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A/C Struggling in Local Driving – 2009 C300 Sport (109k miles)
Recently, with the hotter temps here in the Northeast, I’ve noticed that the air conditioning in my 2009 C300 4MATIC Sport (109k miles) has been non-existent during local driving. It takes several minutes before I get any cold air, and that’s only if I’m on the move — once I hit the highway, the A/C seems to work just fine. But for short local trips (which are the majority of my drives), it struggles to blow anything remotely cool.
Since this is mainly my grocery getter, this has become a noticeable issue.
Here’s what’s been done recently:
OEM Drive Belt Kit installed
Replaced all spark plugs
Replaced two engine coils
Tried recharging with AC Pro R-134a, but as soon as I connected the gauge, it showed 56+ PSI in the red, so I didn’t proceed with adding any refrigerant.
Based on the symptoms and high pressure reading, I’m wondering if:
The compressor is weak or failing?
There’s a clog/blockage in the system?
Or possibly an issue with the condenser fan not kicking in at low speeds?
I’m not sure where to start diagnosing beyond this and would appreciate any tips on what to check first before going down the rabbit hole of part replacements.
Has anyone dealt with similar symptoms? Any common A/C issues with the W204 chassis I should be aware of?
I recently worked on my ac that was blowing hot air. In the end I put in around 1/2 can of refrigerant and it works perfectly now. My Foxwell scanner came in very handy to see what was exactly going on so I didnt mess it up further. Heres the thread: https://mbworld.org/forums/mercedes-...ctions-do.html
I would hook up a scanner and see what everything is doing. Can see if the compressor is turning on, see the pressure, evaporator temp.
On mine when I hooked up the gauge to the low pressure it was reading low, then when I turned the ac on it dropped even lower. With the gauge connected does the pressure change with the ac on?
Just out of curiosity did you try cleaning the AC system? The W204 is older now and if it has not been done along with a filter change it could block the airflow. Same applies with HVAC in your home.
I use this in all my cars 1 time a year or after filter changes. Whatever comes first.
I looked up "AC Pro-R-134a" and all of the various versions im seeing say they contain a Leak sealer in the description. When I added refrigerant to mine I used just R134a refrigerant no sealer. In the MB manual it mentions not using a sealant.
Then again with the low pressure port reading 56 psi I wouldnt add any more refrigerant. when I added refrigerant to mine I stopped when the gauge was reading around 36 psi. My scanner was showing 9-12 Bar when running depending on the climate control settings.
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Slideshow: A one-of-one U.S.-spec Mercedes-Benz SLR McLaren Roadster became even rarer after a factory-backed transformation at McLaren's headquarters.
