A/C Signal Circuit Troubleshooting

WARNING: This page does not describe the selected car, but rather 6 other vehicles, including the 2015 Honda Crosstour, 2014 Honda Crosstour, 2013 Honda Crosstour, 2012 Honda Crosstour, and 2011 Honda Accord Crosstour. 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. Run the Self-Diagnostic Function, and check for DTC B1241. Before performing any other troubleshooting, repair the cause of the inoperative blower motor.
Do not use this troubleshooting procedure if any of the following items are operative: The A/C condenser fan, the radiator fan, or the 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 ).

Turn the ignition switch to ON (II).
Check if the blower motor operates at all speeds.
Does the blower motor operate at all speeds?

YES -Go to step 3.

NO -Repair the problem in the blower motor circuit (see DTC B1241 OR DTC INDICATOR N AND A/C ON: A PROBLEM IN THE BLOWER MOTOR CIRCUIT ).
Do the sensor input display mode (see CHECK THESE ITEMS BEFORE USING THE SENSOR INPUT DISPLAY MODE ).
Is Sensor #5 (evaporator outlet air temperature) above 3°C?.

YES -Go to step 4.

NO -Go to step 9.
Turn the ignition switch to LOCK (0).
Disconnect climate control unit connector A (28P).
Turn the ignition switch to ON (II).
Measure the voltage between climate control unit connector A (28P) terminal No. 22 and body ground.

Fig 1: Measuring Voltage Between Climate Control Unit Connector A (28P) Terminal No. 22 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?

YES -Replace the climate control unit; with navigation system (see WITH NAVIGATION SYSTEM ), without navigation system (see WITH NAVIGATION SYSTEM ).

NO -Go to step 8.
Measure the voltage between driver's under-dash fuse/relay box connector F (33P) terminal No. 22 and body ground.

Fig 2: Measuring Voltage Between Driver's Under-Dash Fuse/Relay Box Connector F (33P) Terminal No. 22 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?

YES -Repair an open in the wire between the climate control unit and the driver's MICU.

NO -Check for loose wire or poor connections at driver's under-dash fuse/relay box connector F (33P) terminal No. 22. If the connections are good, substitute a known-good driver's under-dash fuse/relay box (includes the driver's MICU) and recheck. If the symptom goes away, replace the original driver's under-dash fuse/relay box (includes the driver's MICU) (see DRIVER'S UNDER-DASH FUSE/RELAY BOX (MICU) REMOVAL AND INSTALLATION ).
Turn the ignition switch to LOCK (0).
Disconnect climate control unit connectors A (28P) and B (12P).
Measure the evaporator temperature sensor resistance between climate control unit connector A (28P) terminal No. 20 and connector B (12P) terminal No. 9.

Fig 3: Measuring Evaporator Temperature Sensor Resistance Between Climate Control Unit Connector A (28P) Terminal No. 20 And Connector B (12P) Terminal No. 9
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is the resistance less than 24 kΩ?

YES -Check for loose wires or poor connections at the climate control unit connectors. If the connections are good, substitute a known-good climate control unit and recheck. If the symptom goes away, replace the original climate control unit; with navigation system (see WITH NAVIGATION SYSTEM ), without navigation system (see WITH NAVIGATION SYSTEM ).

NO -Go to step 12.
Disconnect the evaporator temperature sensor 2P connector.
Check for continuity between climate control unit connector A (28P) terminal No. 20 and evaporator temperature sensor 2P connector terminal No. 1.

Fig 4: Checking For Continuity Between Climate Control Unit Connector A (28P) Terminal No. 20 And Evaporator Temperature Sensor 2P Connector Terminal No. 1
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to step 14.

NO -Repair an open in the wire between the climate control unit and the evaporator temperature sensor.
Check for continuity between climate control unit connector B (12P) terminal No. 9 and evaporator temperature sensor 2P connector terminal No. 2.

Fig 5: Checking For Continuity Between Climate Control Unit Connector B (12P) Terminal No. 9 And Evaporator Temperature Sensor 2P Connector Terminal No. 2
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Test the evaporator temperature sensor (see EVAPORATOR TEMPERATURE SENSOR TEST ).

NO -Repair an open in the wire between the climate control unit and the evaporator temperature sensor.