AC not working and engine fan is loud
Thread Starter
Newbie
Joined: Apr 2025
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E350 W212
AC not working and engine fan is loud
Some context, I left the car for 2 weeks while on a trip, came back turned it on and the engine fan sounds like a jet engine (didn't sound like this before) and the AC won't turn on. Any ideas please help
Out Of Control!!
Joined: Apr 2019
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From: Silicon Valley
W212 MY'14 M276-3.5NA @75kMi
SUPERSONIC FAN
Usually this is the failed A/C pressure sensor that needs replacement or the A/C circuit leaked below minimum.
Confirm refrigerant pressure readings with OBD scanner or using an old-school "A/C gauge-set".
Don't bother dealing with the fan itself. It's remotely controlled by ECU.
Keep the battery from getting drained. Disconnect as needed...
Last edited by CaliBenzDriver; Apr 2, 2025 at 05:08 PM.
MBWorld Fanatic!
Joined: Oct 2010
Posts: 5,141
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From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
High screaming fan means the car thinks AC pressure uis too high. This, of course, means either the pressure sensor is bad, or you actually have high pressure in the A/C system.
Years ago, when this happened to me, I first thought charge is low, but adding refrigerant made it worse. I then let some out and it got fixed.
I may also have had bad sensor, but I did not replace it, just let some charge out.
Years ago, when this happened to me, I first thought charge is low, but adding refrigerant made it worse. I then let some out and it got fixed.
I may also have had bad sensor, but I did not replace it, just let some charge out.
