A/C Pressure Switch Circuit Troubleshooting
A/C Pressure Switch Circuit TroubleshootingNOTE:
- If the blower motor does not run at all speeds, the A/C compressor will be inoperative. Before doing this troubleshooting, check the DTC and repair the cause of the inoperative blower motor.
- Do not use this troubleshooting procedure if any of the following items are operative; condenser fan, radiator fan, A/C compressor, or if the heater is inoperative. Refer to the symptom troubleshooting index. Heating/Air Conditioning
- Before doing 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 12.
4. Turn the ignition switch OFF.
5. Connect A/C pressure switch 2P connector terminal No. 2 to body ground with a jumper wire.
6. Using the HDS, confirm the A/C switch value in the PGM-FI Data List at idle.
Does the HDS Data List show the A/C switch ON?
YES - Go to step 7.
NO - Substitute a known-good PCM, and recheck. If the symptom/indication goes away, replace the original PCM.
7. Turn the ignition switch OFF.
8. Disconnect the jumper wire.
9. Check for continuity between the No. 1 and No. 2 terminals of the A/C pressure switch.
Is there continuity?
YES - Go to step 10.
NO - Go to step 20.
10. Reconnect the A/C pressure switch 2P connector.
11. Disconnect the heater control panel 30P connector.
12. Turn the ignition switch ON (II).
13. Measure the voltage between the No. 23 terminal of the heater control panel 30P connector and body ground.
Is there about 5 V?
YES - Go to step 14.
NO - Repair open in the wire between the heater control panel and the A/C pressure switch.
14. Turn the ignition switch OFF.
15. Measure the resistance between the No. 19 and No. 27 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 - Repair cause of high resistance in the evaporator temperature circuit.
16. Turn the ignition switch OFF.
17. Jump the SCS line with the HDS.
NOTE: This step must be done to protect the powertrain control module (PCM) from damage.
18. Disconnect the PCM connector A (44P).
19. Check for continuity between the No. 41 terminal of PCM connector A (44P) and No. 2 terminal of the A/C pressure switch 2P connector.
Is there continuity?
YES - Check for loose wires or poor connections at the PCM connector A (44P). If the connections are good, substitute a known-good PCM, and recheck. If the symptom/indication goes away, replace the original PCM.
NO - Repair open in the wire between the PCM and the A/C pressure switch.
20. 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.