I purchased a wrecked 2011 E350 coupe about 6 months ago, i fixed just about everything wrong with it except the Air conditioning. at first the compressor would not engage so i replaced it and filled freon but the compressor still didnt engage. I had my in laws check it out insisting they could fix and they messed up the whole wiring configuration and made their own running it directly to the fan, alternator for power and an aftermarket on/off switch under the dash. it worked at first but when i would switch it on, the air would blow cold but the fan was spinning way to fast. for obvious reasons< it busted after about a week. The Fan burnt out and the compressor started purging freon out of the top.I found some one who was able to help reconfigure the wires from the AC and fan to their original settings. He had an advanced diagnostic tool to and was able to get the compressor to engage but it kept turning off after a few seconds. Got a new fan in there working properly now, I replaced the compressor AGAIN, refiled the freon and replaced the pressure switch but i didnt help the issue. we found out that i didnt have a PremAir sensor on the radiator so i bought one and installed it hoping it might be the issue but still nothing. i turn on the car and press the AC button, the Compressor sounds like it engages for a second and then shuts off and the AC button light starts blinking. im thinking i might have a short or some kind of issue with the wiring but cant find a wiring diagram online anywhere. im here looking to see if anyone possibly has a wiring diagram for this car or if has had this problem before? Any suggestions?

 

Have someone pull fault codes using MB diagnostics.

 

Hi mate it sounds like the Blower regulator could be the problem here. Having the same trouble myself so I’ve just purchased one for £40 online you know the fan it’s self is working because it is trying to start but isn’t getting enough power. Good luck