7P connector and body ground. Is there continuity? YES - Go to 16. NO - Check for an open in the wire between the heater fan switch and body ground. If the wire is OK, check for poor ground at G402.n

16. | Disconnect the evaporator temperature sensor 2P connector.

17. | Measure the resistance between the No. 1 and No. 2 terminals of the evaporator temperature sensor. Is the resistance within the specifications shown on the graph? YES - Go to 18. NO - Replace the evaporator temperature sensor.n

18. | Disconnect the negative cable from the battery.

19. | Disconnect ECM/PCM connector E (31P).

20. | Check for continuity between the following terminals of ECM/PCM connector E (31P) and the evaporator temperature sensor 2P connector.
E (31P): | 2P:
No. 4 | No. 2
No. 12 | No. 1
Is there continuity? YES - Go to 21. NO - Repair any open in the wire(s) between the ECM/ PCM and the evaporator temperature sensor.n

21. | Check for continuity between the No. 12 terminal of ECM/PCM connector E (31P) and body ground. Is there continuity? YES - Repair short to body ground in the wire between the ECM/ PCM and the evaporator temperature sensor.n NO - Check for loose wires or poor connections at ECM/PCM connector E (31P), the evaporator temperature sensor 2P connector, the A/C pressure switch 2P connector, the A/C switch 5P connector and at the heater fan switch 7P 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

22. | Turn the ignition switch OFF.

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

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

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

26. | Measure 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). 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

27. | 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