DTC B1235 (3) (HVAC Control Unit)

DTC B1235 or DTC indicator 3  : A problem in the air mix control motor circuit, linkage, door, or motor (front)

DTCs (AC)

1. Problem verification

   -1. Clear the DTCs with the HDS.

   -2. Turn the vehicle to the OFF (LOCK) mode, then the ON mode.

   -3. Do the Self-Diagnostic Function with the HDS or the HVAC control unit .

   -4. Check for DTCs.

   DTC Description	DTC
   B1235 A problem in the air mix control motor circuit, linkage, door, or motor (front)

   Is DTC B1235 or 3 indicated?

   YES 

   Go to step 2.

   NO 

   Intermittent failure. Check for loose wires or poor connections on the front air mix control motor circuit.

2. Open wire check (M HOT AS line)

   -1. Turn the vehicle to the OFF (LOCK) mode.

   -2. Disconnect the following connectors.

   HVAC control unit connector A (32P)

   Front air mix control motor 7P connector

   -3. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	HVAC control unit connector A (32P): disconnected
   	Front air mix control motor 7P connector: disconnected
   Test point 1	HVAC control unit connector A (32P) No. 10
   Test point 2	Front air mix control motor 7P connector (female terminals) No. 6:

   Courtesy of HONDA, U.S.A., INC.

   Is there continuity?

   YES 

   The M HOT AS wire is not open. Go to step 3.

   NO 

   Repair an open in the wire between the HVAC control unit and the front air mix control motor.

3. Open wire check (M COOL AS line)

   -1. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	HVAC control unit connector A (32P): disconnected
   	Front air mix control motor 7P connector: disconnected
   Test point 1	HVAC control unit connector A (32P) No. 9
   Test point 2	Front air mix control motor 7P connector (female terminals) No. 7:

   Courtesy of HONDA, U.S.A., INC.

   Is there continuity?

   YES 

   The M COOL AS wire is not open. Go to step 4.

   NO 

   Repair an open in the wire between the HVAC control unit and the front air mix control motor.

4. Shorted wire check (M HOT AS line)

   -1. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	HVAC control unit connector A (32P): disconnected
   	Front air mix control motor 7P connector: disconnected
   Test point 1	HVAC control unit connector A (32P) No. 10
   Test point 2	Body ground

   Is there continuity?

   YES 

   Repair a short to body ground in the wire between the HVAC control unit and the front air mix control motor.

   NO 

   The M HOT AS wire is OK. Go to step 5.

5. Shorted wire check (M COOL AS line)

   -1. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	HVAC control unit connector A (32P): disconnected
   	Front air mix control motor 7P connector: disconnected
   Test point 1	HVAC control unit connector A (32P) No. 9
   Test point 2	Body ground

   Is there continuity?

   YES 

   Repair a short to body ground in the wire between the HVAC control unit and the front air mix control motor.

   NO 

   The M COOL AS wire is OK. Go to step 6.

6. Front air mix control motor check

   -1. Test the front air mix control motor .

   Is the front air mix control motor OK?

   YES 

   Replace the HVAC control unit .

   NO 

   Replace the front air mix control motor , or repair the front air mix control linkage or door.