No heat on driver's side

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HASH - 25 Apr 2006 13:48 GMT

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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trader4@optonline.net - 25 Apr 2006 17:19 GMT

> 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?

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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Jens - 27 Apr 2006 17:00 GMT

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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trader4@optonline.net - 27 Apr 2006 17:46 GMT

> 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
[quoted text clipped - 4 lines]
> In my 1987 190E, the knobs and flaps are connected by a mechanical
> cable. This should be easy to troubleshoot (but difficult to access).

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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Richard Sexton - 25 Apr 2006 20:54 GMT

>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?

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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