Refrigerant Pressure Sensor / Switch: Testing and Inspection
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, or if the heater is inoperative. Refer to the symptom troubleshooting index.
- Before performing symptom troubleshooting, check for powertrain DTCs.
1. Turn the ignition switch ON (II).
2. Turn the blower switch on, and check for blower motor operation.
Does the blower motor run on all speeds?
YES - Go to step 3.
NO - Troubleshoot the blower motor circuit.
3. Turn the ignition switch OFF.
4. Disconnect the A/C pressure switch 2P connector.
5. Turn the ignition switch ON (II).
6. Measure the voltage between the No. 2 terminal of the A/C pressure switch 2P connector and body ground.
Is there battery voltage?
YES - Go to step 7.
NO - Go to step 15.
7. Turn the ignition switch OFF.
8. Check for continuity between the No. 1 and No. 2 terminals of the A/C pressure switch.
Is there continuity?
YES - Go to step 9.
NO - Go to step 17.
9. Reconnect the A/C pressure switch 2P connector.
10. Disconnect the heater control panel 30P connector.
11. Turn the ignition switch ON (II).
12. Measure the voltage between the No. 14terminal of the heater control panel 30P connector and body ground.
Is there battery voltage?
YES - Go to step 13.
NO - Repair open in the wire between the heater control panel and the A/C pressure switch.
13. Turn the ignition switch OFF.
14. Measure the resistance between the No. 2 and No. 3 terminals of the heater control panel 30P connector.
Is the resistance less than 24 kOhms?
YES - Check for loose wires or poor connections at the heater control panel 30P connector and at the A/C pressure switch 2P connector. If the connections are good, substitute a known-good heater control panel, and recheck. If the symptom/indication goes away, replace the original heater control panel.
NO - Test the evaporator temperature sensor.
15. Make sure the A/C switch is OFF.
16. Using a backprobe set, measure the voltage between the No. 9 terminal of under-dash fuse/relay box connector F (12P) and body ground with the under-dash fuse/relay box connectors connected.
Is there battery voltage?
YES - Repair open in the wire between the under-dash fuse/relay box and the A/C pressure switch.
NO - Refer to the multiplex control system troubleshooting.
NOTE: Check for multiplex codes in mode 1. Follow the troubleshooting for any codes found. If no codes are found, substitute a known-good multiplex control unit and a ECM/PCM one at a time.
17. 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.