A/C Pressure Switch Circuit Troubleshooting

WARNING: This page is about a different car, the 2008 Honda Pilot, 2007 Honda Pilot, and 2006 Honda Pilot. However, it is still accessible from the selected car via links, so may be relevant.

NOTE:

If the blower motor does not run at all speeds, the A/C compressor will be inoperative. Before doing this troubleshooting, check the DTC and repair the cause of the inoperative blower motor.
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 .
Before performing symptom troubleshooting, check for powertrain DTCs (see GENERAL TROUBLESHOOTING INFORMATION ).

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

Is there about 5 V?

YES - Go to step 4.

NO - Go to step 16.
Turn the ignition switch OFF.
Connect A/C pressure switch 2P connector terminal No. 2 to body ground with a jumper wire.

Fig 2: Connecting A/C Pressure Switch 2P Connector Terminal No. 2 To Body Ground With Jumper Wire
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Using the HDS, confirm the A/C switch value in the PGM-FI Data List at idle.
Does the HDS Data List show the A/C switch ON?

YES - Go to step 7

NO - Substitute a known-good PCM, and recheck. If the symptom/indication goes away, replace the orginal PCM (see PCM REPLACEMENT ).
Turn the ignition switch OFF.
Disconnect the jumper wire.
Check for continuity between the No. 1 and No. 2 terminals of the A/C pressure switch.

Fig 3: Checking For Continuity Between No. 1 & No. 2 Terminals Of A/C Pressure Switch
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Go to step 10.

NO - Go to step 20.
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 4: Measuring Voltage Between No. 23 Terminal Of Heater Control Panel 30P Connector & Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there about 5 V?

YES - Go to step 14.

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. 19 and No. 27 terminals of the heater control panel 30P connector.

Fig 5: Measuring Resistance Between No. 19 & No. 27 Terminals Of Heater Control Panel 30P Connector
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is the resistance less than 24 kΩ?

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.

NO - Repair cause of high resistance in the evaporator temperature circuit.
Turn the ignition switch OFF.
Jump the SCS line with the HDS.
NOTE: This step must be done to protect the powertrain control module (PCM) from damage.
Disconnect the PCM connector A (44P).
Check for continuity between the No. 41 terminal of PCM connector A (44P) and No. 2 terminal of the A/C pressure switch 2 connector.

Fig 6: Checking For Continuity Between Terminal Of PCM Connector A (44P) & Terminal Of A/C Pressure Switch 2 Connector
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Check for loose wires or poor connections at the PCM connector A (44P). If the connections are good, substitute a known-good PCM, and recheck. If the symptom/indication goes away, replace the original PCM, then perform the PCM idle learn procedure (see PCM IDLE LEARN PROCEDURE ).

NO - Repair open in the wire between the PCM and the A/C pressure switch.
Check for proper A/C system pressure (see A/C SYSTEM TEST ).
Is the pressure within specifications?

YES - Replace the A/C pressure switch.

NO - Repair the A/C pressure problem.