84 300 D Turbo

Does anyone know if there is a troubleshooting guide to discover why your auxiliary fan doesn't work? Can someone provide steps to discover the cause of this unfortunate circumstance please?

Also, if I am unable to troubleshoot it do to specialized tools I would like to put a manual control in, a switch in the cabin. Is there a way to do the modification that makes the switch and wiring look very natural and built in/original?

I pay attention to my gauges while driving, and I am planning boost & pyro gauges so barring supernaturally oblivious behavior I think I could manage a switch.

Thank you for your time!

-Chris

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1984 300D Turbo.