Box fan motor is frozen during a repair


  #1  
Old 07-30-21, 05:30 PM
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Box fan motor is frozen during a repair

One of my box fans started to screech where I couldn't use it. I followed a how to disassemble
the unit to see if it could be salvaged. I got as far with that as I thought prudent.

The shaft turned very slowly under power. Previously the fan had tipped on it's face running
and I was not there right away to pick it up.

Once inside I saw this old fan had a lot of dirt in it. You can laugh at the next part:

After blowing out with air I used some brake cleaner in those works. Appying power at the switch
I can hear a hum like it wants to run but the shaft assembly does not turn.

I bought some of the right kind of 3 in 1 lubricant-- (blue 3oz label) but have not applied any
in the bearing area.

Is this appliance salvagable?


 

Last edited by lon in appleton; 07-30-21 at 05:32 PM. Reason: typos
  #2  
Old 07-30-21, 05:47 PM
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If you got brake cleaner into the fan bearings then you need to get oil in them now.
Brake cleaners remove all oil.
 
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Old 07-30-21, 06:46 PM
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Ok thanks for the prompt reply.. I'll go on to the next step.
 
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Old 07-31-21, 04:11 AM
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Be careful with the oil. Your motor may have an internal switch whose contacts could cause electrical problems if covered in oil. With power applied to motor, try spinning the shaft in the running rotation. If it continues to rotate at reasonable speed, either the motor is defective or a start capacitor is defective. If the shaft does not continue to spin, the motor is defective.
 
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Old 07-31-21, 04:16 AM
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I put a few drops of 3 in 1 oil on the bearings/bushings while it is lying flat so gravity helps pull the oil into the bearing. Spin the fan blades by hand while there is a small puddle of oil on the bearing to help work the oil in. Just keep turning you should feel it start to loosen. Then repeat with the bearing on the other side. When done don't forget to wipe off an excess oil.
 
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Old 07-31-21, 11:15 AM
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Just to follow up for anyone else with problem like this:

I'm pretty sure what was said about the motor being shot is the right answer and I bought
a replacement fan. The one that went bad I had for years and did the usual dust cleaning without
any opening of the unit. I did note that there appeares to be metal filings in shaft housing,
the circular ring that hold it in placw where I put the drops of oil. I had used compressed air
but I could see that the metal was still in there.

After adding a bit of the Blue label 3 in 1to the round bearing cavity below the flywheel-- still nothing.
With no power the flywheel turns free and you can do a temp reassemble for the shaft and spin it.
But applying the power from the switch grabs the flywheel magnet and freezes everything.

It's applying the power that stops the shaft from turning, not lack of free play.

Anyway thanks for the responses. I now have a 3 oz dropper bottle of 3 in 1 blue can that cost
$5.00 and tax. Why so high for it? The sales staff just put it in my hand. I didn't do any
careful shopping on it. :-/
 
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Old 07-31-21, 11:29 AM
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It's applying the power that stops the shaft from turning, not lack of free play.
That is an indicator of worn bearings. The shaft can spin freely but when powered the armature is drawn in to the windings, hits and freezes the shaft.
 
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Old 07-31-21, 12:48 PM
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That could have been caused by the metal filings. As they used to say on Star Trek-- "It's dead Jim." ;-)

But I have an additional question.

The broke fan is an Aerotron like the other three I have. I spent the time trying to fix it because apparently
it put out more air _and_ made less secondary noise-- that hum you hear in the backghround when
these box fans run. The new one which is a Lakso makes the noise as well.

My question is on fan physics. ;-)

If I slowed down the blade on a sample older fan by putting tiny round magnets for example on the tips of the blades, would that make the unit better for night use when the secondary hum is really noticeable?

My idea was that the dust accumulating on the blades might have changed the speed to kill the noise.
 
 

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