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 heater control panel connector A (14P).
5. Turn the ignition switch ON (II).
6. Measure the voltage between the No. 4 terminal of heater control panel connector A (14P) and body ground.
Is there battery voltage?
YES - Go to step 7.
NO - Go to step 12.
7. Start the engine.
8. Connect the No. 4 terminal of heater control panel connector A (14P) to body ground with a jumper wire.
Does the A/C system come on?
YES - Go to step 9.
NO - Refer to the multiplex control system.
9. Turn the ignition switch OFF.
10. Disconnect heater control panel connector B (22P).
11. Measure the resistance between the No. 2 terminal of the heater control panel connector A (14P) and the No. 7 terminal of the heater control panel connector B (22P).
Is there resistance less than 24 kOhms?
YES - Check for loose wires or poor connections at heater control panel connector A (14P) and B (22P) 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.
12. Using the Backprobe Set, connect the No. 9 terminal of under-dash fuse/relay box connector F (12P)to body ground with a jumper wire.
Does the A/C system come on?
YES - Go to step 13.
NO - Refer to the multiplex control system.
NOTE: Check for multiplex codes in mode 1. Follow the troubleshooting for any codes found. If no codes are found, substitute known-good multiplex control unit and a ECM one at a time.
13. Disconnect the A/C pressure switch 2P connector and under-dash fuse/relay box connector F (12P).
14. Check for continuity between the No. 2 terminal of the A/C pressure switch 2P connector and the No. 9 terminal of under-dash fuse relay box connector F (12P).
Is there continuity?
YES - Go to step 15.
NO - Repair open in the wire between the under-dash fuse/relay box and the A/C pressure switch.
15. Check for continuity between the No. 1 and No. 2 terminals of the A/C pressure switch.
Is there continuity?
YES - Repair open in the wire between the heater control panel and the A/C pressure switch.
NO - Go to step 16.
16. 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.