Heating problem

I own a 1987 190E 16v and the heater does not work at all. I searched for monovalve on the site, but I don't think the valve described in the threads is the valve used on my car. My valve doesn't have an electrical connection. It has a vaccuum which connects to the top of a black bulb. The vaccuum is what opens and closes the valve. The part that confuses me is that the valve is constantly open, so I should constantly be getting heat. This is not the case. I get forced air through the vents, but it is only outside air. Brrrrrrr. I checked the coolant and it is topped up. I am not sure if it is the control unit in the dash because when I push the buttons, the vents that the air is pushed through changes. I also have no air conditioning, does this have anything to do with the heat? Could the heater core need replacing? Could a citric acid flush possibly clean out any contaminants in the heater that are blocking the coolant? I would appreciate any suggestions. I don't really want to go through another winter without heat.

[Benzmac]

How do you know that the valve is open? You should only get cold air out of the center, but I'm sure you know this. I would suspect a vacuum leak that is not allowing the flaps to operate correctly/

Good luck

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Benzmac:
Donnie Drummonds
300E
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 8 YRS
PARTNER IN MERCEDESSHOP.COM
OWNER OF MB AUTOWERKS .COM

I know the valve is open because there is an elbow shaped hinge that is accessible from the outside of the valve that you can feel with your hand. With the car running I reached down and felt the hinge and could feel that it was down, which means the valve is open. If the valve was closed the hinge would be sucked up by the vaccuum.

[stevebfl]

Yes, the 201 chassis has a simple vacuum controlled water valve.

I think the water flow is off with vacuum on the valve. Pull the vacuum line off the valve and see if it moves. If vacuum is needed to close the valve, it will be open with the vacuum line off. Verify the two separate valve positions.

Don't assume just because the external pieces function that the valve actually opens. They are cheap plastic valves and they often fail in this manner.

Yeah but I know for a fact that the valve remains open. Even if the vaccuum isn't working, that would only mean that the valve wouldn't be able to close. With no vaccuum on the valve, the valve is open. Wouldn't this mean I should be constantly getting heat since the valve stays open?