Automatic Climate Control, ACC

B2375





Heat exchanger solenoid. Short to B+
Heat exchanger solenoid. Open circuit/short to ground

Fault symptoms
The perceived cabin temperature is too high or too low compared to the set temperature.

Conditions
The following conditions apply:
- A short to B+ is indicated when the output for the heat exchanger solenoid is activated and the voltage on pin 24 exceeds 6 V.
- A short to ground is indicated when the output for the circulation pump is not activated and the voltage on pin 24 exceeds 6 V.
- Measured every 440 ms and 5 consecutive measurements are required to set a diagnostic trouble code.
- The diagnostic trouble code is deleted after the ignition has been turned on 20 times if the fault conditions have not been fulfilled.
- When the diagnostic trouble code has been set the output is switched off.





Diagnostic procedure

1. Checking the power supply.
- Turn the ignition key to ON





- Unplug connector: Solenoid, heat exchanger (581).





- Connect a test lamp between pin I on the female connector and a reliable ground point.





- The test lamp should light.

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





2. Checking the ground lead
- Connect a test lamp between pins 1 and 2 on the female connector.





- Contact the ACC.





- Activate: Solenoid (ON)
- The test lamp should be off and light up when activated by the diagnostics tool.

Is the function correct?
YES
- Replace Solenoid, heat exchanger.
- 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.