Last year I was getting my A/C chareged and my mechanic showed me how power was not moving through the contol unit. So I ordered another one from Peach Parts and slapped it in. Initially no problem and the A/C worked great. I live in Phoenix, so who needs heat! That's my problem this thing will be on A/C and it just flips out and starts pouring heat in the car. I have to shut it off, futz with the buttons, turn the A/C back on and then it starts to cooperate. That was......until about 4 weeks ago, now it won't do anything but blow hot air into the cabin, even the vent is hot!!!!!! Help!!!!!! I'm melting out here :-). Is it the contol head again? Any help is appreciated. Rick

Do a search on mono valve, it needs to be replaced.

How do I find this mono valve to replace it and when I look it up, we're talking $276, is that right?????

Not all MB's have the same climate control system. What year and model are you working on? Is it safe to assume that it is an MB?

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2001 SLK 320 six speed manual
2014 Porsche Cayenne six speed manual

Annoy a Liberal, Read the Constitution

I have a 1983 300SD Turbo Diesel, I should have stated that earlier :-)

could be the temp control wheel

I'm not familiar with the climate control in the 126 cars. Does it have a little square grille on the dash?

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2001 SLK 320 six speed manual
2014 Porsche Cayenne six speed manual

Annoy a Liberal, Read the Constitution

I removed the valve this morning and the rubber seal was torn. So the valve is indeed defective. I will get the replacement and f/u to give you an update when repairs are complete.

I replaced the valve and while the air seems to be more room temperature rather than blowing hot, the A/C will not go on.