Mechanics

NO HEAT ON BOTH SIDES

1984 Mercedes Benz 300sd

Heater problem
1984 Mercedes Benz 300sd 135000 miles

Some mornings I have heat on the passenger side and not on the drivers side. Other days its the opposite. This car does not have climate control for either side. Air blows on both sides but one is cool and the other hot. I had everything apart and cannot find any doors that are not operating properly. The puzzling thing is why does have hot on one side and not the other and the next day it will be reversed.
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Seweavers
October 19, 2010.



The control valve is working. When we drive the car there is no heat. When we shut the car off, wait a few seconds and turn the key on (we do not start the engine) there is heat. Once the car is started, it goes back to cool.

Tiny
Seweavers
Nov 1, 2010.
You failed to mention that the circulation pump was working. It is starting to sound like a plugged heater core, you can remove the line from a heater control valve and use your garden hose and try to blow out the heater core to see if you've got a circulation

Dr Loot
Nov 1, 2010.
I do not have the circulation pump as shown in the picture. This pump is on my 300d that we have but not the 300sd. I can get very hot air when the engine is off.
We are getting circulation but in my opinion it may be inadequate. I beileve ther is another type of valve under the valve at the firewall. It does NOT have any wires going to it but the hoses do. Will try to bypass this to see if flow increases.
I have an 83 and 84 sd and 1 84 300d and 2 85 300sd.

Tiny
Seweavers
Nov 2, 2010.
That would change everything if it is a 300d. I have one of those in my storage lot, let me go take a look at it and I will get back to you

Dr Loot
Nov 2, 2010.
This is on a 300sd. One of the photos you had posted was not like the 300sd, it was like the 300d.

Tiny
Seweavers
Nov 2, 2010.
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