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Hi, I could use some help diagnosing my 2012 W204 (early facelift, M271 engine)
The AC has not been blowing cold for a few months, which I have believed is due to lack of gas.
Yesterday I set out for a long trip with my car. Trying to overtake a slow caravan I heard a loud buzzing sound coming from the engine compartment when reaching upper RPM’s (sounded like just in front of me, initially thought from the fuse box). Stopped the car, everything fine. Tried a kickdown again, the same thing happened at upper RPM, but now also followed by a loud rattling, sounding like coming from the AC compressor. Limping the car home, the rattling came and went. When stopping/starting the rattle is dissappears, but appears again after some driving. Turned of heater and AC, now the AC won’t turn on again, button just blinks 3 times.
Due to holidays here, I haven’t got to do a OBD2 read. I was thinking of just ordering a new AC compressor, but before spending my cash, could it be something else that has failed?
Last edited by Thomasle87; Jun 7, 2025 at 11:20 AM.
I like checking for bulletins to see if there are any related to certain issues. Found something dealing with a noise coming from the AC. Not sure it addresses the AC not functioning, blinking AC light.
Usually in each section of the manuals they list the related bulletins. Can be helpful even if its a different year and model, can point you in the right direction.
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