jagata

My 2004 e500 has hot air not blowing but emitting out from the center vents even with the climate controls all off. It's been pretty warm here in Cali and going to reach near 90 degrees this weekend, anyone know what I can do?

Barry45RPM

The center vents do pass thru outside air to the cabin. Is your A/C compressor on/working?

jagata

Yes when the a/c is on it blows cold, however when the system is completely turned off then you can still feel hot air emit in.

Barry45RPM

Thats how it works. It always passes outside air into the cabin. If its hot out the air will be warm coming thru the vents A/C compressor should always be on.

jagata

Sure , but it shouldn't bring all the hot air from the engine in. This is not my first w211 so I can tell that something is not right.

E500 Benzo

the heater core change-over valve is most likely stuck open (allowing hot engine coolant to flow into the heater core and heat up the incoming air). when you turn on the AC, the cold air produced overpowers the heat so it seems like nothing is wrong again.

(check out #30 in the attached photo - its MB part# A 211 832 00 84 and was replaced with the updated part# A 211 832 05 84)

if my memory serves me correctly, there might even be a DTB about it somewhere

jagata

Now that makes sense, thanks for taking the time. I'll look into that, car says it's 95 degrees out today.

spinn

did you get it fixed? I seem to have the opposite problem. all I get is cold air, even if I crank up the temp to 80 degrees. wondering if that heater valve may have anything to do with it.