W126 Climate Control Issues
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Newbie
Joined: Mar 2003
Posts: 12
Likes: 0
1985 500 SEL
W126 Climate Control Issues
I've recently acquired a 1985 500 SEL. I love the car, but . . .
the heater is all messed up. While the heat is fine on the low fan setting, when I set the fan to auto or high I end up getting cold air instead of hot from the vents. Also, the heater seems to be much more effective if I shut off the car and then restart it after the engine has warmed up. I recently had the climate control sensor between the sun visors replaced, but that didn't seem to affect this situation.
Does anyone have any suggestions?
the heater is all messed up. While the heat is fine on the low fan setting, when I set the fan to auto or high I end up getting cold air instead of hot from the vents. Also, the heater seems to be much more effective if I shut off the car and then restart it after the engine has warmed up. I recently had the climate control sensor between the sun visors replaced, but that didn't seem to affect this situation.
Does anyone have any suggestions?
MBWorld Fanatic!
Joined: Nov 2001
Posts: 2,332
Likes: 1
From: Bloomington, IN
1997 Toyota Tacoma 4x4
The problem may be a sticking monovalve, which is the valve that regulates coolant flow into the heater core. I haven't seen your particular problem before, so I can't say for sure.
Newbie
Joined: Feb 2004
Posts: 7
Likes: 0
From: Toledo
1985 500 SEL
We are also having probelms with our heater in our 85 500 SEL. The top vents seem to blow warm air, however it blows cold (and I mean cold) air in the back and also in the feet area. Could this also be a problem with the monovalve? Also any ideas of where we could get a good repair manual for the 85 500 SEL?
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MBWorld Fanatic!
Joined: Oct 2002
Posts: 1,560
Likes: 1
From: Columbia, SC
E300
We had a similar problem on your '85 300SD. It turned out to be the little motor that creates a vacuum to draw air from the rear-view mirror area through a small slotted opening. It draws this air in order to measure the temperature and makes adjustsments. The motor was located just behind the glovebox.
We had to order a small assembly, couldn't purchase the motor separately.
We had to order a small assembly, couldn't purchase the motor separately.
MBWorld Fanatic!
Joined: Oct 2002
Posts: 1,560
Likes: 1
From: Columbia, SC
E300
We had a similar problem on your '85 300SD. It turned out to be the little motor that creates a vacuum to draw air from the rear-view mirror area through a small slotted opening. It draws this air in order to measure the temperature and makes adjustsments. The motor was located just behind the glovebox.
We had to order a small assembly, couldn't purchase the motor separately.
We had to order a small assembly, couldn't purchase the motor separately.
Newbie
Joined: Mar 2004
Posts: 8
Likes: 0
From: Stockton, CA
1985 500 SEL
Your problem might be a simple fuse. Check your fuse box under the hood, and replace the blue fuse (25 amp). The problem I noticed with my 500 SEL was that the entire console buttons for the fan, the heater, etc just stopped working. So one day I checked all my fuses, replaced those which showed carbon burns and replaced them. Make sure you use needle nose plier and hold the fuse by the plastic sides with the tool. These simple fixes might solve your entire dilemma. If it doesn't, then check in with this forum again and/or call your benz mechanic and start gathering more info.
By the way, you can buy fuses either on eBay or at several of the online benz specialty parts stores. Try to have about 5 of the blue fuses for backups. Fuse kits generally give a lot of red and white fuses.
John
By the way, you can buy fuses either on eBay or at several of the online benz specialty parts stores. Try to have about 5 of the blue fuses for backups. Fuse kits generally give a lot of red and white fuses.
John
