Weird problem with heating system
01-29-2008, 04:30 PM
#1
Junior Member
Thread Starter
Join Date: Nov 2007
Location: Shenandoah Valley, Virginia
Posts: 15
Likes: 0
Received 3 Likes
on
3 Posts
1990 300se, 1980 450sl
Weird problem with heating system
Before posting, I did a search and did not find the same problem.
With my 1990 300se, you can set the heat on "econo" and it seems to work fine, including when you change the temp setting up and down. Here's the problem.
When you change from the "econo" to say "defrost" it starts to blow cold air, if you go back to "econo" it blows cold air. If you turn off the car and turn it back on, it works correctly again. If you turn the car off, set it on defrost, turn the car back on, it blows hot air. like it should.
It appears by turning the car off and back on it resets something, any ideas??
Paul Waddell
1990 300se
Front Royal, VA
With my 1990 300se, you can set the heat on "econo" and it seems to work fine, including when you change the temp setting up and down. Here's the problem.
When you change from the "econo" to say "defrost" it starts to blow cold air, if you go back to "econo" it blows cold air. If you turn off the car and turn it back on, it works correctly again. If you turn the car off, set it on defrost, turn the car back on, it blows hot air. like it should.
It appears by turning the car off and back on it resets something, any ideas??
Paul Waddell
1990 300se
Front Royal, VA
02-01-2008, 08:24 PM
#2
MBWorld Fanatic!
Its probably your monovalve. Do a search. I found a great pictorial on how to replace it. I was able to do so in a dark garage with just a screw driver (simple fix).
