I'm not getting much hot air blowing anymore from my 1985 300d turbo deisel... 80% of the time it just blows cold air. This is a big problem, especially here up north where it gets very cold.

Any suggestions for fixing the heater? Thanks.

Also, whats the best online source to download a PDF of a repair manual for this car?

 

Thanks ForcedInduction. Much appreciated.

I'll have a look for this monovalve by the battery this weekend. Just one question: what does it look like? I don't want to unplug the wrong thing.

As for the manual, I contact mercedes and they sell the one I need for $195. Here's the link: http://shop.mercedes-benz.ca/index.c...&CategoryID=28

There must be a cheaper option?

Thanks.

 

I have an 85 300 TD Coupe with the same problem. Blower works fine, but no herat. I tried removing the monovalve core om case it was jammed- no warm air, double checked the circulating pump - it is working, Other good ideas?

MJR

 

You can remove the monovalve and block off the top of it so it flows freely (or simply bypass it with an open junction). If you then still don't have heat you know it's a physical obstruction in the system. If you then get heat, you know the problem is the valve: it's either not working or it's not being told to work by the climate control computer. If it's the computer your options are to test the temperature selection wheel for proper operation, the temperature sensor in the dash, or the computer itself.

 

I must have a physical obstruction in the cooling system. Is there an "approved" way to try to blast it clean?

MJR

 

Flush and refill. There could be a cruddy buildup or there could be air. Even if your pumps have failed the hot water should still circulate slowly on its own. If you don't feel like flushing the system you can always try to massage the hoses to see if they have an obstruction you can clear without getting into it too far.

 

many thanks

will try as you suggest and if no fire or explosion follows, I will be pleased...it needs flushing anyway...