Heater Problems
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Joined: Feb 2013
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1989 W124 200
Heater Problems
I have a 1989 200(W124)No heat comes out of the drivers footwell vent, although it does on the passengers. All other functions of the heating and cooling system are normal. The car does not have climate control. What could be the problem and hoe do I fix it?
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Joined: Nov 2002
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From: Massachusetts
2018 GLE350, 2014 G550, 2000 SL500, 1980 TR8, 1995 E320 Cabriolet
Does your car have independent temperature adjustments for drive and passenger sides? If so, your car has a "duo-valve" instead of the more common "mono-valve". As the same suggests, the duo-valve has two separate valves that facilitate independent control of hot coolant to the left and right sides of the heater core via two separate coolant loops. With the duo-valve systemyou could have a failure of one half of the duo-valve, a blockage in just one side of the heater core, or a failure of the circuit that controls the duo-valve.
If you car does not have the dual setup, when you say "no heat", do you mean no air flow or air flow that is cold?
If you mean no airflow, Plutoe is correct. The left and right heater outlets each have their own damper. These are connected together via a linkage behind the radio. If you take the plastic outlet covers off in the footwells, you should then be able to lie on your back in the footwell and see with a flashlight if the dampers are open or closed. The linkage may have broken, leaving one of them closed.
If you car does not have the dual setup, when you say "no heat", do you mean no air flow or air flow that is cold?
If you mean no airflow, Plutoe is correct. The left and right heater outlets each have their own damper. These are connected together via a linkage behind the radio. If you take the plastic outlet covers off in the footwells, you should then be able to lie on your back in the footwell and see with a flashlight if the dampers are open or closed. The linkage may have broken, leaving one of them closed.
