need location of auxiliary fan relay switch 1984 300SD

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rickw - 07 Sep 2006 18:01 GMT

Aux fan stopped working. Will run with temperature switch disconnected
from drier and terminals jumped. Tried disconecting temp sensor on
thermostat housing (with engine running) and grounding lead to engine
but fan will not operate with this test. Fuse is okay, checked with
voltmeter and getting ~10v on both sides of fuse terminal. Sounds like
a faulty relay, but I don't know location of aux fan relay. Any help or
other suggestions?

Thanks

Rick

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Karl - 08 Sep 2006 02:27 GMT

Your aux fan only runs on A/C high side temp. It is NOT controlled by engine temp.

The temp sensor on the thermostat housing is the cold blower lockout.
It keeps the blower fan from turning on when the engine is cold. As the water warms up, then the
blower comes on. This feature is overrode when defrost button is pushed.

There are no water temp sensors on a 617 engine for the aux fan.

> Aux fan stopped working. Will run with temperature switch disconnected
> from drier and terminals jumped. Tried disconecting temp sensor on
[quoted text clipped - 7 lines]
>
> Rick

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