wierd electrical problem

[uiuc240]

Someone has to have some thoughts on this...

I've got dual 12" FAL fans in my car. I've had them for three years with the same thermoswitch setup. In the last two months, however, I've melted TWO fuse holders...WTF?

It's wired from the battery, through the 30 amp fuse, to the fans. The ground side has the thermoswitch on it, which acts like a relay by completing the ground circuit and turning on the fans.

This setup has worked fine for a long time, but for some reason, now the fuse holder is melting. The fuse isn't blowing...the holder is actually melting and causing the circuit to break. I thought the first time it happened it was just an anomaly, so I replaced the holder. Now it happened again and I'm confused.

Is something wired improperly? What would cause a fuse holder to melt instead of the fuse simply blowing? I'm confused an frustrated. Any ideas are welcome...

If no one has a good solution, I'm just going to rewire everything through a relay and a switch. Blah.

Thanks!

Eric

[Ritz S14]

Have you done anything to your car prior to the fuse holder melting?

Hooking up a relay on the ground(thermoswitch) side to provide 12v to the fans sounds like a pretty good idea. Sometimes the a 30amp fuse can be too big for the fans, so it just melts instead of popping. Pics sometimes may help.

[uiuc240]

Well, the thermoswitch *is* a relay, so I'm not going to do that. Right now the 12v goes directly from the battery, through the fuse, and to the fans. The *ground* goes from the chassis, to the thermoswitch, and then to the fans.

And what do you mean by the fuse being too big for the fans? Why would that cause the FUSE to melt? If the fuse is too big and there's a malfunction in the fan, the *fan* should simply fry. But if the fuse is properly sized (30 amp is what it needs) and the wiring is properly sized (which it is - 10 gauge) and the fan has a problem, the fuse should blow. But it's not. What's happening???

Someone?

I can't take a pic. I'm at work. Car's at home. Thanks again!

Eric

[uiuc240]

A friend of mine proposed "HEAT" as the cause.

Hmmm...

I *did* recently rewire the whole system to make the wires shorter. The holder is now by the battery...before it was by the driver's headlight. Maybe there is just too much heat there and it's not playing nice with the plastic. Perhaps I should just wire it so the holder is in a cooler location. Who'da thunk it?

Eric

[idlafie]

Someone has to have some thoughts on this...

I've got dual 12" FAL fans in my car. I've had them for three years with the same thermoswitch setup. In the last two months, however, I've melted TWO fuse holders...WTF?

It's wired from the battery, through the 30 amp fuse, to the fans. The ground side has the thermoswitch on it, which acts like a relay by completing the ground circuit and turning on the fans.

This setup has worked fine for a long time, but for some reason, now the fuse holder is melting. The fuse isn't blowing...the holder is actually melting and causing the circuit to break. I thought the first time it happened it was just an anomaly, so I replaced the holder. Now it happened again and I'm confused.

Is something wired improperly? What would cause a fuse holder to melt instead of the fuse simply blowing? I'm confused an frustrated. Any ideas are welcome...

If no one has a good solution, I'm just going to rewire everything through a relay and a switch. Blah.

Thanks!

Eric

What you are experiencing is probably not a short but your fans are drawing too much current thru your wires and causing the wiring to be severely stressed. That's why the fuse doesn't 'blow' but your fuse holder melts. 30 Amps is WAYY too high of a fuse rating for your dual fans. What gauge wiring are your running it on?....12? 14? 16?...Try going down to a lower rated fuse...like maybe 15 or 20 amps. If it blows then you most likely have a bad wire or a poor ground. RE-CHECK ALL your wires coming from the battery & to the fan along with the thermoswitch & relays. Sounds like something's going bad on either the switch, relays or wires. When you check your wires, make sure to feel them between your thumb & forefingers as you trace the line. Melted wires sometimes aren't usually seen but can be felt when pinched between the thumb & forefinger as you trace them. If you do run new wires, run a 10 or 12 gauge wire and make sure it's wrapped with a plastic heat shield type tubing wrapped, (I forget what it's called), in black electrical tape used for automotive applications
Anyhow hope this helps.
ID
'95 SE

[uiuc240]

Well, the fans are shipped with a 30 amp fuse (the fans draw 19.5 amps). And I was using 10 gauge wire. I'll recheck everything, but I'm pretty sure the wiring is fine. And I'm pretty sure the fans are fine.

Everything worked fine for 3+ years. Then I moved the fuse to a location closer to the battery (and closer to hot things) and it's been having issues. I'm going to try moving the fuse location first, and then troubleshoot other things.

Thanks,
Eric

[matic 240sx]

where is the holder exactly? ive never had them melt.. maybe you should run it in the fender