During the summer the h-vac blower was very inconsistent. At times it would
choose not to work. Now that it's cold out, it chooses not to work at all.

 

Inconsistancy is not a symptom of a fuse, it is a problem with the blower

 

And the blower is well hidden. The R-34a must be drained NUTS!

 

I replaced my H/AC blower motor from the engine bay. No draining of refrigerant or removal of heater core or ac equipment. I can’t find my information, but roughly it goes like this:
1. Disconnect battery ground
2. Remove the round cover
3. Unscrew barrel fan from shaft
4. Cut bracket of fan motor
5. Cut wires, leave excess
6. Unbolt rest of bracket
7. Cut last of bracket in two places
7b. Remove pieces of bracket out of hole
8. screw barrel fan to new motor shaft correctly
9. solder new motor wires to old wires
10. bolt new motor bracket in place on the engine bay side
11. install round cover
12. connect battery ground

 

I found this: https://www.ford-trucks.com/forums/9...ngine-bay.html
hope this helps.

 

I'm assuming since you were using it in the summer, your truck has A/C. Is that correct?

 

A.C. ? I refer to HVAC and 134a freon. The Ford folks state that the freon
must be drained and hoses disconnected to reach the blower motor. You
fine folks have shown me a better way to get the job done......in spring time.
I will try to up load the newest pictures of our Stella with her new fresh
paint. She was a Viking Edition from a Minneapolis Ford dealer in a
beautiful...non stock deep purple. With the XLT Ranger trim...WOW!!!
What a looker! with those white stripe tires and wheel covers.

 

I'd 1st ck that power is constantly getting where it is suppose to go (blower motor) and any switches involved are working properly.

Blower motor is deep inside the big evap box, and behind the evaporator and heater core.

 

May I assume the red & white wires are the blower motor and can be
reached under the dash behind the glove box...I hope?..next spring.
It was 15 out this morning. Stella gets stored for her long winter's
nap real soon.

 

I seem to remember that yes you can get to the blower 2 wire elec connector. It is slightly under and just behind the dash

 

OP mentioned freon, so it has to have A/C .. No freon = no A/C

But, there were THREE DIFFERENT types of A/C for 1973/79 F100/350's.

Only factory installed integral A/C has the HUGE evaporator housing in the engine compartment and with integral A/C, the A/C controls are in the same panel as the heater controls.

 

I hunch that with the pictures provided, there's enough tech. support
to get the blower running or replaced next spring. I appreciate everyones
input.

 

I snooped under the dash behind the glove box looking for a pair of red/white
wires and a connector. NO GOT. When I have more time....in Spring,
I'll check out what's there with a circuit tester...ice-pick with a bulb inside and
a ground wire.