A/C Pressure Switch Circuit Troubleshooting - With Climate Control

NOTE:


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 5 V or more?


YES - Go to 4.


NO - Go to 18.


4.Turn the ignition switch OFF.

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

 

Is there continuity?


YES - Go to 6.


NO - Go to 23.


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

7.Disconnect climate control unit 28P connector.

8.Turn the ignition switch ON (II).

9.Measure the voltage between the No. 26 terminal of climate control unit 28P connector and body ground.

 

Is there 5 V or more?


YES -

  • With ETCS: Go to 10.
  • Without ETCS: Go to 12.

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

10.Turn the ignition switch OFF.

11.Check for continuity between the No. 21 terminal and the No. 18 terminal of climate control unit 28P connector.

 

Is there resistance less than 24 k ohms?


YES - Go to 15.


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

12.Turn the ignition switch OFF.

13.Disconnect PCM connector E (31P).

14.Check for continuity between the No. 22 terminal of climate control unit 28P connector and the No. 4 terminal of the PCM connector E (31P).

 

Is there resistance less than 24 k ohms?


YES - Go to 15.


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


15.Reconnect climate control unit 28P connector and PCM connector E (31P) (without ETCS).

16.Turn the ignition switch ON (II).

17.Check that blower motor operates at all speeds.

Does the blower motor operate at all speeds?


YES - Check for loose wires or poor connections at climate control unit 28P 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 the problem in the blower motor circuit.n


18.Turn the ignition switch OFF.

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

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

21.Turn the ignition switch ON (II).

22.Measure the voltage between the No. 40 terminal of ECM connector E (40P) (with ETCS) or the No. 28 terminal of PCM connector E (31P) (without ETCS) and body ground with the ECM/PCM connectors connected.

With ETCS 

Without ETCS 

Is there 5 V or more?


YES - Repair open in the wire between the ECM/PCM and the A/C pressure switch.n


NO - Check for loose wires or poor connections at ECM connector E (40P) (with ETCS) or PCM connector E (31P) (without ETCS). If the connections are good, substitute a known-good ECM/PCM, and recheck. If the symptom/indication goes away, replace the original  ECM/ PCM.n


23.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