A/C Pressure Switch Circuit Troubleshooting
A/C Pressure Switch Circuit TroubleshootingNOTE:
- If the blower motor does not run at all speeds, the A/C compressor will be inoperative. Run the self-diagnostic function, and check the 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; condenser fan, radiator fan, A/C compressor, or if the heater is inoperative. Refer to the Symptom troubleshooting index. Climate Control
- Check the A/C high-side pressure.
- Before doing symptom troubleshooting, check for powertrain DTCs. Also check for B-CAN 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.
3. Turn the ignition switch to LOCK (0).
4. Disconnect climate control unit connector A (28P).
5. Turn the ignition switch to ON (II).
6. Measure the voltage between the climate control unit connector A (28P) 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.
13. Check for continuity between the climate control unit connector A (28P) 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 climate control unit connector A (28P) 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 climate control unit connector A (28P) No. 23 terminal and the connector B (12P) No. 10 terminal.
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.