Style_Front

What the funk?! What's the fix?

Rallyboy383

It is probably your heater control valve which is located beneath the hood under the cowl. Do a search and you will find a write up on how to replace it. Hope this points you in the right direction.

Hulk

https://mbworld.org/forums/e-class-w...rol-valve.html

I am in the process of doing it also, part was 48$ at the dealership

berti_00

100% your Heater control valve... had the same exact issue were it drove me nuts. Replaced that and it works perfect

Style_Front

Thanks guys I'll replace it. I tried searching "rear heat/er" and got all kinds of non sense. Thank you sir's

cwmateiuc

They're most likely right, but also check your outside air temperature sensor. Make sure it's reading correctly.

Denroll

Do yourself a favor and get a spring-style hose clamp pliers. There is one hose you have to remove that has one of these. When I did mine, the parts you need to grab in order to loosen it were facing towards the fire wall with no room to grab it. That one clamp took me 30 minutes to remove. Now I have these pliers and those things take seconds to remove now.

baldmike73

had the same issue - luckily warranty covered - was the valve too - was a pain to replace if i recall

Bramage

I have had the issue for 2 years. Have had the parts for over a year.. I just bought the window cowling so I can change that at the same time. Im a procratin ator

Hulk

Want to add to the DIY, remove the wiper motor as well , makes all the difference, only 3 bolts and gives you much more room. Unfortunately I still have warm air on driver side , I'm hoping it's missing freon and not the drivers side sam