6v blower motor will only run on 12v

[Fleetwood Meadow]

In my ‘52 Cadillac it has 4 6-volt blower motors, 1 on the firewall, 1 under the front seat and 2 under the rear seat. When you turn on the heater 3 of them turn on, the firewall, front underseat, and 1 rear underseat. The rear underseat heater that doesn’t run is the last one on the circuit. They hadn’t been used in about 50 years so they all took a little work to get spinning. This one has a lot of friction in it when you try to spin it. I cleaned it as best as I could then hooked it momentarily to a 12v battery and it spun very fast. So I put it back in the car and turned it on. At first it ran, slowly, but consistently. I had the car running to keep the battery charged. So while it was running I started getting the other rear heater to run. When I got that one running the other one stopped. Now I can’t get it to work at all. It stated smoking so I disconnected it. Obviously there must be something internal that is acting up but everything looked fine when I took it apart. Any ideas?

[Ben Bruce aka First Born]

Any ideas?  You already KNOW the answer. Too much resistance! Either mechanical or electrical.   If it runs as it should on the bench, look at the mounting. In a bind? Grounded well?

 

  Ben

[Joseph P. Indusi]

I believe this is a 6 volt car and 4 blower motors is a large drain on the battery when idling at night with the headlights on.   The smaller Buicks (Specials) had one blower on the firewall and one under the front seat.   I believe the larger Buicks had one extra one under the front seat for a total of 3 and I think some Cadillacs also had 3.   If it were my car I would move one of the rear seat ones under the front seat and leave under the back seat with none.  Once these engines heat up you get enough heat with 2 or 3 blowers.

Good luck and Happy Holidays.

Joe

[Fleetwood Meadow]

It doesn’t run on the bench though. It only runs with a 12 volt battery attached to it. How do I correct the resistance? 

[Frank DuVal]

You say this one has a lot of friction. You mean the shaft is hard to turn? If so, the bushings need to be cleaned and lubricated, and even then I have had some bushings not recover. Typically they will sort of spin when cold, and then heat up as they run and then seize. This causes the excess current to flow, burning the commutator, armature or field. 

 

It it is tricky to take apart a typical heater blower motor, as the brushes are about impossible to reinstall!😁

[Fleetwood Meadow]

I can spin it by hand easy enough but if I try to flick it to get it to spin a couple times without me pushing it the shaft immediately stops. I wanted to take the shaft out and clean everything but how do you get the blower shaft to come loose from the propeller fan blades? 

[MCHinson]

You can probably buy a replacement motor cheaper than you can fix that one. There are usually some on ebay. Other than that, take it to a local electric motor shop and they will know what to do with it.  

[Larry Schramm]

A friend just had the same type of problem with an electric motor on his vehicle, except his kept blowing the fuse for the motor.  He took it apart, cleaned everything and lubed up the bearings/bushings, reassembled it and it works fine now.    This is where I suspect you are.  Old grease and dirt putting a large drag on the operation of the motor.  If you can take one apart, clean, lube, reassemble it.  If you are unable to do that, then Matt Hinson has the best idea.

[Fleetwood Meadow]

How do I get the fan blades to separate from the shaft? Obviously it’s pressed on so I can’t just pull it off. 

Edited December 26, 2018 by Meadowfleet (see edit history)

[MCHinson]

Typically there is a small collar with a setscrew that holds fan blade assembly onto the shaft of a blower motor. You should be able to loosen the setscrew that secures the fan assembly to the motor and then slide the fan blade assembly off of the motor shaft.