Okay, I have tested both the fan and the aux. water pump. When i apply power to them, they both work; no strange noises, seem fine.

Does this leave the ACC unit itself as the likely problem? Again, when i check the wiring harness, several leads coming in have voltage (at various levels).

Also, people have recommended fusing the line to the aux water pump. How are folks doing this? In line fuse spliced into the power line? What size amp fuse?

Also, do folks recommend used (from junkyards) ACC's or is it best to bite the bullet on this one?

And, Mobetta suggested checking the temp air tube. What and where and how do I check it?

Thanks, folks, Happy New Year!! and happy motoring.

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1983 300 D