A/C Signal Circuit Troubleshooting (Climate Control)

HVAC

A/C Signal Circuit Troubleshooting

A/C Signal Circuit Troubleshooting

NOTE:
* Do not use this troubleshooting procedure if any of the following items are operative with the A/C button and the fan control button to ON: The A/C condenser fan, the radiator fan, or the A/C compressor. Refer to the symptom troubleshooting index.
* Do not use this troubleshooting procedure if the A/C system pressure is abnormal.
* Before doing symptom troubleshooting, check for PGM-FI DTCs How To Troubleshoot The Fuel And Emissions Systems.

1. Blower motor operation check:

Blower motor operation check
-1. Turn the ignition switch to ON (II).

-2. Check that the blower motor operates at all speeds.

Does the blower motor operate at all speeds?
-YES- Go to step 2.
-NO- Repair the problem in the blower motor circuit.

2. Climate control system check 1:

Climate control system check 1
-1. Start the engine.

-2. Set the A/C button and the fan control button to ON.

-3. Do the sensor input display mode.

Is Sensor #5 (evaporative outlet air temperature) above 3°C?
-YES- Go to step 3.
-NO- Go to step 7.

3. A/C pressure check:

A/C pressure check
-1. Turn the ignition switch to LOCK (0).

-2. Connect the HDS to the DLC.

-3. Start the engine.

-4. Set the A/C button and the fan control button to ON.

-5. Using the HDS, confirm the following value in the PGM-FI Data List at idle.





Is the value within specifications?
-YES- Go to step 4.
-NO- Go to the A/C system test result.

4. Climate control system check 2:

Climate control system check 2
-1. Using the HDS, confirm the following values in the PGM-FI Data List at idle.





Are all the values within specifications?
-YES- Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM (K24Z7 engine) Service and Repair or ECM/PCM (except K24Z7 engine) and recheck.
-NO- A/C switch is OFF, go to step 5.
-NO- A/C switch is ON and A/C clutch is OFF, go to the A/C compressor clutch circuit troubleshooting A/C Compressor Clutch Circuit Troubleshooting (Climate Control).

5. Open wire check (ACS line):

Open wire check (ACS line)
-1. Disconnect the following connector.





-2. Turn the ignition switch to ON (II).

-3. Measure the voltage between test points 1 and 2.









Is there battery voltage?
-YES- The ACS wire is OK. Go to step 6.
-NO- Repair an open in the wire between the climate control unit and the MICU.

6. Climate control unit ACS line check:

Climate control unit ACS line check
-1. Turn the ignition switch to LOCK (0).

-2. Reconnect the climate control unit 32P connector.

-3. Turn the ignition switch to ON (II).

-4. Set the A/C button and the fan control button to ON.

-5. Measure the voltage between test points 1 and 2.









Is there 0.2 V or less?
-YES- Replace the MICU Service and Repair.
-NO- Replace the climate control unit . Service and Repair

7. Evaporator temperature sensor check:

Evaporator temperature sensor check
-1. Turn the ignition switch to LOCK (0).

-2. Disconnect the following connector.





-3. Measure the resistance between test points 1 and 2.









Is the resistance less than 24 kOhms?
-YES- Replace the climate control unit . Service and Repair
-NO- Test the evaporator temperature sensor Service and Repair.