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Discussion Starter #1 (Edited)
I started the car up after the winter after doing a few things to it, brake linings, cleaning carbs, fuel lines, and heater core. I only recall a couple wires coming from the fan motor and one was a ground so I never gave much thought to it and it was running fine in the fall. Anyway, I decided to test the fan and see if I was putting out and heat and when I turned it on the fan came on high as usual, but when I started rotating the switch to slow it down I could hear some arcs jumping and got a little smoke from it. It had a dead spot in the switch and at the low setting I was getting sparks jumping?
So I stick my head under the dash and see a wire loose wire at the heater motor gauge light (missing screw, see other post) and I stick the wire back in the hole with no screw and the light started working. My next question, is do I pull the switch and see what I can find what’s wrong with it? I don’t really see how I could have done anything wrong at the motor, only one way to hook it up, but it’s been a while. The thing that gets me is it was working perfectly last fall! Anyone have any suggestions the path I should take? No, burnt wires under there either.
 

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I started the car up after the winter after doing a few things to it, brake linings, cleaning carbs, fuel lines, and heater core. I only recall a couple wires coming from the fan motor and one was a ground so I never gave much thought to it and it was running fine in the fall. Anyway, I decided to test the fan and see if I was putting out and heat and when I turned it on the fan came on high as usual, but when I started rotating the switch to slow it down I could hear some arcs jumping and got a little smoke from it. It had a dead spot in the switch and at the low setting I was getting sparks jumping?
So I stick my head under the dash and see a wire loose wire at the heater motor gauge light (missing screw, see other post) and I stick the wire back in the hole with no screw and the light started working. My next question, is do I pull the switch and see what I can find what’s wrong with it? I don’t really see how I could have done anything wrong at the motor, only one way to hook it up, but it’s been a while. The thing that gets me is it was working perfectly last fall! Anyone have any suggestions the path I should take? No, burnt wires under there either.
It kind of sounds like the winding in the rheostat switch is frayed or somehow grounding out. I would pull the switch and have a serious look. If you don't see any brakes or mishaps in the switch then I would lubricate the winding with dielectric grease and try it again. You don't want a fire... It doesn't sound like a problem with the fan motor.
 

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Discussion Starter #3
Thanks for the input George, that was the rout I was going to take unless someone suggested something else. Yea, I don't want a fire.... I disconnected the battery, but I usually do that anyway.
 

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Discussion Starter #4
Ok, I pulled it loose from the dash now how does it come apart. What I think I got is like a domestic car master cylinder spring clip but it doesn't have enough slack to pull it over the side. I also tried pulling one end out and I'm afraid of breaking it. I'm also getting allot of porcelain dust out of it? Does anyone repair these if it’s in bad shape?
 

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Ok, I pulled it loose from the dash now how does it come apart. What I think I got is like a domestic car master cylinder spring clip but it doesn't have enough slack to pull it over the side. I also tried pulling one end out and I'm afraid of breaking it. I'm also getting allot of porcelain dust out of it? Does anyone repair these if it’s in bad shape?
It's been awhile but as I recall you need to pry out one end of the wire clip to disassemble the unit. Inside you will find a wire curl in a circle (the rheostat). I (of course being me) clear zinc plated all the bits. I don't think you will brake the clip, but if you do you can always make a new one. Let us know.
 

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My new nephew, dear boy..you have a fire waiting to happen. If the rest of your wiring harness looks like the sample ends you showed us in the photos then you should park the car, remove the battery and rewire it and we all know who makes the best wiring harnesses this side of the Pecos. Really, I am dead serious. My friends Bill Gillham and Carter Hendricks almost lost their lives experiencing car fires in the last few years. This is serious stuff and exactly why I refused to even start my Sprint after a preservation project over 4 years. I wanted every single circuit working down to the dome lights, (which one lens I toasted and smoked) and in order before I lit the ignition. And now that I have figured out the wiper motor connections the car is on the road in shake down mode with a clear confident feeling it isn't going to burn to the ground. If you are getting smoke, fire is right behind.

That said, the switch is NOT grounded. They are getting hard to find so treat it with respect. The wire bale on the back just "worries" off from one end with a small screw driver and the porcelain only goes on one way. Don't fiddle with it if it works even intermittently. Nothing wears out really. Blow it out with some air and snap it together.
The di-electric grease never hurts. The biggest PITA with these switches is the resistance to twist them. There is a seal between the inners and the outers at the shaft and it gives so much friction that the grub screw will tend to wallow out the knob where it goes in. Don't lose the grub screw. It's small compared to the other one you lost and a sleeve in that hole should help save the knob.

The wire connection is 2 yellows side by side- one to the light and one to the motor, the motor is grounded by a second wire-- and the red power goes to the other connection on the switch.......that will be $7.45
 

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Discussion Starter #7
My new nephew, dear boy..you have a fire waiting to happen. If the rest of your wiring harness looks like the sample ends you showed us in the photos then you should park the car, remove the battery and rewire it and we all know who makes the best wiring harnesses this side of the Pecos. Really, I am dead serious. My friends Bill Gillham and Carter Hendricks almost lost their lives experiencing car fires in the last few years. This is serious stuff and exactly why I refused to even start my Sprint after a preservation project over 4 years. I wanted every single circuit working down to the dome lights, (which one lens I toasted and smoked) and in order before I lit the ignition. And now that I have figured out the wiper motor connections the car is on the road in shake down mode with a clear confident feeling it isn't going to burn to the ground. If you are getting smoke, fire is right behind.

That said, the switch is NOT grounded. They are getting hard to find so treat it with respect. The wire bale on the back just "worries" off from one end with a small screw driver and the porcelain only goes on one way. Don't fiddle with it if it works even intermittently. Nothing wears out really. Blow it out with some air and snap it together.
The di-electric grease never hurts. The biggest PITA with these switches is the resistance to twist them. There is a seal between the inners and the outers at the shaft and it gives so much friction that the grub screw will tend to wallow out the knob where it goes in. Don't lose the grub screw. It's small compared to the other one you lost and a sleeve in that hole should help save the knob.

The wire connection is 2 yellows side by side- one to the light and one to the motor, the motor is grounded by a second wire-- and the red power goes to the other connection on the switch.......that will be $7.45
As for the condition of the wires, are you referring to the exposed wires at the terminal or the condition of the wire covering? I’ll have to inspect the harness closer. This car I think will be a lot tougher to wire than the mustang I did. I always thought I would uninstall the old and install the new at the same time verses remove the whole harness and start from scratch with this car.
I’ll pull the switch apart tonight by prying on one side of the retaining clip out. I thought I would ask you guys because the obvious on these cars isn’t always so. I hope I can just blow the switch out and put some grease in it and be done with it. The knob is in good condition and not wallowed out at all. I also didn’t notice and excessive resistance when turning the knob. I’ll trace the wires tonight but I seem to recall the wire for the dash light coming from the other direction for the fan motor? Thanks for the help!
 

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As for the condition of the wires, are you referring to the exposed wires at the terminal or the condition of the wire covering? I’ll have to inspect the harness closer. This car I think will be a lot tougher to wire than the mustang I did. I always thought I would uninstall the old and install the new at the same time verses remove the whole harness and start from scratch with this car.....
p!
If you can change the oil in the car you can start from scratch. It's really not a very daunting project. All the pieces fall into a very clearly logical sequence. It doesn't come out of the box like last years Christmas tree strings from my supplier. Everything is bundled in plastic sheathing with three main courses, one going to the rear; one to the left of the engine bay and one to the right. I see you have Carello connections. You can specify Lucas or Carello bayonets, or spades or loops or whatever you want for any specific connection. There are sub-assemblies for rear lights and Generator, etc. It's all held in place with the metal tabs on the car. The hardest part is loading all the red and white multiples into a fuse end at the box and lying on your back , head under the dash. I converted my 6 fuse system to 8 and basically threw the old away without ever referencing it. It was mostly a Radio Shack special anyway. It does give me a fuzzy secure feeling I'll never have to track grounds and shorts again. It's also a good time to re-establish grounds in the car, clean all the sockets and change out bulbs.. After you do it, you will thank me for doing it.
 

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Discussion Starter #10 (Edited)
If you notice the wire clip that holds this together there is a little piece of wire welded on it and it won't come off the case on one end.
 

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It's been you and I till now, so I'll pass to the group the baton. It can be fixed with a hardware store spring, Dremel, and some careful reassembly. You are lucky the car didn't catch fire because the welding action was centered around 12 volt battery and was caused by a short
 

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Greg,
First of all I want to say thar our "Uncle" knows of which he speaks. Personally I think his suggestion to replace the coiled wire with a hardware spring shows great ingenuity and resourcefulness. Having said that I would suggest you carefully disasemble the remainder of the switch(taking pics as you go along) and clean up all the individual pieces. I used a Dremel tool with a polishing wheel to remove the corrosion on the center contact ring and the contact arm. The pic of the bale is a little dark to see exactly what the problem is but I think that will work As for the wire bale, I think judicius use of Dremel with a cut-off wheel will allow you to remove the wire bale.What ever you do,do it with caution.

Good Luck,

John Viereg
 

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Discussion Starter #14
Can I replace the coiled wire with a spring? The thought the coiled wire was made of a type of metal that created more resistance the farther up the spring the contact point was rotated slowing the fan motor down? If I just replace that with a spring it won't be a variable resistor any more right?
 

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Greg
You have your electrical theory correct - the original coiled wire is resistance wire - NOT piano wire that a coiled spring is made from. Good luck in finding that.
It is possible that someone may chime in here with a source ... otherwise, you may have more luck in substituting the wire from a lesser brand of automobile.

Regarding that "little piece of wire welded onto one end of the clip ..." - there lies your smoking gun. That clip came into contact with the resistance wire... causing a short ... which caused a puff of smoke ... as the remains of the wire welded itself to the bail or clip.
 

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It's been you and I till now, so I'll pass to the group the baton. It can be fixed with a hardware store spring, Dremel, and some careful reassembly. You are lucky the car didn't catch fire because the welding action was centered around 12 volt battery and was caused by a short
There I go adding to the "misinformation"! Thanks, George. Lucas did offer a push pull switch that was an on/off, no variable speed switch which is probably the safe bet.
 

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Discussion Starter #17
I'll have to look at it closer after work tonight but I think I can just leave the resistance wire out. I think the switch makes direct contact when first turned one then when you turn it, it comes in contact with the resistance wire.
 

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Discussion Starter #18
Does anyone know the fuse size for the fan motor? They are hidding it pretty good in the manual.
 

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All the fuses are originally 8 amps ... but since #3 carries so many different circuits ... it generally works better if you use a 12 amp for that one.
 

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Discussion Starter #20
All the fuses are originally 8 amps ... but since #3 carries so many different circuits ... it generally works better if you use a 12 amp for that one.
I was going to try and find some coiled Nichrome wire to replace the one that was in my switch and I assume I will need to know what kind of amps the fan motors pulls at start up. Thanks! I already know more about this switch than I wanted to.
 
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