boatdoc

Just going over my somewhat new to me '81 and I see the electric fan switch had no pigtail on it. I found it buried in the starter loom, black taped up. I unwraped the tape and it is pretty melted. I've checked the wires and all seem to be fine and the switch has no continuity at the two posts so I assume it's fine also. Jumping the fan at the pigtail connect, with a battery and a couple of large gauge wires, by the A/C comp the fan works fine.
Could the pigtail at the switch get so hot as to melt some because it's proximity to the two exhaust ports it's in between. I realize this fan hardly ever comes on and I'm sure it won't run much here in the PNW but I would like to give it a chance to work if need be.
Thanks

BTW: Thanks for all the help so far on the other little bugs, she's comming along fine!!!

SIXFOOTER

Yep. likely it got fried by the exhaust manifold. If you connect the 2 wires the Aux fan should run. The temp switch in the head is set to come on at 238*. I would hunt down one that comes on at maybe 210 if you want to keep a stock looking rig.
If your into some mods that make it better, a full on electric cooling system and maybe an aluminum radiator would hook you up.

boatdoc

Danny, I've looked around some for another switch, it seems most of them are of the 1 wire variety. Read one post where they said the supplier of this 1 wire variety one leaves the black wire hanging and unconnected, have you seen or heard of this aproach? I guess the switch opens and closes with itself being the ground not like the OEM haveing two posts. Any thoughts???
Thanks

SIXFOOTER

yes, that switch the contact is between the 2 pins and not to a graound at all. You can use a single pin switch, just connect the blue wire and cut out the black one.

7T1vette

That line has some significant current running through it. If the fan switch or the blower relay had contacts that were badly carboned-up, it would throw more resistance into the line and jack up the current so much that the damaged part and the wiring would get hot. Before you re-connect it, either replace the fan switch and/or the relay...or disassemble them and clean the contacts off and put on some dielectric grease before you reassemble and install them.

boatdoc

Hi Charley, Are we talking about the same switch here? I don't think this switch can be dis-assembled and without going to the book/AIM, it's out in the shop, a relay??? Thanks

7T1vette

If the line carrying high currents (20-30 amps or more) feeds through a mechanical switch and/or relay, burned contacts [from arcing] is always a risk. When that happens, carbon build-up forms, resistance goes up and so does current. The 'excess' current drawn at the burned contacts is immediately converted to heat. Now, if the switch/relay are solid-state devices, that system would not exhibit the same symptoms.

SIXFOOTER

Well, thats close. If the contacts carbon up from arching that does throw in some extra resistance, however, more resistance = less current, but more heat, basic ohms law. Only reason I can think they put in that oddball 2 pin switch is because they didn't have a 1 pin that would carry the current, 20 or 30 is about right.
There are many ways to improve that system, simply replacing the aux fan motor with a new technology unit would be an improvement if you could find one to fit.
My vote would be ****** out all the belt driven fan, shroud, aux fan and all. Replace it with a Dua Spall type setup.

boatdoc

Hi Danny,
I have not had any heating problems at all with the '81 but just wanted to get it back to where it was with these small electrical bugs I inherited. I crawled under the car today and took the melted connector all the way out and got the two spades out of the melted connector. Cleaned them up and stuck them back on without the connector. Kept the wires as far away from any other heat source as I could. I did jump the two before hooking them up and the fan ran fine. I doubt it'll ever come on up here in the PNW but at least now I know all is well as long as the switch is functioning right and I wouldn't know how to test it while it's in the head. I know there's no continuity between the two cold, we'll see when it warms up some with the engine running.
Thanks for all the help, Gary