A/C Pressure Switch Circuit Troubleshooting
A/C Pressure Switch Circuit TroubleshootingNOTE:
- 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. Heating/Air Conditioning
- Before doing any symptom troubleshooting, check for powertrain DTCs.
- If the blower motor does not run at all speeds, the A/C compressor will be inoperative. Before performing any other troubleshooting, repair the cause of the inoperative blower motor.
1. Check for body DTCs using B-CAN system diagnosis test mode A troubleshooting.
Are there any DTCs indicated?
YES - Do the appropriate troubleshooting for the DTC indicated.
NO - Go to step 3.
2. Refer to the PGM-FI ECU Data List.
Is the A/C switch OFF?
YES - Go to step 3.
NO - Refer to the symptom troubleshooting index. Heating/Air Conditioning
3. Disconnect the A/C pressure switch 4P connector.
4. Turn the ignition switch ON (II).
5. Measure the voltage between the A/C pressure switch 4P connector No. 4 terminal and body ground.
Is there 5 V or more?
YES - Go to step 6.
NO - Go to step 20.
6. Connect the A/C pressure switch 4P connector No. 4 terminal to body ground with a jumper wire.
7. Start the engine.
Does the compressor and fans come on?
YES - Go to step 8.
NO - Check the connection of under-hood fuse/relay box connector H (18P) No. 3 terminal. If the connection is OK, replace the under-hood fuse/relay box.
8. Disconnect a jumper wire, and turn the ignition switch OFF.
9. Check for continuity between the A/C pressure switch No. 1 and No. 4 terminals.
Is there continuity?
YES - Go to step 10.
NO - Go to step 19.
10. Reconnect the A/C pressure switch 4P connector.
11. Disconnect the HVAC control unit 30P connector.
12. Turn the ignition switch ON (II).
13. Measure the voltage between the HVAC control unit 30P connector No. 12 terminal and body ground.
Is there 5 V or more?
YES - Go to step 14.
NO - Repair the open in the wire between the HVAC control unit and the A/C pressure switch.
14. Turn the ignition switch OFF.
15. Measure the evaporator temperature sensor resistance between the HVAC control unit 30P connector No. 20 and No. 24 terminals.
Is the resistance less than 24 kohms?
YES - Go to step 16.
NO - Test the evaporator temperature sensor.
16. Reconnect the HVAC control unit 30P connector.
17. Turn the ignition switch ON (II).
18. Check that blower motor operates at all speeds.
Does the blower motor operate at all speeds?
YES - Check for loose wires or poor connections at the HVAC control unit 30P connector and at the A/C pressure switch 4P connector. If the connections are good, substitute a known-good HVAC control unit and recheck. If the symptom/indication goes away, replace the original HVAC control unit.
NO - Repair the problem in the blower motor circuit.
19. Check for proper A/C system pressure.
Is the pressure within specifications?
YES - Replace the A/C pressure switch.
NO - Repair the A/C pressure problem.
20. Disconnect under-hood relay box connector H (18P).
21. Check for continuity between the A/C pressure switch connector No. 4 terminal and under-hood relay box connector H (18P) No. 3 terminal.
Is there continuity?
YES - Go to step 22.
NO - Repair open in the wire between the relay control module and the A/C pressure switch.
22. Reconnect under-hood relay box connector H (18P).
23. Connect the A/C pressure switch connector No. 4 terminal to body ground with the jumper wire.
24. Start the engine.
Do the A/C compressor and fans come on?
YES - Replace the relay control module.
NO - Check for loose wires or poor connections. If the connections are good, check the grounds. If the grounds are good, replace the relay control module.