Air conditioner fan not blowing

[Paul's brother]

I have a 1977 with factory under dash AC and the fan doesn't blow. The compressor activates and makes cold. The under dash unit has 12 volts going in. The fan wheels spin freely by hand but won't energize. I assume either the fan motor or the switch is faulty. Before I consider further disassembly, I'll take advice on servicing the under dash unit. Are the motor and switch even available? All I see are entire replacement units.

 

[Slowleak]

The motor and switch’s are serviceable. The problem is that you have to disconnect the hoses and pull the whole unit to even get to the switch. You need to anyway as your evaporator is likely clogged with gunk and needs cleaning.
I have a ‘77 as well and went thru the entire system a few years ago. New switches, hoses, expansion valve, bigger condenser and a Sanden compressor. It will cool a lot better if you go thru it and do it right. The switches are easy to find. The motor is probably ok unless it was making noise. It can be rebuilt or replaced as well…
The evaporator has flare connections on it but you can still find fittings that work on your new hoses, and you will want new hoses….

 

[Broncobowsher]

FYI, there are NO factory installed A/C systems. They are all aftermarket. Maybe dealer installed before it was sold new, but never factory installed.

Being such, there are/were several brands of A/C systems. So advise for one version may not apply to another.

With that out of the way, these are very simple systems. Even if the exact part isn't available, there are generic parts that will work. I just got a brand new A/C evaporator that is 99% identical to the old under dash units that I am working on putting in the back of a cargo van. It has all new controls. Electronic fan speed control instead of a rheostat. And the parts are cheap. The only possible issue is the motor, you may need a size or shaft that isn't common. But the rest of the electrical system is simple.

 

[Dne007]

I'm totally unfamiliar with these units, but my common sense wonders if a test light can make it to the blower motor and see if DC is making to the blower? or a little tappy on the motor to see if will break free? When did it last work?

 

[Slowleak]

I am assuming this is a Ford dealer installed ARA kit like most were? If it is, and the issue is the switch or motor, as it appears to be, it will still have to come out and be disassembled to get to the switch or wiring.
Those old switches normally lose speeds before they totally give out. Mine was down to low speed only before I bit the bullet….

Sent from my iPad using Tapatalk

 

[Slowleak]

Something I just thought of is that the motor has an external ground wire. You might check to be sure it is still functioning. Mine is on the passenger side, if you look behind the motor you might get lucky and be able to find it. Without that ground, it will behave just like yours…clutch works but the blower doesn’t. Provided that yours is like mine.

 

[904Bronco]

Something I just thought of is that the motor has an external ground wire. You might check to be sure it is still functioning. Mine is on the passenger side, if you look behind the motor you might get lucky and be able to find it. Without that ground, it will behave just like yours…clutch works but the blower doesn’t. Provided that yours is like mine.

I had the same thought... check the ground.