I'm new to this site today so any pointers on how it works or something I need to do please let me know.
I have a 1990 300TE with 135k miles.
I just started having heater problems. It works fine as long as I'm moving above 10 MPH. When I stop the heater blows cold air. As soon as I speed up it starts working again. It seems like a vacuum leak? Is there a servo that controls the heater? Any help would be greatly appreciated.

It sounds like your auxiliary water pump is not working. Use the home page to do a search using the google search feature. Here is a thread about it.

http://www.peachparts.com/shopforum/showthread.php?t=76367

Chris

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1987 300TD 309, xxx 2.8.2014 10,000 mile OCI


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Thanks for the information, I'll check it out.