A/C Pressure Switch Circuit Troubleshooting (Without Climate Control)

A/C Pressure Switch Circuit Troubleshooting

NOTE:

- 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.

- Check the A/C high-side pressure.

- Before doing any symptom troubleshooting, check for powertrain DTCs. Initial Inspection and Diagnostic Overview Also check for B-CAN codes. Troubleshooting - B-CAN System Diagnosis Test Mode A

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. 12


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

4. Disconnect the HVAC control unit 24P connector.

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

6. Measure the voltage between the HVAC control unit 24P connector No. 21 terminal and body ground.

Is there battery voltage?
YES - Go to step 14.

NO - Go to step 7.






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

8. Disconnect the A/C pressure switch 2P connector.

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

10. Measure the voltage between the A/C pressure switch 2P connector No. 2 terminal and body ground.

Is there battery voltage?
YES - Go to step 11.

NO - Repair open in the wire between the A/C pressure switch and the MICU. If the wire is OK, substitute a known-good MICU and recheck. If the symptom goes away, replace the original MICU.






11. Check for continuity between the No. 1 and No. 2 terminals of the A/C pressure switch.

Is there continuity?
YES - Go to step 12.

NO - Replace the A/C pressure switch.






12. Connect the A/C pressure switch 2P connector No. 2 terminal to body ground with a jumper wire.

Do the compressor and fans operate?
YES - Go to step 13.

NO - Check for B-CAN codes. Troubleshooting - B-CAN System Diagnosis Test Mode A






13. Check for continuity between the HVAC control unit 24P connector No. 21 terminal and the A/C pressure switch 2P connector No. 1 terminal.

Is there continuity?
YES - Check for loose wires or poor connections at the HVAC control unit 24P connector and at the A/C pressure switch 2P connector.

NO - Repair open in the wire between the HVAC control unit and A/C pressure switch.






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

15. Measure the evaporator temperature sensor resistance between the HVAC control unit 24P connector No. 14 and No. 15 terminals.

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

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