slow heater motor

F

fast fredy

Senior Member
Good morning , have a question regarding my fan blower. I had it apart because it appeared seized . It works but it does'nt seem fast enough. If I connect it directly to the battery it runs faster, more like I think it should. The 2 speed switch works fine and I cant see what the difference should be going through the switch or connected direct . The wires from the switch are original and must be the proper size ... any thoughts? thanks Fred
 
By now thats common. Mainly bronze bushings worn armature excessive end play dirty stuck brushes . Like mine it groans & squeals until it warms up, my cat blows warmer air so I know its time may as well get a new one. Electric motor shops all gone thanks to this throw away society.
 
Direct from the battery is a lot shorter path than through wiring harness and connections at an ignition switch and blower switch. May have worked fine when all was new bright and shiny. Does it speed up when installed with the car running? Someone didn't replace it with a 56 blower did they? I seem to remember seeing blowers with 6V or 12V stamped in the case, but may have been replacements.
 
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I have a similar problem, but i've taken my motor apart and cleaned and lubed it, and the wires to the heater controls and under dash area are in decent/good shape. Everything works, its just not terribly "forceful".

I've just been living with it, but i've never thought to check for a 6V/12V stamp.
 
Could be a number of things as mentioned above. Something you might try.

Check the voltage across the battery, down to a tenth of a volt. Check the voltage at the blower wire, disconnected. Check the voltage on both the blower case (ground side) etc.

Then hook it up and turn it on, and check the voltage again, down to a tenth of a volt.

What you're looking for is either voltage loss thru the switches on the hot side, or poor grounding at the blower motor case. It won't take much loss to slow the motor down. Many times you'll find full voltage with no load, but under load it shows up.

I don't think I've said this as clearly as could be done, but hope it makes sense.
 
check it like a starter, basically a voltage drop test, put a volt meter on it, check for drop of voltage, i would start at the switch, sometimes dirty fuses, not to mention the normal ground losses, those 6 volt ones put out some air with 12 volts on them.
 
delco1946 said:
I have a similar problem, but i've taken my motor apart and cleaned and lubed it, and the wires to the heater controls and under dash area are in decent/good shape. Everything works, its just not terribly "forceful".

I've just been living with it, but i've never thought to check for a 6V/12V stamp.
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Did you have difficulty removing the squirrel cage from the shaft? Mine seems rusted fast. Yes, I did undo the Allen screw!
 
miker98038 said:
Could be a number of things as mentioned above. Something you might try.

...poor grounding at the blower motor case. It won't take much loss to slow the motor down. Many times you'll find full voltage with no load, but under load it shows up.
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the grounding issue can fool you - over time things rust up and do not ground as well. Add to that the times that people have repainted and the ground can be very poor. Test this by installing the blower motor and wiring as it should be but then connect a jumper wire from battery ground to a good ground on the blower motor case/housing and see what you get.
 
Anteek29 said:
Did you have difficulty removing the squirrel cage from the shaft? Mine seems rusted fast. Yes, I did undo the Allen screw!
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Mine wouldn't budge either and believe me, I tried everything! I finally just cut the shaft in half and removed it that way. I'm gonna get a new motor anyway. Not much help, I know.
 
fast fredy said:
The 2 speed switch works fine and I cant see what the difference should be going through the switch or connected direct .
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This person didn't say whether it was six or twelve volt, as far as I could see. I should mention, if replacing the motor is the chosen course of action, I could find no 2 speed replacement motors for my 6 volt system during my complete rewire project a couple of years ago, and I searched far and wide. I ended up using a new single speed motor, though I kept the original two speed switch in place.



Things may have changed in the last couple of years, though. If anyone has a source for a six volt 2 speed heater motor that will fit Fords, let us know...and post a link!
 
I lucked out with mine. I dropped the entire heater box. Pressure tested the heater core which looked brand new since it was inside the box. The blower motor was accessible from under the hood. That was amazingly clean and spun like a new one. Both speeds work and it is as quiet as they were in 1959.

WW Grainger carries 12v blower motors, not sure if they have 6v stock. They have a 12v that I could use if I needed one.
 
fast fredy said:
. . . It works but it does'nt seem fast enough. If I connect it directly to the battery it runs faster, more like I think it should. The 2 speed switch works fine and I cant see what the difference should be going through the switch or connected direct . . .
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Every connection or set of contacts in the wiring has the potential for corrosion or a poor connection. Each one can add a slight amount of resistance that adds in with the others and limits the voltage & current available to run the motor.

Don't forget to check the fan motor Ground wire or its mounting bolts to the body and body / engine connections to the large battery ground cable.
.
 
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