Fan speed (Air) knob fidgety

[73WaggyCustom]

New to me 1973 Wagoneer Custom. It has factory AC, the under-dash Clardy manufactured unit with two knobs, AIR and TEMP. The AIR (fan speed) knob is a little fidgety, in that it doesn't always seem to turn the compressor on (air does not get cold) although it does control the volume of air blowing out of the vents just fine. If I turn the knob slightly in either direction the compressor will kick on and the air blows ice cold. Sometimes I have to "hunt" with the knob until I hear the compressor click on. Does anyone know if I can take the knobs and faceplate cover off of the unit and do any "servicing" that might remedy this situation? I am very inexperienced with this and don't want to make it worse or break something...

Thanks for any suggestions!

[sonoraed]

Pull the switch out and see which style it is

The switch with 5 prongs is the most common , most parts guys can handle it, the switch with coils is really old style but available


Sent from my iPhone using Tapatalk

[73WaggyCustom]

Thank you so much, Ed! I went to the UAC web site but couldn't find it?? What do they call those parts?

[73WaggyCustom]

Never mind... I found them! Thanks again!

[sonoraed]

No problem glad you got fixed


Sent from my iPad using Tapatalk

[73WaggyCustom]

Due to circumstances I won't actually be able to work on this until later in the summer, or maybe fall. I am just trying to figure out how to approach it. Once I get to actually open it up and take a look I'll probably be back with more questions... Thank you so much for your willingness to help. That is what is so great about folks involved in this community!

[73WaggyCustom]

Here’s the fan switch. Doesn’t look like either of the other ones. It has three wires attached. Any idea where to source one?


Sent from my iPad using Tapatalk

[Stuka]

The physical shape should not matter much so long as its functionally the same. The 3 prong one linked above will likely work, but I don't know that it will for sure work.

[73WaggyCustom]

I installed the three prong switch linked above. It is a 3-speed switch. The good news is that the ac comes on with the first click and blows cold. The bad news is that the fan only blows one speed, which seems it must be high speed, no matter which position the switch is in. Anyone have any ideas? Is there a resistor somewhere else in the system that may need to be replaced? Appreciate any help as this is my first attempt at ac electrical repair.

[JWestfall]

My 71 has the same switch as your stock one. I was able to clean up the contacts with electrical cleaner and a strip of fine sandpaper. (The brass part that moves as you spin the nob and contact the coiled up wire). It works fine for me now. Good luck

[Srdayflyer]

there generally a resistor associated with the blower motor on tate model fsj's i believe is located on the heater core housing in the engine bay, if the fan is working the default speed would be running on high the resistor steps the voltage down so the blower motor spins slower.

[73WaggyCustom]

Thanks for your responses. I’ll try cleaning up the stock switch and reinstalling it.


Sent from my iPad using Tapatalk

[sonoraed]

I think you will find that your evaporator has no external resistor it is built into the switch you have, the first picture with 3 prongs should interchange with your original switch,I have ac installation instructions that go way back at my old shop will take look and post if I find them.

[73WaggyCustom]

Thanks Ed! Appreciate it. When I attached the 3 wires to the new switch I just guessed which went where. That could be the issue…

[sonoraed]

I’m thinking three wires will be, ign switched,blower motor, to thermostat


Sent from my iPad using Tapatalk

[73WaggyCustom]

Sorry for the much delayed response. I cleaned up my old switch as JWestfall suggested and it works fine now! Thanks also to sonoraed, I connected the wires correctly this time...