Mercedes-Benz W163 A/C compressor does not run
ML 270 CDIML 270ML 400 CDI
The W163 A/C compressor does not run, what is the most common cause?
Often the fault is in the compressor's magnetic clutch: the coil, the clutch air gap or the clutch plate. Alternatively, the fault can be in the control, which does not give the compressor the command. First measure the clutch current and the A/C sensors.
How does a magnetic clutch coil fault affect the W163 A/C?
If the coil winding is partly short-circuited, the clutch draws too much current. The control unit then cuts off the compressor to protect itself, and the A/C does not start. Fault code B1105 has been seen.
Can the magnetic clutch air gap or clutch plate prevent the compressor from working?
Yes. Too large an air gap can prevent the clutch from engaging, especially with a warm engine. If the clutch plate is missing, the compressor may run, but the A/C does not cool; in that case fault code B1108 has been seen.
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