A/C Pressure Switch Circuit Troubleshooting

NOTE: Do not use this troubleshooting procedure if the following items are operative; condenser fan, radiator fan, A/C compressor, or if the heater is inoperative, Refer to the symptom troubleshooting index.

1.Check for body DTCs in test mode A of the MICS.

Are the any DTCs indicated?


YES - Do the appropriate troubleshooting for the DTC indicated.n


NO - Go to 2.


2.Disconnect the A/C pressure switch 2P connector.

3.Turn the ignition switch ON (II).

4.Measure the voltage between the No. 1 terminal of the A/C pressure switch 2P connector and body ground.

Is there 5 V or more?


YES - Go to 5.


NO - Go to 14.


5.Turn the ignition switch OFF.

6.Check for continuity between the No. 1 and No. 2 terminals of the A/C pressure switch.

Is there continuity?


YES - Go to 7.


NO - Go to 15.


7.Reconnect the A/C pressure switch 2P connector.

8.Disconnect the climate control unit connector A ( 22P).

9.Turn the ignition switch ON (II).

10.Measure the voltage between the No. 5 terminal of the climate control unit connector A (22P) and body ground.

Is there 5 V or more?


YES - Go to 11.


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

11.Turn the ignition switch off.

12.Measure the resistance between the No. 14 and No. 15 terminals of the climate control unit connector A (22P).

Is the resistance less than 24k ohms?


YES - Go to 13.


NO - Repair cause of high resistance in the evaporator temperature circuit.n


13.Perform the A/C communication in the Self-Diagnostic Function to obtain the IS-BUS communication verification status.

Is the communication OK?


YES - Check for loose wire or poor connections at climate control unit connector A (22P) and at the A/C pressure switch 2P connector. If the connections are good, substitute a known-good climate control unit and printed circuit board, and recheck. If the symptom/indication goes away, replace the original climate control unit and printed circuit board.n


NO - Check for loose wire or poor connections at climate control unit connector A (22P) and at the A/C pressure switch 2P 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.n

14.Measure the voltage between the No. 2 terminal of under-hood fuse/relay box connector H (14P) and body ground with the under-hood fuse/relay box connectors connected.

Is there 5 V or more?


YES - Repair open in the wire between the under-hood fuse/relay box and the A/C pressure switch.n


NO - Check for loose or poor connections at the No. 2 terminal of the under-hood fuse/relay box. if the connections are OK, replace the under-hood fuse/relay box.n


15.Check for proper A/C system pressure.

Is the pressure within specifications?


YES - Replace the A/C pressure switch.n


NO - Repair the A/C pressure problem.n