A/C Pressure Switch Circuit Troubleshooting

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 3.


NO - Troubleshoot the blower motor circuit.


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

4.Turn the ignition switch ON (II).

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

 

Is there battery voltage?


YES - Go to 6.


NO - Go to 12.


6.Turn the ignition switch OFF.

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

 

Is there continuity?


YES - Go to 8.


NO - Go to 14.


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

9.Disconnect the climate control unit 30P connector.

10.Turn the ignition switch ON (II).

11.Measure the voltage between the No. 14 terminal of the climate control unit 30P connector and body ground.

 

Is battery voltage?


YES - Check for loose wires or poor connections at the climate control unit 30P connector 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


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

12.Make sure the A/C switch is OFF.

13.Measure the voltage between the No. 9 terminal of under-dash fuse/relay box connector F (12P) and body ground with the under-dash fuse/relay box connectors connected.

 

Is there 5V or more?


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


NO - Refer to the multiplex control system.n

NOTE: Check for multiplex codes in mode 1. Follow the troubleshooting for any codes found. If no codes are found, subsititute a known-good multiplex control unit and a PCM one at a time.


14.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