A/C Pressure Switch Circuit Troubleshooting

NOTE: 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.

Disconnect the A/C pressure switch 2P connector.
Turn the ignition switch ON (II).
Measure the voltage between the No. 2 terminal of the A/C pressure switch 2P connector and body ground.

Fig 1: Measuring The Voltage Between The No. 2 Terminal Of The A/C Pressure Switch 2P Connector & Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?
1. YES - Go to step 4.
2. NO - Go to step 11.
Turn the ignition switch OFF.
Check for continuity between the No. 1 and No. 2 terminals of the A/C pressure switch.

Fig 2: Checking For Continuity Between The No. 1 & No. 2 Terminals Of The A/C Pressure Switch
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?
1. YES - Go to step 6.
2. NO - Go to step 12.
Reconnect the A/C pressure switch 2P connector.
Disconnect the heater control panel 30P connector.
Turn the ignition switch ON (II).
Measure the voltage between the No. 23 terminal of the heater control panel 30P connector and body ground.

Fig 3: Measuring The Voltage Between The No. 23 Terminal Of The Heater Control Panel 30P Connector & Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?
1. YES - Go to step 10.
2. NO - Repair open in the wire between the heater control panel and the A/C pressure switch.
Turn the ignition switch OFF. Measure the resistance between the No. 3 and No. 4 terminals of the heater control panel 30P connector.

Fig 4: Measuring The Resistance Between The No. 3 & No. 4 Terminals Of The Heater Control Panel 30P Connector
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is the resistance less than 24 k ohms?
1. 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.
2. NO - Repair cause of high resistance in the evaporator temperature circuit.
Using a backprobe set, measure the voltage between the No. 27 terminal of PCM connector A (32P) and body ground with the PCM connectors connected.

Fig 5: Measuring The Voltage Between The No. 27 Terminal Of PCM Connector A (32P) & Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?
1. YES - Check for loose wires or poor connections at the PCM connector A (32P). If the connections are good, substitute a known-good PCM, and recheck. If the symptom/indication goes away, replace the original PCM.
2. NO - Repair open in the wire between the PCM and the A/C pressure switch.
Check for proper A/C system pressure.
Is the pressure within specifications?
1. YES - Replace the A/C pressure switch.
2. NO - Repair the A/C pressure problem.