1980 300d heating issue
 

The climate control will not heat. I have the dial turned to highest heat, press one of the button, ie auto hi, and it will not heat. If I press the off button, the system continues to blow air. Sometimes it will stop on its own after 5 or more minutes, other times if I turn off the car, it resets. I assume the lack of vacuum is what stops the blowing air.

Heat did work, but car started to over heat. I found that the cooling system was low on coolant. I had to fill up the radiator and over flow tank. Heat cycle the engine a few times to get all the air. Took three times of heating the engine, letting it cool so it would pull in coolant from the over flow.

The temperature gauge would go from 80 up to 120. It would 'bounce' up and drop back down. I believe pockets of steam hitting the sending unit was the cause.

After refilling the system, heat worked. However the engine seems to be 'consuming' coolant. I have to keep filling the over flow container. I see some evidence of fluid loss by what I assume to be a heater control valve on the passenger side of the engine bay. But not enough to require the amount of fluid loss from the over flow tank.

I would guess I have a broken head gasket.

So, two issues: 1. Heater doesn't work. 2. Engine is using cooling fluid.

Ideas? Suggestions?

First, there is no overflow tank on your car from the factory. There is just the cap on the radiator and an overpressure vent tube to the ground.
http://www.flickr.com/photos/durinsday/8194263790/
http://www.flickr.com/photos/durinsday/8194263790/ This looks and acts like an over flow tank. I filled it with water, warmed the engine, let the engine cool and water was missing from this tank.

Second, if your climate control servo is leaking its cracked and needs replaced. Very $$$$. That is also the reason you have no heat.
This is a much cheaper and far more reliable replacement: UnwiredTools, LLC.

IMG_8081 | Flickr - Photo Sharing! http://www.flickr.com/photos/durinsday/8194263618/ I assume this is the climate control servo?

If its burning coolant you will see white smoke in the exhaust. If its draining into the engine/transmission you will have milky oil or ATF.
Remove the exhaust manifold, if the engine is consuming coolant you will have a wet exhaust port.[/QUOTE]