How to check a GE fan motor with a multimeter ?? Any electrical guru’s out there?

[John Landstrom]

I have a 1930 GE fan motor and don’t know how to test it to see if it reads correctly to run.  
I Really don’t want to have to assemble the whole thing just to see if it should run.  Is there anyway I can use my Klein multimeter to test the continuity by attaching it to the two head wires?  If so, what do I turn the dial to and what should it read?   
The front motor cover is off and the two head wires are sticking out about 1.5”.   Just a note, the rotor for it is trashed so actually trying to run it with power would be difficult at best.   
 

Pictured below is the multimeter I have.  If you could tell me which setting it should be on and what it should read I’d really appreciate the help.  
 

 

[Louis Luu]

3 minutes ago, John Landstrom said:

I have a 1930 GE fan motor and don’t know how to test it to see if it reads correctly to run.  
I Really don’t want to have to assemble the whole thing just to see if it should run.  Is there anyway I can use my Klein multimeter to test the continuity by attaching it to the two head wires?  If so, what do I turn the dial to and what should it read?   
The front motor cover is off and the two head wires are sticking out about 1.5”.   Just a note, the rotor for it is trashed so actually trying to run it with power would be difficult at best.   
 

Pictured below is the multimeter I have.  If you could tell me which setting it should be on and what it should read I’d really appreciate the help.  
 

 

Same here...I would like to learn how to use this contraption.

[Steve Cunningham]

unplug the fan.

Set the meter for continuity. Touch one side of the plug. Then touch the other to the fan body. If it beeps, you have a short in the stator. 
 

Touch both leads to the plug prongs, and set the meter for resistance. At off, you get total resistance. As you move through the speeds, at each speed you should get different resistance.

[Mark Olson]

Since the two wires are sticking out of the stator, set the meter for Ω and test the two wires. You should get some reading above zero. As Mr. Cunningham stated, any reading from a stator wire to the frame will indicate a short.  The meter is probably capable of reading MegΩ, so make sure you are not touching any conductors or frame when taking the measurements, else you may get a "false positive" from your body resistance. With two wires protruding from the stator, you may very well have a shaded pole motor, which is by far, the easiest type to repair. Post pictures, please.

[John Landstrom]

Steve….no plug. Stater wires cut short due to old broken insulation.   It already had a new power cord wired to the stubs, since removed.  Now the motor sits with front motor cover off.   
 

Mark….I’ll take a couple of pics.  The motor is from the same model/vintage fan as the one I just finished refurbishing. (AK1 / AOU 75425).  

Edited November 2, 2022 by John Landstrom

[John Landstrom]

Pics of the motor.  
 

once I hook it up to the multimeter I need to know the reading(s) I’m looking for.  
 

[Mark Olson]

That is a shaded pole motor, and the coils look okay visually, or don't look burnt.

As far as an exact ohm reading, I do not know and it is actually not very important. The number of turns per coil is the important part.

The coils should not read open, or infinity, when tested across the lead wires and they should read open, or infinity when tested to the stator frame.

Edited November 2, 2022 by Mark Olson

[John Landstrom]

3 hours ago, Mark Olson said:

That is a shaded pole motor, and the coils look okay visually, or don't look burnt.

As far as an exact ohm reading, I do not know and it is actually not very important. The number of turns per coil is the important part.

The coils should not read open, or infinity, when tested across the lead wires and they should read open, or infinity when tested to the stator frame.

Above my old and tired brain.   Could you walk me through setting up the multimeter (where do I turn the dial), then what to look for on the readout.  Then what do you mean by stator frame?  What does an “open” reading look like?  Can I just attach to the two wires and get a reading?  And YES, you’re dealing with a total novice.  I use the tool for home electrical work…..simple stuff. 

Edited November 2, 2022 by John Landstrom

[Mark Olson]

Set the meter to Ω. Ohms. The Greek letter omega, the upside down horse shoe.

Touch your test leads to each other. You should get close to zero.

Touch your test leads to the wires sticking out of the stator. You should get some non-zero number, maybe 75 Ω (who knows?) If you get no reading, OL, or whatever your meter reads when the leads are not touching each other, the stator is open.

To test for short to ground, touch one lead to a stator wire and the other lead to the bare steel motor. If you get any reading other than OL, or whatever your meter reads when the leads are not touching, you may have a shorted stator.

That meter is probably capable of reading many meg ohms, so be aware of touching the wires or motor with your hands, it will skew the results. Any reading with high megohms may be okay, any reading of k ohms or less is bad.

[John Landstrom]

I’ll give it a try in the morning and let you know what I got.  Thanks.  

[John Landstrom]

Mark,

Here are the numbers and info related to what I’ve done so far.  
First off understand that I only have the small pencil type probes that make it hard to get a good connection without using your fingers to pinch the wire to the probe.  
 

1.  Touching probes together = 0.0.  2.6

2.  Touching probes to the two head wires - readout bounces around a lot from about 2.2 to 580, sometimes OL.   Hear to just touch the probes to the loose wires.  If I pinch the wires to the probes with my fingers it settles down a bit but still jumps from a small number (say 1.5 or 2 to 10-15.

3.  Touching one wire (pinching it) and touching the other probe to the motor casing or interior metal returns OL.  
 

Wired up a pigtail to the leads and plugged it in.  Motor buzzed loudly.  Noticed that the rotor was trying to turn once I spun it with my fingers.  Immediately stopped.  Seemed like it might be hanging up on something.  Removed and checked both front and rear bearings and regreased and loosened them.  I remembered that I hadn’t sprayed the inside if the stater nor the rotor with insulating varnish so I did that to the stater and rotor. (as I did to the fan I just refurbished)

I also noticed that the shaft seemed to be binding a bit when spun slowly but hand. Appeared to only be on the rear bearing.  So I filed and sanded the broken end a bit.  I did chuck the rotor in my drill motor and don’t notice any wobble.

** Note Forgot to mention that this motor was from a donor fan and the “screw end” of the rotor shaft that engages the gears in the gearbox was sheared off.  (See pic). Also no base plate or speed control came with it, so I’m attaching the power wires directly to the head wires. 
 

Haven’t tried it again yet this morning.  Just finishing my coffee and listening to th pouring rain outside.  (Pacific Northwest)
 

[Mark Olson]

Okay, I am not trusting those numbers. Since you have a pigtail wired up, use your meter on the plug end and make sure you are getting good contact (lay the plug on the bench and press the probes down on the prongs).

You didn't trip a circuit breaker, that is good. The rotor needs to be centered in the stator radially and axially. The rotor must not drag on the stator and the bearings must not be loose. Usually, the end bells need to be bumped around a bit while tightening the screws, progressively, to get everything to line up properly.

Edited November 4, 2022 by Mark Olson

[Mark Olson]

Also, use your amp clamp to get a current reading when you plug the motor in.

[Mark Olson]

Here is the manual for that meter. Use the range button to select low ohms.cl800_manual.pdf

[John Landstrom]

I’ll check out the end balls/bearings again.  When I fiddle with them and tighten too much they don’t move at all.  Getting them aligned perfectly that way isn’t easy.  Oh, by “loose” I mean they’re just tight enough to rotate a bit to allow for easier assembly.  They’re not moving much.  
As for the “end bells” I’m assuming you mean the motor end caps that house the brass rotor bearings and gearbox.  If so the screw holes for each are lined up exactly with the stater screw holes.  It has to be for the 4 screws to thread in properly.  There’s not a lot, if any, “bumping” the end cap.  Besides, only the front one comes off.  I’ve never figured out how to remove the rear cover that the gearbox attaches to.  
 

I’ll check the readings on the pigtail plug and check out the manual (which I have) to see how to do what you’re referring to.  I take it I’ll be putting it around the pigtail wire.  
 

oh, and I’m assuming it’s okay to try to run the motor without the speed control….?

Edited November 4, 2022 by John Landstrom

[Mark Olson]

The shaded pole motor will be fine without a speed control. If it gets too hot to touch, turn it off. They need the air from the blade to help cool them.

[John Landstrom]

Okay, here”s try #2….

Turned the dial to the omega sign.

1.  “Touching leads together”.  Putting the multimeter leads together = 0.0

2.  Touching the leads to each of the plug posts (+/-) = 8.9

3.  Touching one of the plug terminals and the other to the motor housing or the inside of the stater = OL

Turned the dial to the A setting (with the two symbols ~ and …) and putting the plug wire inside the orange loop I get the following:

            ~ reading is 0.0.  Hit the SEL button and

           … reading is 2.72

If I select the V setting I get

           ~ reading is .090

           … reading is 0.0

[Mark Olson]

When you check amps only one wire should go through the loop. When both wires go through the loop they cancel each other out, hence the 0.0 reading. If your Amp reading is good, that is high. Is that with the motor assembled?

The volts reading will be useless without touching the probes to a device under test with power.

The  8.9 Ω seems low, but that may be okay.

[John Landstrom]

I’ll have to change the wiring setup to different wire so I can separate them to check the amps.  Tomorrow.  
at this time the motor has the front off and the rotor out.  That’s the extent of the disassembly.   Can’t get the stater out of the pressed steel case.  They’re notoriously difficult and there’s a risk of damaging the stator trying to remove it.  (I’ve tried the “pipe” method on another one, but that really only works on the older cast iron motors.  
 

I’ll send more tomorrow.   

[Lane Shirey]

Buy a $20 kill a watt meter on Amazon. Then you don’t need to use the current clamp on your meter.  Much easier. 

[John Landstrom]

Second try replying with this info this morning.  “Livin’ in the woods” satellite internet sucks.  
 

Lane:  I’ll. Heck it out if necessary.   Don’t want to spend any money on it if possible.

Mark:  switched to separate wires to allow each to be tested individually for the amps and volts.  Calling them wire #1 and #2.  Did readings with the motor “I did readings with the motor “unassembled” (rotor and front cover removed) and assembled.  All readings done with power to the wires.
Below are the readings I got this morning.  

AMP READINGS
Motor Disassembled 

Wire #1   ~ = 2.99   … = 2.86

Wire #2   ~ = 2.97   … = 2.86

VOLT READINGS 

Wire #1   ~ = 1.55-1.73   … = 0.0

Wire #2   ~ = .085-.097   … = 0.0

 

 

[Mark Olson]

Okay.  That is reasonable for a motor not assembled. The whole motor running should  be name tag amps or so

[John Landstrom]

Mark, 

When disassembled the motor got pretty warm to the touch when power was on.

Forgot to put down the assembled, power on, readings when assembled. 
 

Assembled and plugged in.  Also got warm.  Just buzzed louder and rotor never turned.

AMPS

Wire #1   ~ = .167  … = 2.61

Wire #2  ~ = .165   … = 2.59

VOLTS

Wire #1  ~ = .239  … = 0.0

Wire #2  ~ = .054  … = 0.0

Edited November 5, 2022 by John Landstrom

[Mark Olson]

I am sorry to hear that your fan motor project is not going well. Send me the motor and I will fix it up for you.

Do not worry about removing the stator, it does not need to come out.

[Anthony Lindsey]

John,

Be sure that the motor case is COMPLETELY closed all the way around.   It is very common with the stamped steel GE motors that when you put the front cover on that it isn't completely all the way in.   Look very closely and there is a good chance you will see it isn't mated all the way in all the way around.   The results of this is a buzzing sound and the rotor not turning.   I used a plastic hammer to pop the case in on these.   It is very common on these models.

If possible send a picture from the side.