Refrigerant Pressure Sensor / Switch: Testing and Inspection

A/C Pressure Switch and Evaporator Temperature Sensor Circuit Troubleshooting

NOTE:
- 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. Disconnect the A/C pressure switch 4P connector.
2. Turn the ignition switch ON (II).




3. Measure the voltage between the No. 1 terminal of the A/C pressure switch 4P connector and body ground.

Is there battery voltage?

YES - Go to step 4.

NO - Repair open in the wire between the A/C diode, the ECM and the A/C pressure switch.

4. Turn the ignition switch OFF.




5. Check for continuity between the No. 1 and No. 4 terminals of the A/C pressure switch.

Is there continuity?

YES - Go to step 6.

NO - Go to step 15.

6. Reconnect the A/C pressure switch 4P connector.
7. Disconnect climate control unit connector B (22P).
8. Turn the ignition switch ON (II).




9. Measure the voltage between the No. 17 terminal of climate control unit connector B (22P) and body ground.

Is there 5V or more?

YES - Go to step 10.

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

10. Turn the ignition switch OFF.




11. Measure the resistance between the No. 3 and No. 5 terminals of the climate control unit connector B (22P).

Is the resistance less than 24 kOhm?

YES - Go to step 12.

NO - Test the evaporator temperature sensor.

12. Reconnect the climate control unit connector B (22P).
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 climate control unit connector B (22P) and at the A/C pressure switch 4P connector. If the connections are good, substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit.

NO - Repair the problem in the blower motor circuit.

15. 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.