tylfo35

Hello guys, oblivious newbie here, long time lurker, first time poster yada yada. I have a 2006 w203 c230 Sport 6 speed manual that I purchased a bit over a year ago and have put a bit over 10k on putting the mileage at 165k. When purchasing the car was told the AC would blow cold in the mornings no problem, but have issues in the afternoon. I took the car to a shop and spent around $1500 having the ac compressor and expansion valve replaced. AC still operated intermittently, sometimes the dead of night or first thing in the morning it would blow ice cold, but during the daytime it would rarely blow cold air. Was told by the mechanic it is an interior AC sensor in the dome light assembly reading zero degrees Celsius and that Mercedes charged $500 for the dome light assembly replacement and that it may or may not fix the problem. I went to a junk yard and pulled out a few dome lights to swap out, but none have worked so far. I'm so deep into this AC project financially and I would love to figure out what the hell is going on... why sometimes it works perfect, but most of the time it blows sweaty hot air. The AC also smells gross when it's turned on like mildew, the cabin air filter has been replaced recently. Could it be the AC Pressure Switch? I'm grasping at straws at this point. Thank you for any help and your time!

-Tyler

Plutoe

get a set of AC gauges and some experience with them and you are on your way to solving your issue. nothing in life is free

tylfo35

The problem doesn't seem to be the mechanical side of the system and me saying the pressure switch is a long shot IMO. It's pressurized, the condenser is fine, the expansion valve and compressor are brand new. The AC blows ice cold when it works, but other times it's as if the computer thinks the interior is too cold/freezing temperatures so it won't turn on the compressor. Sometimes the AC light in the center console will turn on by itself and cold air will seep from the vents, but I hear this is an automatic feature to help with moisture.

My brother has a set, we'll make sure the system is still pressurized, but since the interior dome light sensor reads zero degrees even when you blow air into it, we might need to track down that problem as well! Thanks for all your help and if anyone else has had a similar issue I'd love to hear!