Hi All,
Yesterday my 1983 Mercedes 300D started running hot. Today I noticed the auxilary fan was not working. I checked the fuse and it has juice going through. I even noticed the fuse was hot with a cold engine and key off... Is that normal?

Before I get one on EBAY (Does anyone have one on the list?) can I run wires directly into the fan plug to test it? Will that cause any harm? Anything else I should check?

Suggestions are greatly appreciated!

Bobby Koziak
1983 300D 112K

 

Hi Bobby, I have a used and working fan from an '82 300TD...but I'd rather get yours working.

It's very likely the problem is the aux fan relay. It'll be hidden in the engine compartment under that little (4" x 5") black box probably on the inner fender...with lots of electrical wires running into the box. If the aux fan relay isn't clearly marked you'll have to trace some wires back and forth to figure out which relay is which. In the meantime, take two wires and connect them to the battery and without touching them together go to the two wires running to the fan motor. One will be brown and it's the ground. The other will be 12v+. Strip the wires or find a way to energize the fan directly from the battery. Checking it for a split second (that's all you'll need) won't harm a thing.

There's a way to check the relay...but let's hold off till you take these steps. Good luck. Dave