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Discussion Starter · #1 ·
Help!
I replaced the blower motor in my '71 about two years ago. Worked fine for awhile, then I got a burning smell inside the car, and found the wiring connectors on the relay melted. John sent me a copy of a wiring diagram, and that has helped me some, but I'm still confused...
1) I cut back to a non-melted portion of the orange wire; put a new connector on, and reattached it to the relay. Got nothing.
2) The 25A heater circuit fuse in the fusebox was blown. Replaced it. Do have 12V on both sides of the fuse. Still nothing.
3) The blower speed switch was replaced by the Previous Owner with a three position switch under the dash. The "on" positions feed either the yellow or light blue wires, which looks right (they go to a resistor, to determine blower speed?)
4) The switch is fed from a Tan (Brown?) wire, with Zero Volts.

I have voltage at the fuse, but nothing at the switch. Where could I be losing my voltage? The wiring diagram shows the brown wire going to two mysterious circles, with Light Green and Tan wires hooked to them; before feeding the stock speed switch. What are these?

Can I just run a new wire from the fuse box to the three position switch, eliminate the relay and burnt connectors, and be done? It looks like that would let me feed the yellow and light blue wires leading to the resistor, and send juice to the motor. Dark blue out of the resistor, to the purple wire that feeds the blower, and voila.

What color wire is what blower speed? What speeds are fed from the fusebox; and which speeds are fed from the relay (10Ga black wire to positive battery terminal, inline fuse holder, 12Ga orange wire.)

Am I making any sense?
Many thanks,
mark.
'71 Fodor
383
No Heat.
 

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No schematic on me at the moment. I think the mysterious circle things you are talking about are the lever controls. If you pull the dash look down on the assembly, you will see them and the connections. Brown wire should head there.

The orange wire you worked on. Was that the orange wire to the heater relay under the hood?

Somebody sure has had their fingers in there. Is there a reason that you can't replace the switch with a factory style switch? They are about $12.00 new. Part of the reason is that the factory switch has 4 positions to it. Your set-up sounds like it doesn't have the dark blue wire. This lead makes the fan run on high speed (if I remember right).

The relay under the dash is either the blocking or anti-dieseling relay. It is not the heater relay. That's under the hood by the fan. I'm not 100 % sure and hope someone corrects me if I am wrong. I don't think you need either the blocking or anti-dieseling relay to make heater circuit work. I think I would just unplug them until the cold weather passes. Just guessing but I don't think you're A/C is working.
 

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Discussion Starter · #3 ·
John,
You are right about my A/C not working. (I should have mentioned, the compressor is on a shelf in my garage.) As it's November, I'm anxious to get the heat working again!

The relay I'm referring to is under the hood, near the firewall, next to the blower box. The orange wire that was toasted is the small one (18Ga?).

Where do I get a new factory style switch, and how hard is it to get to the back of the dash plate to put it in? That sounds like the best way to go. What color wire feeds this switch? If it's the tan (brown?) one, that still leaves me stuck as to why I don't have voltage.

The diagram is a little hard to follow; I'm not sure which way the electrons go. Does the heavy lead (with the inline fuse holder) feed the whole kit 'n kaboodle? Or is that just to supply the fan on high speed, to keep too much current from going through the wiring under the dash?

Not to be obtuse, but what do you mean by "lever controls"? I haven't pulled the dash to see them, and that sounds like a big job. Is it?

Thanks for all your help. I appreciate it very much.

mark.
'71 Fodor
383
 

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I usually don't like to go for work-arounds but since you are cold, this should help. It's 80 degrees here.

"The relay I'm referring to is under the hood, near the firewall, next to the blower box. The orange wire that was toasted is the small one (18Ga?)."

The two relays I mentioned earlier.(under the dash) are part of your problem. The small orange wire runs down there. They are located under the glove box area. You should see the other end of the small orange. Unplug the connectors. This will stop the small orange from burning.

"Where do I get a new factory style switch, and how hard is it to get to the back of the dash plate to put it in? That sounds like the best way to go. What color wire feeds this switch? If it's the tan (brown?) one, that still leaves me stuck as to why I don't have voltage."

One source for the switch is in the attached link. Check around including the site sponsor Ground Up. You might be able to beat the total price.

The diagram is a little hard to follow; I'm not sure which way the electrons go. Does the heavy lead (with the inline fuse holder) feed the whole kit 'n kaboodle? Or is that just to supply the fan on high speed, to keep too much current from going through the wiring under the dash?

The brown lead runs all fan speeds except for high. As you might have figured out all the low speeds are run through the resistors. The relay under the hood is not actuated except in high speed. In high speed the fan gets power from the separate fused line under the hood through the relay. In high speed, 12 volts is applied to the dark blue wire. Dark blue is the relay coil. Dark blue gets 12 volts through the switch. Its power source is the brown wire just like the other speeds.

"Not to be obtuse, but what do you mean by "lever controls"? I haven't pulled the dash to see them, and that sounds like a big job. Is it?"

The level controls are the levers next to the switch you slide side-to-side. There's a couple more switches that open and close as you move the levers. That's how brown gets connected to tan. Sounds like a problem with one that keeps popping the fuse. Do a search on the name CECIL in this section. Think he had a problem with the same switch on his 71.

As a temporary idea only:
If it was my car and since you have a extra switch installed.
1, Unplug those relays under the dash.
2, Apply 12 volts to the dark blue wire on the fan relay under the hood. Fan run?
3, If so, find the dark blue wire under the dash on the fan speed switch. Run that to your extra switch.
4, Run a wire from the IGN terminal on the fuseblock to your extra switch. These should be the only two wires on the switch.
This should safely run the fan on high only until you get parts and straighten things out.
http://www.true-connections.com/cat/page47.htm
 

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Discussion Starter · #5 ·
Update: The inline fuse supplying the "high speed" line was also blown, so I disconnected the orange lead to the under dash relays.

After fiddling with the dash levers, I now have 12Volts at the brown wire. So, with my three position switch, I can energize the yellow or light blue wires, and run the blower on "medium low" or "medium high". That'll work for now. I also put a 20Amp Self-Resetting Circuit Breaker in line before this switch; so hopefully that will trip (if needed) before I blow the 25Amp glass heater fuse at the fuse block.

This will get me through the winter. Thanks for the link to the levers and switches -- I'll definitely be looking to go back to "factory style" when I redo my interior. As soon as I get some time, and some money...

Thanks again for all your help,
mark.
'71 Fodor
383
 

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I would stick to an in-line fuse holder with a fuse instead of the circuit breaker. You still probably have a problem somewhere in the brown or tan wires. The fuse should go faster if it acts up again.
 

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<BLOCKQUOTE>quote:</font><HR>Originally posted by John_Muha:
I would stick to an in-line fuse holder with a fuse instead of the circuit breaker. You still probably have a problem somewhere in the brown or tan wires. The fuse should go faster if it acts up again. <HR></BLOCKQUOTE> - I concur, it is better to blow an in-line fuse then to burn a wiring harness. Please check for burnt / fraied wiring that can com in contact with the body(This means track and examin that wiring



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Steven K.
 
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