Climate Control Unit A/C Signal Circuit Troubleshooting

Climate Control Unit A/C Signal Circuit Troubleshooting

NOTE:

- If the blower motor does not run at all speeds, the A/C compressor will be inoperative. Run the self-diagnostic function, and check for DTC B1241. Before performing any other troubleshooting, repair the cause of the inoperative blower motor.

- Do not use this troubleshooting procedure if any of the following items are operative: The condenser fan, the radiator fan, or the A/C compressor, or if the heater is inoperative. Refer to the symptom troubleshooting index.

- Before doing symptom troubleshooting, check for powertrain DTCs. Reading and Clearing Diagnostic Trouble Codes

1. Turn the ignition switch to ON (II).

2. Check if the blower motor operates at all speeds.

Does the blower motor operate at all speeds?
YES - Go to step 3.

NO - Repair the problem in the blower motor circuit. B1241


3. Do the sensor input display mode. Initial Inspection and Diagnostic Overview

Is Sensor #5 (evaporative outlet air temperature) above 3 °C?
YES - Go to step 4.

NO - Go to step 12.


4. Using the HDS, confirm the following values in the PGM-FI Data List at idle.





Are all the values within specifications?
YES - Go to step 5.

NO - Troubleshoot the value that is not within the specifications.


5. Turn the ignition switch to LOCK (0).

6. Disconnect climate control unit connector A (28P).

7. Turn the ignition switch to ON (II).

8. Measure the voltage between climate control unit connector A (28P) terminal No. 21 and body ground.

Is there battery voltage?
YES - Go to step 9.

NO - Go to step 11.






9. Connect climate control unit connector A (28P) terminal No. 21 to body ground with a jumper wire.

10. Turn the ignition switch to ON (II).

Does the A/C system come on?
YES - Replace the climate control unit.

NO - Check for loose wire or poor connections at climate control unit connector A (28P) and under-dash fuse/relay box connector F (33P). If the connections are good, substitute a known-good climate control unit, and recheck. If the symptom goes away, replace the original climate control unit.






11. Measure the voltage between driver's under-dash fuse/relay box connector F (33P) terminal No. 5 and body ground.

Is there battery voltage?
YES - Repair an open in the wire between the climate control unit and the MICU.

NO - Check for loose wire or poor connections at driver's under-dash fuse/relay box connector F (33P) terminal No. 5. If the connections are good, substitute a known-good MICU and recheck. If the symptom goes away, replace the original MICU.






12. Turn the ignition switch to LOCK (0).

13. Disconnect climate control unit connectors A (28P) and B (12P).

14. Measure the evaporator temperature sensor resistance between climate control unit connector A (28P) terminal No. 23 and connector B (12P) terminal No. 10.

Is the resistance less than 24 kOhms?
YES - Check for loose wires or poor connections at the climate control unit connectors. If the connections are good, substitute a known-good climate control unit and recheck. If the symptom goes away, replace the original climate control unit.

NO - Test the evaporator temperature sensor. Evaporator Temperature Sensor Test