heater blows cold - sometimes
 

Hi,
Last year my heater started blowing cold air out of the right foot outlet (all others blew hot). During the next several weeks one outlet after another started blowing cold until I was shivering. Turning off the heater and then turning it back on would restore warm air, but only for a minute or so.
I had the cooling system flushed and that helped - for a while. Now winter is approaching and cold air is once again blowing out of the right foot well outlet.
My local MB mechanic says it could be any number of things and wants to charge me accordingly for trouble shooting it.
Any ideas?
Thanks.

´92 MB 190E 2.3

I have the same problem with my '85 500SEL!!! Does anyone know what's up here? One guy told me it was the mono valve, but before I go and have that fixed/replaced I'd like a couple of other opinions.

Thanks in advance to all you wonderful benz-iacs here and your generous assistence.

Back to the top for another try.

Mine Too
 

My car does that too, it is like it has a mind of it's own, it blows hot and cold, and sometimes when I take off from the stoplight it blows hot when it should be blowing cold, hmmm My S never did this.

Check this thread and also do a search under climate control or A/C. Lots of threads on this topic

http://www.peachparts.com/shopforum/showthread.php?threadid=77503

Thanks euron., I did that before I posted but nothing really applied. I should mention that I don´t have ac, just a plain ole heater so how complicated can this really be?

Crowzer

What do you mean by "you do not have A/C?"

1) Have A/C system installed but does not function?
2) No A/C System installed?

I am no expert on this, the advice that I can give you is from experience in fixing my A/C system. I was neck deep in thrying to figure the whole thing out and read a lot of threads on this.

Now, from my experience, if you have a mixture of cold and hot air blowing out of different vents is because there are problems with the accuators (?) these are like diagrpham cells taht operate on a vacuum system. Whent he diaphram dies, you can not control where the air is blowing from. Also, there one that controls the heat which is the Heater Valve. When this one went out on my, I had hot air coming out the side vents and the floor and only cold air coming out the center console vents.

Wgat you need to do is check the vacuum system of the climate control system to diagnose which vacuum valve is gone bad.

Also, a slight posibility is the that Push Button Control unit can be faulty but check the vaccum valves fist.

No ac system is installed. Not necessary in my neck of the woods.
What you´re saying makes sense, but why would the cold air not come out of random outlets instead of the fixed order (bottom right, top right, then left side, then defroster, right to left) that it does now? And why does turning the heater off and back on restore hot air (for a minute or so)?

The control panel is sliding levers, if that makes any difference.

c

crowzer - Can I assume your coolant level is good? Sometimes the simple soloutions are overlooked (esp on MB)
;)

Have same prob. 190e 1987 2.3 tried all recomended solutions.. still the same prob. Called Ken at The Benz Store in Atlanta 1 800 631 4170 He said he was puzzled for a while with these problems and finally found the problem....The reostat which is in the heater section . (requires a dash removal) was the culpret.it is an adjustable unit, but after replacing it, things got back to normal.....He sells nationwide and is helpful in a lot of Repair Problems.........Ask for a catalog........He sells alot or reman. items it saves some bucks sometimes.... Pete

what the shop said:
 

¨Poor radiator flow through¨
So they put a new one in and duly charged me an arm and a leg for it.
It seems to be working.
So far.

My heat issue (as in total lack thereof unless you turned off the car and started it again) was completely solved by replacing the monovalve.

Now I just need to learn how to fix the slider that opens/closes the driver side vents. The slider moves but nothing happens in terms of airflow.