treiberg

My 2005 C230K has a problem where the AC just stops working, all the fans shut down, the 'Auto' button light goes off...all without me touching anything. I press the Auto button a few times, nothing may happen for a few minutes, then it just decides to come back on again. Delaer replaced alternator about a month ago thinking that it was a power supply problem that was messing the with control module. Seems to be getting worse...happened about 10 times the other day (in the past it might happen once or twice per week). Car is just about to run out of warranty period, but would like to pass on any info to my dealer to help him fix it before it runs out.

I've seen some posts that others have had similar problems. Anybody out there been able to resolve it? Thanks for any info you can provide!!

Musikmann

As long as you are having your dealer doing warranty work, it will be documented on the MB system so that is good. In other words, even if it takes them beyond the warranty period to isolate the problem you should be covered. And if they give you grief about it, you have some ammunition to fight with. Good luck.

naijabenz

Mine started about a month ago. For a sec i thought it was low refrigerant but i was quickly reminded that if that is the case then the compressor goes off but the fan and everything still works which is not the case. Like you, the whole thing just shuts off. I noticed that it only did that in "auto" because the last time it did that, I pushed the auto button and nothing happened and then i turned on the fan manually and the fan came on. I was told by my mechanic that the AC control Module (with the auto buttons and AC control knobs) might be bad. Problem is they have to 'see' it acting bad before they can call the warranty folks. I am not sure how to show demonstrate the problem to the mechanic because it starts working normally in a couple of minutes. Please update this forum with whatever your solution is

dnlow

I am surprised that the dealer did not know right away what the problem was from a previous post. This is a fairly common problem. It is most likely a issue of two problems. You will need to have the blower regulator and the blower motor replaced. I had the same problem and the dealer first replaced the blower regulator which did not fix the problem and then they replaced the blower motor and that fixed the problem. I have been trouble free for about 18 months now. I am almost certain that this is the problem for both posters. If you have any more questions just ask.

EV0LVE

i had the same problem, thank god it was replaced under warranty, but it's the control module for the ac, bring it back to the dealer, i wish i can find the work order/invoice for it, but I remember it being a control module.

trisonics

I noticed the same problem on my car about two weeks back. Since then it happened 3 or 4 times. Going by the history of my car, I know for sure that after another two weeks of phoenix summer it is going to completely break down. But it does not bother me as I going to trade it in for a 3 series (with warranty) in few hrs.

whalebird

Go to the benz dealer, next trade for BMW, next flame all over the net evrything Benz. This time next year you'll be in a big Audi. I'm sorry if I offend, but this is not even close to being a technical forum. I would love to find good technical discussion about MB

venturaII

Let me know when you find it.

treiberg

Dealer replaced the control unit (the module that has the knobs and pushbuttons on it) a couple of weeks ago and haven't seen problem since, so hopefully that was it. Luckily, it was under warranty, so i do not know how much it would cost otherwise.

Side story...dealer also replaced some weak trunk door springs since door would not open all the way without some help. In the process, they dented the rear body panel on one side - they must have let the spring pop loose and it created a nice dent, pushed out from the inside. They now have to repair (repaint) the whole left rear quarter. Kind of bummed because it had nice factory paint - my thinking that repainted it will never be the same as original paint. Really no other way to fix it, though. They finally decided to give me a loaner vehicle while they fix mine.

RDVT4ME

You might be OK on the paint. My car was sideswiped by a hit and run driver and they painted the drivers side rear door and fender and it is a perfect match. Paint work done by fletcher jones MB in socal.

Sorry to hear the dealer messed up your paint.

viksc230

same problem here.......AC&AUTO turns off by itself(friking anoying as hell) intermitantly. I was hoping it was the regulator or cabin temp sensor or blower. I have noticed on a few occasions with ac on hot air comming out for a few seconds after the ac had been blowing cold for over 10 min. This makes me suspect the cabin tem sensor.....Anybody else w this issue please post your experience and resolution.

Glyn M Ruck

There are numerous threads running at the moment with similar problems. These HVAC systems are complex and many things can cause what people describe.

But I reiterate. You cannot diagnose an aircon problem on a Benz without first checking that you have refrigerant pressure on spec. If the pressure is low the pressure switch will shut down the unit to protect the compressor. I see rude comments about this not being a technical forum - That is BS. We have good technical people on this forum but Benz have changed the HVAC system in minor ways so often that it makes virtual diagnosis damn difficult.

Check your refrigerant pressure & then let's take it from there.

LILBENZ230

Oh *$&#*#.

My car did this twice two weeks ago. I told you about that in a PM, Glyn. It hasn't happened again so I'm not going to stress over it - yet.

RDVT4ME

I've had this problem too. Happens mainly when it is very hot out and is extremely random. I've had it to the dealer twice for the problem and they can never reproduce it. It may happen a couple times today and then not again for weeks. Very frustraiting when you can't reproduce the issue for the tech to fix.