B Marques

On my 2011 GL 450 I noticed all 4 corners were down and figured the compressor was the culprit. I ordered an arnott one and nothing. The compressor is not getting power and not kicking on. I checked all fuses and the seem to be okay. Any ideas??? I just checked old compressor with a battery and it still works.

alx

Compressor relay would be my next guess

B Marques

I believe the relay is the 3rd green one in the fuse box in the engine bay and I switched it with the 1st green one and still nothing.

B Marques

Can someone confirm which fuse and relay control the Airmatic system

WilliamPryor

B Marques... I am having the same issue right now and have another thread open on this. My GL is at my mechanics right now, and he said the compressor is not getting power for some reason. I replaced the compressor relay and checked the two 40 amp fuses and nothing happens when I crank the truck. The compressor will not come on and he nor I can figure out why. I will post a picture of the relay in a second...

WilliamPryor

WilliamPryor

The two fuses for the compressor are the two orange fuses, running back to front above the circled compressor relay.

alx

If relay/ fuses and compressor are ok you have airmatic hard faults stored at which point the airmatic controller might disable the compressor to protect it. Car needs to be read with star/ das and and if hard faults (F) are stored the controller needs to be reset. You need to clear the underlying problem or the compressor will be disabled again.- usually excessive pressure loss but not enough to overheat the compressor (in which case console message "compressor cooling down" is displayed).

B Marques

Is there an ecu for Airmatic under driver side feet? I have an independent mechanic saying that ecu needs to be replaced. I think he may be ripping me off.

alx

I have never seen an airmatic module go bad. It is possible, but normally it will fail communicating with star/ das at which point it is obviously the culprit. My guess is just needs to be reset/ faults erased. If module is clean but still no power to compressor (and fuses/relay/compressor are good) then the module might be suspect.

WilliamPryor

alx... I am calling my mechanic today to see if he has the proper diagnostic tool (star/das) to check for these possible hard faults. Thanks for the information! If he doesn't have the right tool, then I am going to call another independent mechanic in town to see if they have it. If they don't, then I will have it towed to dealer 100 miles away. I will keep everyone updated on what I find out. Thanks again alx!

WilliamPryor

Quick Update.... My mechanic did have the the proper tools and with the help of the MB Tech line he determined that the fuse box was burnt up. He said the tech told him he had seen this before when people would switch around the relays, like I did... I feel like an idiot! Anyway, I went and picked up the GL this morning and after driving for a bit I noticed that the back passenger side was sagging. It would come up some, but not inflate all the way. I could hear air wooshing out of it, when I stood back by the rear of the car. Everything else seemed fine on the car. Air compressor came right on, but it would not air up the rear passenger side all the way. So, I took it back by the mechanic to have him look at it. I am hoping that all it is the rear passenger side airbag. Thanks for all the help I have received on here!
P.S. Anyone want to buy a 2008 GL 450 with 47,000 miles on it?