The Stovebolt Site Forums The Shop Area The Electrical Bay Heater Switch

Working on the wiring harness. Have heard that even on new harnesses, the wires can be labeled incorrectly. But removed all the individual bundles to re-directed to the AD locations and checked continuity of all switches. Have a replacement ignition switch coming to replace the defective new one that tested on when the tumbler was out. Then would go open with the key in and on. ugh.
So I checked the heater switch. Are these suppose to be wired to the ground leg of the blower? In the off position, I have direct zero ohm continuity from the terminal in the 7 o'clock position to the dash clamp always. None to the 3 o'clock terminal. In 1st on position, .4 ohm between 3 o'clock and 7 o'clock, and 5.2 ohms from 3 and clamp. Next is 2 ohms between 3 and 7, and 6.7 ohms from 3 to clamp. Finally from 3 to 7 is 3.5 ohms, and 3 to clamp is 8.6 ohms. It's a good thing I'm checking all this stuff.
I cannot find the box or instructions, and can't find anything in the inter web either, being this wasn't factory. I've found pages with the layout of the firewall and fan and switch locations, but no wiring diagrams or references to ground connections.

Normally, a rheostat switch could be connected either on the hot side or ground side of the motor, but the fact that you found the terminal connected to the ground clamp is concerning. I would contact the supplier for a wiring diagram. I'm assuming it's a new switch. Maybe someone here has more info for you.

I can find it on a few sellers sites, but I guess I'd have to contact them to ask for manufacturer info. Most stuff nowadays is made in Asia, and I don't speak Mandarin... very well.
It is porcelain, so can dissipate the heat created.
I'm wondering if it is a ground side rheostat, with the 7 o'clock terminal as a ground connection to make sure it has a good ground source instead of biting thru dash paint from the clamp.

Well, just discovered something new about this switch finding info on Jim carters site. Didn't find it anywhere else though.
It is backlit. Behind the knob is a bulb, which means it will have continuity thru the incandescents, and a ground source is required.
More testing after I remove the bulb. Duh.

That switch is made by Standard. You can find the specs on their website.

I also used a rheostat switch, also from Standard. Mine is 6v and I'm pretty sure it's connected with one wire to the motor.

Search for Blower Motor Switch

Standard Part # HS-98

Maybe archive this.
The bulb gets its V+ from 3 o'clock connector when switched on. Ground side from mount clamp. Output to fan is 7 o'clock. Easy-peasy.
This entire time it was the bulb throwing me off.

So the light is always on when the ignition is in ON position? You'd think that there would be 3 terminals. Voltage in for light, voltage in for fan (from ignition ON), and output for fan.

The light on mine only comes on when the switch is turned on. It glows brighter at high speed and diminishes in brightness as you turn the knob toward slower speed.

My switch looks similar. The light stays on whenever the ignition switch is on. I like it that way. Puts out light down low where it doesn't bother my night vision and also reminds me that my switch is on if left on. Might be the way it was wired by my mechanic.

Yep. The light comes on when in on any of the 3 speeds. Off when off.
On a side note. The new ignition came in. It functions exactly the same way as the other new one. Key off and out and all contacts connect. Put key in and on, and posts go open. Fudge.
So I opened it up. The brass triangle is stamped 180 out.
Tomorrow I'll fire up the drill press and make new spring pockets in the black plastic.
Made in China.

So when it's dark, you have to fumble around in the dark to find the heater switch?

Check your PM's

That was the tail end of a generation that had to set timing, throttle and steer from that wheel thingy in front of them...all in the dark.