Hello everyone. I have. S class 2012. I live in Florida and I have been going back and forth with the ac doesn't work I thought it would be the compressor I bought an aftermarket one the mechanic put it in doesn't work I bought an used working ac compressor put it in still can't get it to work it won't turn on. I have xentry it keeps saing the the ground to compressor is bad. I took it to another mechanic and said the front sam is bad. But xentry is not saying the front sam is bad. But it looks like the compressor gets the power from the M1 connector at front sam and is not giving out any power. I've been spending money and not getting anywhere at the same time can't drive the car it's too hot. I have the diagram. Don't know where to start I don't know what else should I change the front sam? A little help please. Thank you.

 

I would go to the dealer.

 

Pull codes.

 

I would start with a better mechanic. Someone that knows these cars well.

 

if one says the SAM is bad and the power comes from the SAM - why is that first guy an idiot?

SAMs go wrong on Mercs
Faulty SAMs don't communicate correctly
Faulty SAMs on the S is less prevalent than other models
Its water ingress usually kills them

 

 

Fix the short.