A/C Pressure Switch and Evaporator Temperature Sensor Circuit Troubleshooting
A/C Pressure Switch and Evaporator Temperature Sensor 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. 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.