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.
Before doing symptom troubleshooting, check for powertrain DTCs (see GENERAL TROUBLESHOOTING INFORMATION ).

Disconnect the A/C pressure switch 4P connector.
Turn the ignition switch ON (II).
Measure the voltage between the No. 1 terminal of the A/C pressure switch 4P connector and body ground.

Fig 1: Measuring Voltage Between No. 1 Terminal Of A/C Pressure Switch 4P Connector And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

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

Fig 2: Checking For Continuity Between No. 1 And No. 4 Terminals Of 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 4P connector.
Disconnect climate control unit connector B (26P).
Turn the ignition switch ON (II).
Measure the voltage between the No. 4 terminal of climate control unit connector B (26P) and body ground.

Fig 3: Measuring Voltage Between No. 4 Terminal Of Climate Control Unit Connector B (26P) And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?
1. YES - Go to step 10.
2. NO - Repair the open in the wire between the climate control unit and the A/C pressure switch.
Turn the ignition switch OFF.
Measure the resistance between the No. 1 and No. 20 terminals of the climate control unit connector B (26P).

Fig 4: Measuring Resistance Between No. 1 And No. 20 Terminals Of Climate Control Unit Connector B
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is the resistance less than 24 kΩ ?
1. YES - Check for loose wire or poor connections at climate control unit connector B (26P) and at the A/C pressure switch 4P 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.
2. NO - Test the evaporator temperature sensor (see EVAPORATOR TEMPERATURE SENSOR TEST ).
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.