A/C Signal Circuit Troubleshooting (Climate Control)

A/C Signal Circuit Troubleshooting

NOTE:

- If the blower does run, or if there is a blower motor DTC, the compressor and the cooling fans will not operate (No signal).
- 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.
- Before doing any symptom troubleshooting, check for powertrain DTCs Initial Inspection and Diagnostic Overview.

1. Connect the HDS to the DLC and check for blower motor DTCs.

Are there any DTCs?

YES -

Do the appropriate DTC troubleshooting.

NO -

Go to step 2.

2. Start the engine.

3. Turn on the A/C.

4. Check the blower motor operates at all speeds.

Does the blower motor operate at all speeds?

YES -

Go to step 5.

NO -

Repair the problem in the blower motor circuit B1241.

5. 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 6.

6. Check the evaporator temperature sensor input to the climate control unit.

If the evaporator temperature sensor #5 reading above 0 °C (32 °F)?

YES -

Go to step 10.

NO -

Go to step 7.

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

8. Disconnect climate control unit connector A (24P).

9. Measure the evaporator temperature sensor resistance between climate control unit connector A (24P) terminals No. 13 and No. 18.





Is the resistance less than 24 kOhms?

YES -

Go to step 11.

NO -

Test the evaporator temperature sensor Testing and Inspection.

10. Turn the ignition switch to LOCK (0), then disconnect climate control unit connector A (24P).

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

12. Measure the voltage between climate control unit connector A (24P) terminal No. 17 and body ground.





Is there battery voltage?

YES -

Go to step 13.

NO -

Repair an open in the wire between the climate control unit and the MICU.

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

14. Reconnect climate control unit connector A (24P).

15. Set the A/C button and the fan control switch to ON, then turn the ignition switch to ON (II).

16. Measure the voltage between climate control unit connector A (24P) terminal No. 17 and body ground.





Is there 0.5 V or less?

YES -

Replace the under-dash fuse/relay box Under-Dash Fuse/Relay Box Removal and Installation.

NO -

Check for loose wires or poor connections at climate control unit connector A (24P). 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 Climate Control Unit Removal/Installation.