Hello, I don't have a lot of time to spend looking thru all the pages to see if my problem has already been addressed, so sorry if I'm asking a question that's already been answered. But it's kind of important now that we're heading into summer, and I'd rather have an idea of what could be wrong before taking it in to the dealer. I have a 2011 C300 4Matic Sport edition, and suddenly my AC has started to only blow warm or slightly cool air no matter how long I leave it on. I always turn on and run the heater and AC with the auto feature, but I've tried turning it on with the AC button, the max cool button, nothing works. I usually end up turning it off, waiting a few minutes, then turning it back on and waiting a few minutes, then back off, etc. until it finally kicks in--which so far it eventually does, and then it does get nice and cold. So it doesn't seem like it's a recharge issue. Any ideas on what the problem could be?

 

It could still be low. There is a certain threshold that the A/C system needs to see before it shuts down, so it could be right on the fence. However it could be a bad compressor as well, you would need to have the car hooked up to a star machine and have the compressor output pressure tested. There is a small change the A/C push button isn't sending the signal either. Either way this problem will not be fixed without the proper scan tool and testing procedures. I recommend the dealer for that.

 

You might get better help in the correct forum, this is W205 (2014/15 on).

 

HVAC is HVAC. Refrigerant level is critical. You can't diagnose these systems without a full charge. There is a pressure, temperature switch at the base of the front condenser unit that shuts down the system to protect the compressor if refrigerant is low. Get the system re gassed!

 

Yes, well, I have no idea what "W" a C300 is, and couldn't find any way to determine it, so I took a stab at one.

 

I would have transferred you if it made any difference. You have a W204.

 

I have the same question on a 2011 C300 4 Magic. AC was in great working condition and suddenly started blowing cold air sometimes. Now it’s not blowing cold air at all. Tried resetting ac by simultaneously pressing defrost and recirculating buttons at the same time but the lights on those buttons did not start flashing.

 

I would check the refrigerant level. Sounds like a leak. Or the compressor went.