need location of auxiliary fan relay switch 1984 300SD

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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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.

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