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97 TA cooling fan issues

1390 Views 2 Replies 2 Participants Last post by  95pontiacff6sp
Just bought a 97 TA 6 speed after a couple weeks starting to have a few electrical issues, car sat for a couple of years, highly modified. 383 forged bottom end supercharged alot of chassis work done rear end beefed up, willwood big brake kit all 4 corners, frigging thing is a beast to drive!!! Any how fighting the Vats system but just about got that figured out, while trying to start car one of the fusible links burns out, now cooling fans inop which are direct wired with single on off switches for each one. Installed new fusible link and fans both turn on then link burns up, Fans inop again,not an electrician but with some guidance can figure this out. Basic troubleshooting but need to get this back on the road. Thanks for all the info on this forum. Steve
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It would seem your problem is that both fans draw too much power for the fusable link.

I imagine the fans are wired with power going through the fan switch then onward to the fan motor itself.

DC electrical has a fatal flaw in that it doesn't travel well. Power loss is big, especially if too small of wire, or corrosion sets into wire or connector pins.

There is a solution, however. It will involve separate fusable links for each fan. Then instead of wiring power through the fan switch, you will use a relay for each fan.

This is how a relay functions. The standard relay has 4 terminals marked 30, 87, 85, & 86. Terminal 30 gets wire from fusable link. Terminal 87 gets power wire that goes to fan. Terminal 85 will get another power wire, but since it's power for the relay coil, it can be like 18 gauge wire. Terminal 86 goes to one side of fan switch. Other side of fan switch goes to a good ground. Finally fan motor ground wire gets run to a good ground.

Here's how it works. When you flip fan switch on, the relay coil gets it's ground through the switch. The power to the relay coil causes a magnetic field which closes the points of the relay and power flows from terminal 30 to terminal 87 and on to the fan. Fan runs.

The beauty of using a relay is the wire from fusable link to fan is now very short with minimal power loss. The wire from fusable link to fan should be 10 gauge wire or bigger.

The system will use 2 fusable links, 2 relays and either 2 fan switches, or if your good with wiring a single fan switch that has separate circuits designed in for hooking up both fans to 1 switch.

But since your a beginner, 2 fan switches might be easier for you.
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Thanks Coco for the quick response, found where the wires passed through the firewall shorted out, repaired wire and put grommet to keep it from happening again!
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