A/C Signal Circuit Troubleshooting (Climate Control System)
A/C Signal Circuit TroubleshootingNOTE:
- Do not use this troubleshooting procedure if any of the following items are operative: A/C condenser fan, radiator fan, A/C compressor. Refer to the symptom troubleshooting index. Symptom Related Diagnostic Procedures
- Before doing symptom troubleshooting, check for powertrain DTCs.
1. Connect the HDS to the DLC.
2. Start the engine.
3. Turn on the A/C on the climate control unit.
4. Check the A/C switch in the PGM-FI Data List with the HDS.
Is the A/C switch on?
YES - The A/C signal is OK at this time.
NO - Go to step 5.
5. Turn the ignition switch OFF.
6. Disconnect the climate control unit connector A (32P).
7. Measure the evaporator temperature sensor resistance between the climate control unit connector A (32P) terminals No. 8 and No. 19.
Is the resistance less than 24 kOhms?
YES - Go to step 8.
NO - Test the evaporator temperature sensor.
8. Reconnect climate control unit connector A (32P).
9. Turn the ignition switch ON (II).
10. Check that the blower motor operates at all speeds.
Does the blower motor operate at all speeds?
YES - Go to step 11.
NO - Repair the problem in the blower motor circuit.
11. Turn the ignition switch OFF.
12. Disconnect climate control unit connector A (32P).
13. Turn the ignition switch ON (II).
14. Measure the voltage between climate control unit connector A (32P) terminal No. 6 and body ground.
Is there battery voltage?
YES - Go to step 15.
NO - Repair open in the wire between the climate control unit and MICU.
15. Turn the ignition switch OFF.
16. Reconnect climate control unit connector A (32P).
17. Set the A/C button and fan control switch ON, then turn the ignition switch ON (II).
18. Measure the voltage between climate control unit connector A (32P) terminal No. 6 and body ground.
Is there 0.5 V or less?
YES - Replace the MICU.
NO - Check for loose wires or poor connections at climate control unit connector A (32P). 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.