intermittent heater function - PeachParts Mercedes-Benz Forum

last123 · #1 12-30-2002, 10:41 AM

I searched the archives for solutions to my heater problem. The heater in my '85 300D is only working about half the time, and it seems to have been giving me problems since my vaccuum pump failed. I replaced the pump, but it still doesn't work properly. Sometimes I turn it on and it works great. Sometimes it blows, but maybe just barely warm if at all warmer than the outside air. According to some threads I found, I'll need to purchase a "monoblock repair kit" for a fix. Does this sound right? The abnormally functioning heater doesn't bother me too much - I can always wear a coat and gloves. But I'm getting some really harsh noises coming from my passenger seat, when occupied, on those cold mornings.

last123 · #2 12-30-2002, 02:14 PM

Right... mono-something. So the monovalve repair insert is the key? What is that? Is it difficult to install?
Regarding the noise, I think I'd still be able to hear her from the back seat. Perhaps I'll have to really crank up the Morning Edition until I get the heater fixed.

last123 · #3 12-30-2002, 05:24 PM

Thanks Bribenz. I searched more posts, this time looking for "monovalve" and such instead of just "heat problems" or whatever. I located it on my car and also pulled the glove compartment to look at the foam hose that comes from the temp. sensor. It looks to be in good condition so I'll go right to the monovalve.
As always, I appreciate the fine help from this board.