A/C Compressor cutting out
Thread Starter
Super Member
Joined: Jan 2007
Posts: 622
Likes: 202
From: CA
11 ML550, 95 Supra TT, 14 Audi S4
A/C Compressor cutting out
Has anybody ever found a solution for the A/C compressor shutting down for no apparent reason? At ~150K miles, the original compressor failed on my 08 GL and was replaced by the dealer. It worked fine for the rest of that summer, but the following summer, the compressor would kick off at times especially on 100F+ days leaving the system blowing warm air. Turning the system off and on repeatedly or toggling the A/C button usually gets the compressor to reengage, but it often takes some time and many tries. It has started doing it more often in the last year or two, yesterday on a 75F day. When it works, the system works well although I usually toggle the fan speed back on hot days because running it in "max A/C" mode seems to almost guarantee a problem. The dealer has evacuated/refilled the system and flashed the control unit, neither of which solved or improved the problem. I've seen others complain of similar problems, but haven't seen a solution. Anyone found one?
Junior Member
Joined: May 2007
Posts: 34
Likes: 11
2009 gl320
I did install a diode last year and it seems to help. It has not been warm enough yet this year to run AC.
https://mbworld.org/forums/gl-class-...-9006-a-2.html
https://mbworld.org/forums/gl-class-...-9006-a-2.html
Thread Starter
Super Member
Joined: Jan 2007
Posts: 622
Likes: 202
From: CA
11 ML550, 95 Supra TT, 14 Audi S4
After getting an icarsoft, I found I have the 9006 error with a MB compressor. Time to add a diode. Also found I have a bad RF speed sensor, which would explain the low speed jerkiness I experienced the other day. Must be contagious since I had the same problem on another car recently. Ironically, the part for the other car (a Toyota) is about 2.5X the cost of the MB sensor, although the Toyota part wasn't bad (the sensor ring got fouled with grease and debris).
Thread Starter
Super Member
Joined: Jan 2007
Posts: 622
Likes: 202
From: CA
11 ML550, 95 Supra TT, 14 Audi S4
The diode seems to have done the trick. It hasn't been really hot yet, but the compressor has worked 100% of the time after installing it even when I've dropped the temperature enough to make the system go to higher fan speeds which usually made it kick off before. I'm adding pictures to the thread referenced above because the wire location looks significantly different on a gas engine.
Junior Member
Joined: Aug 2021
Posts: 45
Likes: 3
2009 GL320 Bluetec
@EWT , I have a very similar situation. The A/C compressor on my 2009 GL320 with 140,000 miles, seems to kick on and off intermittently. Since it's been a year, has the diode fix continued working? Normally, I would just replace the compressor, but the Denso and MB OEM compressors are on national backorder.
