Have Mercedes Questions? Ask a Mechanic for Answers ASAP
Hi my name is ***** ***** I will be happy to assist with this today.In some cases I may need more info to assist better.I apologize for any delay.
You are correct the compressor spins at all times.It has an internal clutch/plate that controls pressure and the ac operation.
What needs to be done from here is to have the fault codes read out of the heater/ac control assembly.There should be at least one code set that will help to diagnose and pinpoint this issue here.This has to be done with a fully compatible scan tool that can plug in and can communicate with all computers to see what codes are set.Once this is done the code is then diagnosed to locate and repair this fault then the code cleared out with the scan tool to allow the ac to resume.
On a Mercedes vehicle certain codes that can set due to faults can disable the ac from operating so the codes do need read out of the climate control head to locate this fault.
One common issue is the evaporater temp sensor sending a false signal needing replaced.I have seen this sensor cause this issue before several times.Even if you attempted to replace it to see if it resolves the fault the codes still need cleared out to allow the compressor to operate normally again.
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O.k.,that is great to hear you did check codes and have gone through these checks/testing above.With no codes set and the control unit says the ac compressor is at 100% this does sound like the compressor itself has failed internally.If there was a circuit fault or sensor fault a code would have set.I have seen the compressor fail in the past before causing this issue here with it needing replaced.
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