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I went to my local Mercedes dealership today to try and buy an airmatic relay as my compressor no longer engages when I start the car. Car is showing "Too Low Pull Over" Red message. They asked me what slot the airmatic relay is and I had no clue as they are the experts. I tried googling what slot it could be as it seemed like a simple question. But I was unable to find an answer after 15min of searching on my phone at the dealership.
But when the dealership expert showed me their parts screen is was like Slot J,K,M ect (Im not sure if those are the real letters, they are just an example).
Does anyone know which slot is for the Airmatic Relay? They advised to change the fuse at the same time, so I will do that once I figure out the correct slot for the Airmatic relay.
Here to help with... you're seeking to replace your compressor RELAY - That is unusual item.
Did you find your air compressor is not receiving power ??
Often the compressor internal thermofuse protection goes open ie. defective... replace that.
The next step is to identify what part caused the previous compressor to get over heated.
Identify your AirMatic issue:
leaky hose connection
rusted valve block
leaky air spring bag
rusted height sensors
Put on your detective hat.
Yes i have a brand new compressor in the mail. Should arrive tomorrow. I also have both rear air bags and both front shock & strut by Arnott [all sides]. Since my vehicle is now 15 years old with all factory parts, I was just planning to change everything airmatic related since they are mostly end of life. The relay seems like the easiest to change and replace so I was going to start there to see if I can actually get the car to rise up and drive it to my mechanic.
3/4 sides sags after a couple days if left out in the cold. The compressor not activating was the final nail in the coffin for me to get her looked at.
If you have power to the airmatic system it won’t be a relay.
The problem is there is no power to the airmatic when I start the car. Compressor does not engage (I dont hear it when i start the car with the door open) , and the red message just displays on the dash. Car does not rise up.
The problem is there is no power to the airmatic when I start the car. Compressor does not engage (I dont hear it when i start the car with the door) , and the red message just displays on the dash. Car does not rise up.
Gotcha. Sorry, I misunderstood your issue. I would definitely check that relay next to the tank in the trunk. In my short tenure with my E63 it was located in the rear. I believe there is another one on the rear SAM, but I could be wrong. I’ll try and ask one of my friends at Mercedes if he can pull up any info on it. What year is your Benz?
Gotcha. Sorry, I misunderstood your issue. I would definitely check that relay next to the tank in the trunk. In my short tenure with my E63 it was located in the rear. I believe there is another one on the rear SAM, but I could be wrong. I’ll try and ask one of my friends at Mercedes if he can pull up any info on it. What year is your Benz?
Just went through this on my 2011 E550. Compressor relay is on the left side of the trunk right behind the reservoir tank. Pull the cover, and you can't miss it.
You may also have a blown fuse in the pre-fuse box on the passenger side strut tower. If that's blown, you'll need a whole new pre-fuse box.
You may have already discovered this, but some compressors come with the relay.
Just went through this on my 2011 E550. Compressor relay is on the left side of the trunk right behind the reservoir tank. Pull the cover, and you can't miss it.
You may also have a blown fuse in the pre-fuse box on the passenger side strut tower. If that's blown, you'll need a whole new pre-fuse box.
You may have already discovered this, but some compressors come with the relay.
I couldn't find anything indicating a fuse in a fuse block fast enough that I didn't feel it wouldn't be faster to just check them all real fast. The pre-fuse box fuse is internal and non-serviceable. I pulled the box and split it, and was able to very clearly verify that the fuse was blown, but again, not serviceable. New one is sitting by the door, and I'll be installing it after breakfast this morning.
Tip: It was pretty clear that it was blown BEFORE I split the box, and if I had had enough information, I could have moved a little quicker. When you pull the box, there's a three prong plug (as opposed to a ring terminal), and one of the pins (big huge wide tongue of a thing) that it mates with in the pre-fuse block was loose. That's because it was held in place solely by a plastic pin rather than that and the metal body of the blown fuse. Bottom-most pin as I recall.
Instead of opening the pre-fuse box, it may be easier and quicker to check if you have power at the compressor relay socket, next to the compressed air reservoir.
Remove the relay and check voltage between terminal 30 in the socket (from the pre-fuse) and ground with a multimeter. From memory, that should be always energised, so no need to have the ignition on.
If you have 0V then I would check the pre-fuse.
If you get 12V, then you could use a jumper cable with a 20 or 30A fuse between terminals 30 and 87 in the socket to see if you can run the compressor.
If you cannot hear the compressor running, then the compressor is dead and needs to be replaced (most likely) or the short cable between the relay and the compressor is damaged (very unlikely) or the brown ground cable from the compressor to the ground point is damaged (very unlikely).
If you can hear the compressor running, then you could remove the outlet hose from the compressor outlet to see if you feel any airflow and pressure. If you can feel air blowing but can block the airflow with your finger, then it means that the compressor is moving air but it is not building enough pressure and needs to be replaced or refurbished.
If you cannot block the airflow, the compressor could be considered healthy (ideally you would want to measure with a pressure gauge to see if it reaches around 180 psi).
At this point, the issue would be likely to be associated with the control circuit, including the relay itself.
2 months later and my car is fully fixed (I loafted for a month). I had to in the end replace all 2 front bag and struts as well as both rear bags. I also replaced the aging compressor as well as the airmatic relay. The hardest part was finding the relay as the Mercedes Dealership said the OEM relay was discontinued by Mercedes. The Dealer was surprised as my 2011 is only 15 years old and not that old in his words.
This would have been great information when I was searching for a relay replacement lol. I wonder why the Mercedes Tech didnt just sell me once of these relays instead when they said the relay was discontinued. O well I guess the information is here for whoever needs it next.
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