Need a pic (info) on the defrost switch

[Katfish]

I was hoping to add (repurpose) a light switch to the defrost spot for an OD control signal for my 518.
It looks like the defrost switch is different?
Why in the world would they create a whole different part for such a simple function.
Am I missing something here?

My pic shows the light switch in upper right, and defrost location in lower left.

[dodj]

I might have a switch panel with a defrost switch still installed...I will look...24-48 hours please... with wind chill -32 outside...don't wanna go out to the garage today.

[Katfish]

No hurry, appreciate the help.
A little searching showed it is actually a different part.
UUUUUUgh.......that blows up my plan.
There's one on eBay for $120!
No way in h*ll am I going down that path.

I guess the next step is to see if I can mod the light switch to fit, before abandoning the project.

[Indiana Challenger Guy]

I'm currently installing a new dash harness and bench testing my dash on my 70 Challenger. It has a rear window defroster. Will this picture help?

Let me know if you need further.

Brent

[Katfish]

Thx, that confirms it.

[dodj]

I'm currently installing a new dash harness and bench testing my dash on my 70 Challenger. It has a rear window defroster. Will this picture help?

Let me know if you need further.

Brent

your switch appears upside down.....

[Katfish]

How can you tell?

[Indiana Challenger Guy]

Wow dodg, that's a great catch. I had no idea. I went back and found a picture when I disassembled the dash. You're 100% correct. I will need to correct that now. It's always easier now with it on the bench..

Katfish, I've attached a picture I took during disassembly, I apologize for the confusion. Kudos to dodg for seeing that.

Thanks again,
Brent

[Lunchbox]

How can you tell?

Just noticed it has TOP on it, I will have to take note when I start putting the dash back together.

[Katfish]

I'm back with another question, so the defroster switch has 2 setting?
I'm guessing it's a high and low speed?
Does the switch have an internal resistor to drop the voltage to the fan?

In essence, how would you test the switch?
Check continuity between the 3 terminals?

[SRT392]

Rod  i believe so as there is one wire back to the fan.  i have that option so the test was when i plugged it in and did a smoke test..  mine works but that moto is loud compared to todays motors..  if you need a switch let me know as i have several inst pnls i salvaged out

[dodj]

I found a switch as well. Although, maybe it's because I'm holding in my hand while operating it, it doesn't seem to switch smoothly. It kind of snaps to different positions sharply. Tested it electrically and the two switched spades are independent of each other and have continuity to the common terminal.
As to shipping it to you, I think getting it from SRT392 is likely more economical than from me in Canada. I'm willing to check if you like but cross border rates are usually a bit on the stupid side. And...I also recently heard Mr T has applied 100% tariffs on anything from Canada so that might play a part..I don't know. Rules change every few hours it seems.

[Katfish]

Unfortunately 392 didn't have 1 in his stash.
I'll send you a PM.

After some research I found (as you did) the 2 output pins are independently connected to the input.
The high/low speed is achieved (for 70 only) by a special harness between the switch and motor.
It's 2 parallel wires, 1 is 20g and the other 18g, so there's more voltage drop on the 20g path for low speed.
On later years they put a resistor on the motor.