1973 AC / heater fan

[moveoverGM]

Hi guys and a very Merry Christmas to all of you!! Just wanted to say thank you all for the abundance of and valuable information that you have shared over the past year with this newbie F100 owner.
When I bought the truck I was not prepared for amount of interest it would generate. It is a true classic!!
On cold mornings like we have been having the fan works great for a little while then just quits. I turn it off for a few minutes and it works again for a while. Is this a symptom of a failing motor or perhaps the dash switch going bad? Just thought I would ask on the chance there might be someone out there that has experienced this with their ride. Thanks for any suggestions.

Donald.

 

[Fellro]

Is the fan rattly or noisy at all? If so then the bushings are out. I would certainly start with the fan as they definitely can behave that way.

 

[moveoverGM]

Actually, the fan makes almost no noise at all even at full blast. Just the sound of the air moving.

 

[TheBandit]

From the sounds of it you have the classic signs of a motor gong bad. I'm not positive but it sounds like the motor is getting to hot and shutting down on the thermal overload protection built inside of it. (if it has it).
As stated before changing that motor would be a great place to start.

 

[Ozzie]

Check to see if the fan motor turns easily. If the bushings are dry sometime it will increase drag on the armature causing the thermal switch to "shut it down". If so, a drop of non-detergent oil on each bushing will work wonders.

 

[dustybumpers]

Sounds like the fan resistor is going bad
That's the little box in the duct work held in with 2 screws where all the wires connect

Eventually only fan speed that will work is high speed

 

[moveoverGM]

Wonderful suggestions guys!!! I will take a look at that. It makes perfect sense to start with the fan motor first. I doubt that the fan motor has had any service since it was new. If all else fails I can order a new one and change it out.
Thanks again, Donald

 

[BKW]

Sounds like the fan resistor is going bad
That's the little box in the duct work held in with 2 screws where all the wires connect

Eventually only fan speed that will work is high speed

D3TZ-19706-A .. Blower Motor Resistor-Use with factory installed integral A/C or Hi/Lo Comfort Vent System / Obsolete

1973/79 F100/350 & 1978/69 Bronco.

GREEN SALES CO. in Cincinnati OH has 1 = 800-543-4959.

NOS PARTS LTD in Waxahachie TX has 4 = 972-937-2201.

 

[moveoverGM]

Thank you Bill!