Merserybenze

In my 2010 c300 I have a problem. Sometimes on hot days when the car is sitting in the sun, I start the car and the AC won't blow cold (tried running it for several minutes).. But if I switch off car and restart car, AC is cold immediately. Strange. Anyone know why?

FuMMoD

I've encountered this too. It's extremely nerve wrecking because i expect the AC to blow ice cold fairly quick.

jpminou

Maybe a faulty temp sensor?

edgalang

Happened to me once. Scared me too, however I do not recall if restarting the car, or restarting the climate control fixed it. Luckily it hasn't happened again, although I wouldn't mind if it did so I can at least take it to the dealer before the warranty expires.

Until then, I'll consider it a fluke.

I do recall it being a hot day, and that by the time I noticed it, I was already flying through the freeway and wasn't able to stop the car. I usually have the vents pointed up, so I didn't notice the hot air until the cabin temperature became unbearable.

dudeitsmattx

That's crazy I have not herd of this before nor had it happen to me ever.

FuMMoD

looks like i might have a faulty sensor cause all i get is hot air out of my A/C. I didnt notice cause i usually ride with the windows down. It's like a sauna in there .... I got extended warranty through a 3rd party since I bought used. Hopefully its covered? They cover everything Mercedes would cover on a regular warranty.

FuMMoD

I just tried your trick and that works to getting the AC to blast cold air.

Merserybenze

Any idea where this is located and how easy it is to change?

jpminou

Not sure cause im new to mercedes maybe little search could help.

Im guessing maybe the box that change the air directions could stuck and when u turn off on ur car it work.

Merserybenze

had to restart my car 3 times today before the AC started blowing cold...it's getting worse..Anyone with AC system expertise pls help?

after searching this forum I see others have had a similar problem but I don't see a resolution anywhere. One potential solution I see talked about might be to replace the front SAM. Any opinions before I blow $400?

lemonstand

This happened to me once last summer. It freaked me out. I rode with it blowing heat for minutes before eventually it started blowing cold air. Hasn't happened since that one time last summer. <knock on wood>

LesF

I've had this too. Mostly when the car has been sitting in the heat. Same solution using a restart.

FuMMoD

I'm taking my 2011 to get the AC repaired. The dealer i bought it from covered it under warranty. It's like a hotbox in my car when i turn it on. It's unbearably hot.

Merserybenze

Oh dear- 3 restarts today in 90 deg heat!!! Knowing my luck it will work fine when MB looks at it. Any ideas?

FuMMoD

Received my w204 today after 2 days at the dealer. They said the freon levels were low. It was missing a couple of ounces and they filled it with DYE and have not located any leaks at all. Blowing ice cold now

Merserybenze

update.

The problem got more frequent. Daily the AC would blow hot air and take 5 mins or more to start blowing cold air. After much reading I tried some troubleshooting. I placed my windshield sun deflector on my dash every day - its sunny and 90's every day and I park outside. I haven't had the warm air issue once all week since doing this. I'm wondering is the problem then something to do with some type of temp sensor in the dash? Any thoughts?