Thermal Limiting Fuse: Testing and Inspection
A/C Pressure Switch and Thermal Protector Circuit Troubleshooting1. Turn the ignition switch ON (II).
2. Press the AUTO button, then press the A/C button and check the display.
Does the display indicate A/C on?
YES - Go to step 3.
NO - Check for loose or poor connection at the climate control connector. If the connections are OK, replace the audio-HVAC display panel.
3. Disconnect the thermal protector 3P connector.
4. Turn the ignition switch ON (II).
5. Measure the voltage between the No. 1 terminal of the thermal protector 3P connector and body ground.
Is there about 5 V or more?
YES - Go to step 6.
NO - Go to step 20.
6. Turn the ignition switch OFF.
7. Check for continuity between the No. 1 and No. 3 terminals of the thermal protector.
Is there continuity?
YES - Go to step 8.
NO - Replace the thermal protector.
8. Reconnect the thermal protector 3P connector.
9. Disconnect the A/C pressure switch 2P connector.
10. Turn the ignition switch ON (II).
11. Measure the voltage between the No. 1 terminal of the A/C pressure switch 2P connector and body ground.
Is there about 5 V or more?
YES - Go to step 12.
NO - Repair open in the wire between the A/C pressure switch and the thermal protector.
12. Turn the ignition switch OFF.
13. Check for continuity between the No. 1 and No. 2 terminals of the A/C pressure switch.
Is there continuity?
YES - Go to step 14.
NO - Go to step 21.
14. Reconnect the A/C pressure switch 2P connector.
15. Disconnect audio-HVAC display panel connector A (22P).
16. Turn the ignition switch ON (II).
17. Measure the voltage between the No. 5 terminal of audio-HVAC display panel connector A (22P) and body ground.
Is there about 5 V or more?
YES - Go to step 18.
NO - Repair open in the wire between the audio-HVAC display panel and the A/C pressure switch.
18. Turn the ignition switch off.
19. Measure the resistance between the No. 14 and No. 15 terminals of the audio-HVAC display panel connector A (22P).
Is the resistance less than 24 kOhm?
YES - Check for loose wire or poor connections at audio-HVAC display panel connector A (22P) and at the A/C pressure switch 2P connector. If the connections are good, substitute a known-good audio-HVAC display panel, and recheck. If the symptom/indication goes away, replace the original audio-HVAC display panel.
NO - Test the evaporator temperature sensor.
20. Using a backprobe set, measure the voltage between the No. 2 terminal of under-hood fuse/relay box connector H (14P) and body ground with the under-hood fuse/relay box connectors connected.
Is there 5 V or more?
YES - Repair open in the wire between the under-hood fuse/relay box and the A/C pressure switch.
NO - Check for loose or poor connections at the No. 2 terminal of the under-hood fuse/relay box. if the connections are OK, replace the under-hood fuse/relay box.
21. 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.