Question re Heater controls

[Tony.dreamer]

hello Folks
I am in process of dismantelling the heater control box with the sliding knobs !
I wonder what does this piece marked in the photo do?

 

[m_thompson]

Variable resistor for fan speed control.

 

[Tony.dreamer]

Variable resistor for fan speed control.

Thanks. This is from my 71 4speed with AC .I carefully pulled the whole thing apart and this piece was intact but very dirty. I wasted it with earring soapy water and fine brass brush . Hope it will work.
On my 73CSA which runs great and everything is working , I don’t notice any change in fan speed when I slide the knob that rides over this resistor? Would you elaborate how it works ?

Thank you
Tony P.

 

[HB Chris]

It controls speed of the fan, less resistance higher speed.

 

[teahead]

Soapy water? I would have washed it w/electrical cleaner.

 

[Tony.dreamer]

I have used soapy water for years for electrical
Components distilled water rinse . Let it dry I never had an issue.

 

[Tony.dreamer]

It controls speed of the fan, less resistance higher speed.

But I thought the speed is controlled by the knob and not the slid MG lever !!!

 

[sfdon]

Two fans Tony...
Slider is blower fan.
Knob is AC fan.

 

[Tony.dreamer]

Thanks Don!
I feel like dumbo! It has some corrosion on it . If it’s to contact the copper piece for changing resistance I have to remove some of that corrosion!

 

[Belgiumbarry]

you have to take it of the box and will clearly see the sliding contact point on the wires....

mine was broken ( a few years ago )

 

[Tony.dreamer]

Thank you!
I will check for that when reassemble the unit! It’s completely Dismanteled now and the rusty main plate is being Zinc di-chromate plated . And the Cooper sliding piece that slides against this piece is being copper plated, as it’s actually made of brass but Cooper is a better conductor so it had a layer of copper on at one time tat is now completely corroded.

 

[Tony.dreamer]