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. Symptom Related Diagnostic Procedures
- Before performing symptom troubleshooting, check for powertrain DTCs.
1. Disconnect the A/C pressure switch 2P connector.
2. Turn the ignition switch ON (II).
3. Measure the voltage between the No. 2 terminal of the A/C pressure switch 2P connector and body ground.
Is there about 5 V?
YES - Go to step 4.
NO - Go to step 15.
4. Turn the ignition switch OFF.
5. Check for continuity between the No. 1 and No. 2 terminals of the A/C pressure switch.
Is there continuity?
YES - Go to step 6.
NO - Go to step 17.
6. Reconnect the A/C pressure switch 2P connector.
7. Disconnect the heater control panel 30P connector.
8. Turn the ignition switch ON (II).
9. Measure the voltage between the No. 12 terminal of the heater control panel 30P connector and body ground.
Is there about 5 V?
YES - Go to step 10.
NO - Repair open in the wire between the heater control panel and the A/C pressure switch.
10. Turn the ignition switch OFF.
11. Measure the resistance between the No. 7 and No. 10 terminals of the heater control panel 30P connector.
Is the resistance less than 24 kOhms?
YES - Go to step 12.
NO - Repair cause of high resistance in the evaporator temperature circuit.
12. Reconnect the heater control panel 30P connector.
13. Turn the ignition switch ON (II).
14. Check the blower motor operation at several speeds.
Does the blower motor operate at all speeds?
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 - Repair the problem in the blower motor circuit.
15. Make sure the A/C switch is OFF.
16. Using a backprobe set, measure the voltage between the No. 27 terminal of ECM connector A (32P) and body ground with the ECM connectors connected ('00-05 models) or between the No. 28 terminal of ECM connector E (31P) and body ground with the ECM connectors connected ('06 model).
Is there about 5 V?
YES - Repair open in the wire between the ECM and the A/C pressure switch.
NO - Check for loose wires or poor connections at ECM connector A (32P) ('00-05 models), or ECM connector E (31P) ('06 model). If the connections are good, substitute a known-good ECM, and recheck. If the symptom/indication goes away, replace the original ECM.
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.