A/C Pressure Switch Circuit Troubleshooting

NOTE: Do not use this troubleshooting procedure if 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.

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.■
NO | - | Go to Step 2 .

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

1. Turn the ignition switch ON (II).

1. 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 Step 5 .
NO | - | Go to Step 14 .

1. Turn the ignition switch OFF.

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

Is there continuity?

YES | - | Go to Step 7 .
NO | - | Go to Step 15 .

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

1. Disconnect climate control unit connector A (22P).

1. Turn the ignition switch ON (II).

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

Is there 5 V or more?

YES | - | Go to Step 11 .
NO | - | Repair open in the wire between the climate control unit and the A/C pressure switch.■

1. Turn the ignition switch OFF.

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

Is the resistance less than 24 kΩ?

YES | - | Go to Step 13 .
NO | - | Repair cause of high resistance in the evaporator temperature circuit.■

1. 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.■
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 .■

1. 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.■
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.■

1. 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.■