Strange electrial issue, need expert help
04-29-2002, 09:57 AM
#1
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Strange electrial issue, need expert help
Well I finally got around to rewiring my cooling fans. The PO must have invested in the company that makes black electrical tape. My fans have been a little strange ever since I owned the car but now that summers getting here it was important to get it all worked out. I found 7 splices from factory harness to one fan and 3 in the other. So I just started from scratch at the harness and ran all new wire. Here’s the problem following the wiring diagram and matching the color codes on the AC fan there should be a Green/Yellow wire that is hot with the AC switch and a Brown ground. Simple huh... sure... Ok with a meter I get 12v to the Gr/Y with the switch on. I've got good ground. Attach the fan, nothing. I've tried 3 fans 1 brand new and the 2 that are in the car. All of them work fine when attached hot, and ground. So in my troubleshooting I put the meter on the Gr/Y with the fan connected and I'm not getting 12v as soon as I disconnect the fan then my 12v returns. I'm not sure where to look for this issue. I thought it might be a relay but never heard of one cut out under load most either work or don't. I've checked to make sure Gr/Y is not grounding out anywhere and its not. Short of starting at the fuse panel and running a new Gr/Y not sure what to-do. Any ideas?
Thanks
Chris
Thanks
Chris
04-29-2002, 12:51 PM
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Burning Brakes
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When you connect the fans the 12v drops to 0v? Or does it go low. If it's going low then you've got a 12v signal thats meant for a relay. I'll look at my wiring later on and see if I can help you out.
04-30-2002, 10:33 AM
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Thought about that too. When the harness is connected and checked at the plug I still have 12v but when the plug is plugged into the fan I loose it. I really would think it was a fan issue if the fans didn't work correctly on any other wire. I just can't figure a relay, but I guess I'll have to break-down and buy one just to test it.
04-30-2002, 05:24 PM
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Measure the resistance across the fan. Then measure the resistance across the harness with the a/c on and off. Do that and we'll talk about the results. Also measure the resistance from the hot wire on the fan to chassis.
Also, edit the subject to ask for someone with the factory manuals so you can see a good diagram of the wiring. Sorry I don't have one.
Also, edit the subject to ask for someone with the factory manuals so you can see a good diagram of the wiring. Sorry I don't have one.
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04-30-2002, 05:32 PM
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Chris, what year is your car ? The earlier 944's are different that the later ('85 1/2 and on). For instance, the early models have a 2 pin thermoswitch, while the later models have a 3 pin thermoswitch (2 switches/ 2 temps).
-Bob P.
-Bob P.