michaelathome

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Randy V

So what's dr. bob - chopped liver?

MainePorsche

dr bob was referring to battery voltage at each side of the fuses.
OP was doing the diagnostics in the WSM which involve measuring testing at the fan controller of signal control from amplifier and test function signal - 7v at controller with ignition ON/engine OFF/AC switch ON.

CT Rob

Thanks to Dr. Bob and you as well!

-Robert

CT Rob

Replacement fan installed, but it isn't getting enough voltage/current to spin it.

I have a spare of the module that goes by the passenger seat, but my mechanic believes it is the one under the hood that is hard to find.

Thoughts?

Thanks!

-Robert

Alan

The inside controller is easy to swap - just try it. Just unplug the old one and try the new one loosely plugged in. I believe ROG100 can sell you a refurbished (by Greg Brown) fan final stage.

Alan

CT Rob

Will do -- I left a note for Roger, knowing that he likely won't see it until he gets back from Canada.

Thanks!

-Robert

fraggle

Standard checks, first check fuses, then swap leads and verify it isn't the fan itself, then test the final stage test by swapping with another car. If it doesn't work, then try swapping the controller next to the passenger seat.

Captain_Slow

+1 The above is exactly what I did and in the end it was the controller by the passenger seat. If fans still don't work right after swapping final stage and controller box with known good ones... then it gets ugly, looking for bad solder joints at connections or broken wires (not nearly as common as either of the controllers dying).

Fraggle - we missed you today...great turn out at Chris's up on the mountain.

CT Rob

Tried an extra controller I had picked up...no difference, so I ordered a used output final stage. Now it's the wait for it to come in.

-Robert

CT Rob

Final stage fan controller picked up used, installed, and it's back in business.

-Robert

Bilal928S4

Rob,
Great to hear you got it working.

TheoJ

hi,
good to hear that the problem is solved. Yes, the fan power stage does this. Typical effect is that one fan runs full speed while the other is silent. The fan controller box at the seat cycles through a test cycle which you can hear in the fluctuating RPM. Every 30 secs or so the controller tries to find out if the other fan runs or not. If it doesn't the running fan goes to full power again. Normally they both run about half power.
For the record: sometimes it is the controller box itself that causes the problem but mostly the powerstage is at fault.
regards
Theo Jenniskens
1992 928GTS
The Netherlands