AC System Replacement
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Newbie
Joined: May 2025
Posts: 2
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W166 ML350 Bluetec
AC System Replacement
Hey all,
I have a 2012 ML350 bluetec. My wife was driving it and the AC went out. She took it to Firestone because we had them recharge it a couple years ago. They started doing some diagnostic and determined that the compressor had a "catastrophic failure."
Their quote was $6,000 to replace the compressor, drier, and evap coil.
I didn't ask why they wanted to do the evap coil because I wasn't there, but I assume it's because they're worried about stuff in the system due to the compressor failure.
My question is, is if the compressor did fail like that and basically grenaded in the system, is it dumb to just replace the drier and the compressor, have the system flushed and charged, and not do the evap coil?
I am fine to do the compressor and drier myself, but I am not taking out a dash.
I have a 2012 ML350 bluetec. My wife was driving it and the AC went out. She took it to Firestone because we had them recharge it a couple years ago. They started doing some diagnostic and determined that the compressor had a "catastrophic failure."
Their quote was $6,000 to replace the compressor, drier, and evap coil.
I didn't ask why they wanted to do the evap coil because I wasn't there, but I assume it's because they're worried about stuff in the system due to the compressor failure.
My question is, is if the compressor did fail like that and basically grenaded in the system, is it dumb to just replace the drier and the compressor, have the system flushed and charged, and not do the evap coil?
I am fine to do the compressor and drier myself, but I am not taking out a dash.
Member
Joined: Oct 2023
Posts: 117
Likes: 45
From: Buchanan, SK CANADA
2013 ML350 Bluetec
I'm no AC authority so consider that this advice may be worth exactly what it is costing you. I have done what you are facing a couple of times. I would NOT replace the evap coil - that's a ton of work. I would replace the compressor, condenser and drier. I would back flush the entire system a few times with some kind of fluid. I'm too cheap to use anything fancy - I think the last one I did I used Varsol or maybe gun cleaner. After that I would blow it out backwards before evacuating it. But like I said, I'm no authority - just a sometimes shady, shade tree wrench puller with a lot of gray hair.
(on edit)
I don't know what MB uses for an evaporative orifice - I come from the Ford world where the older systems had a separate orifice that was easy to replace. The newer systems have a fancier (ie. more expensive) orifice with a fancy new name that I don't remember but its still a separate component. Whatever MB does, that orifice is pretty much the most important part of the entire system and it absolutely has to be replaced. If the kraut engineers somehow build that into the evap coil then you may actually need to change the coil as well.
(on edit)
I don't know what MB uses for an evaporative orifice - I come from the Ford world where the older systems had a separate orifice that was easy to replace. The newer systems have a fancier (ie. more expensive) orifice with a fancy new name that I don't remember but its still a separate component. Whatever MB does, that orifice is pretty much the most important part of the entire system and it absolutely has to be replaced. If the kraut engineers somehow build that into the evap coil then you may actually need to change the coil as well.
Last edited by bobofthenorth; May 24, 2025 at 06:04 PM.
