Automatic Climate Control, ACC

B2400








Stepping motor, air distribution flap. Open circuit
Stepping motor, air distribution flap. Short to ground

Fault symptoms
Perceive temperature in cabin too high or too low compared to the set temperature

The air Distribution does not correspond with the illuminated symbol in the ACC window

Conditions
The following conditions apply:
- When the current on one of the control module stepping motor outputs exceeds a certain value the diagnostic trouble code for short circuit will be set.
- If one of the stepping motor outputs detects that the standing current is lower than 55 mA, then the diagnostic trouble code for open circuit is set.
- Continuous monitoring and when calibrating.





Diagnostic procedure

1. Checking operating current to stepping motor winding 1
- Unplug connector: Motor, air distribution - defroster/panel/floor: (221a).





- Connect a test lamp between pins 1 and 3 on the female connector.





- Operate the calibration function to run the stepping motor.





- Both the red and the green LED should light up on the test lamp.

Is the function correct?
YES
- Go to step 2.
NO
- Rectify lead in question.
- Go to step 3.





2. Checking operating current to stepping motor winding 2
- Connect a test lamp between pins 4 and 6 on the female connector.





- Operate the calibration function to run the stepping motor.





- Both the red and the green LED should light up on the test lamp.

Is the function correct?
YES
- Replace: Motor, air distribution - defroster/panel/floor.
- Go to step 3.
NO
- Rectify lead in question.
- Go to step 3.





3. Final check
- Delete diagnostic trouble codes in all Systems.





- Carry out a function check.
- Evaluate the function check.
- Check that the diagnostic trouble code does not recur.

Does the diagnostic trouble code recur?
YES
- See "Before changing a control module." Before Changing a Control Module

NO
- The steps taken to rectify the fault were correct.