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 climate control unit 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 kOhms?
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 - Repair cause of high resistance in the evaporator temperature circuit.
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