No heat on driver's side

I have a 190e 1992 and recently the heating on the drivers side stopped working. It only works intermitantly and does not heat up to hot at all. I have checked the vacuum and changed the valve near the wiper
motor but it's still cold.
The passenger side works great? Can any one help please?
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HASH wrote:

If you have heat on one side, why did you change the valve? The valve only controls water flow into the heater core. If heat is coming out on one side, it's not the valve.
There should be an air flap that controls air flow coming out of the lower openings. Not sure if there are 2 of them or how they are set up on that particular model, but if there is one for each side, sounds like the flap on that side is not moving correctly. You'll need to be able to see it and find out if the vacuum actuator is moving it. If not, could be a bad actuator, stuck flap, loose line, etc.
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Right, if any of the two heat control knobs are not in fully cold position, the vacuum valve opens and provides flow to the common heater core. Each heat control knob then controls a flap, which mixes hot air from the heater core with cold fresh (or recirculated) air according to the position of the control knob.
In my 1987 190E, the knobs and flaps are connected by a mechanical cable. This should be easy to troubleshoot (but difficult to access).
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Jens wrote:

Good point on the cable control for the flap. I was thinking of my car, which uses vacuum actuators. If it's a cable, it will be a whole lot easier to diagnose.
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I'm not familair with 190 heat, is it the same as 300Sd heat - a flap opens in the drivers side footwell?
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