Motor whistling...

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Rock Crusher

Member
Location
Ne. USA
What would make a motor whistle? or is it possibly the equipment it is hooked up to run?
It's a single phase motor, 120v, 3/4 hp, 1400 rpm. The diagram was followed as to how to connect it. It is for a commercial range hood exhaust and was installed yesterday. Friend of mine wanted me to look at it, but since I don't know a whole lot about motors, all I did was verify the connections.
Thank you
 
T

T.M.Haja Sahib

Guest
My guess is the whistling comes from the exhaust hood.......
 
R

Rock Crusher

Member
Location
Ne. USA
That was my thought, but since I'm an electrician, not a hood guy, I thought I'd post it to you guys.

And just to clarify the wiring diagram.
L1 Hot - one wire only attached per the diagram
L2 Neutral - two wires per the diagram
All others tied together - showed all others tied together.
 
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growler

growler

Senior Member
Location
Atlanta,GA
Rock Crusher said:
What would make a motor whistle? or is it possibly the equipment it is hooked up to run? It is for a commercial range hood exhaust and was installed yesterday.
Click to expand...

A high pitched noise can be caused by friction. A bad bearing or to much tension on a drive belt.

You have to see what the noise is and then see what could cause it. It normally would have nothing to do with the electrical hook up but things like belt tension would cause a problem.

Some electricians that I know burned up some window exhaust fans by really tightening the drive belts.
 
S

Strife

Senior Member
Agree.
Belt too tight, or bad bearing/s.
That's if it whistle all the times.
If it whistle at start up only, it could be the speed of the motor can't match the force against the belt right away.
I've had an AC that would whistle at start up. The problem was the motor was strong enough to go full speed on, so the belt skipped a few turns before it engaged the fan at full speed.

growler said:
A high pitched noise can be caused by friction. A bad bearing or to much tension on a drive belt.

You have to see what the noise is and then see what could cause it. It normally would have nothing to do with the electrical hook up but things like belt tension would cause a problem.

Some electricians that I know burned up some window exhaust fans by really tightening the drive belts.
Click to expand...
 
ritelec

ritelec

Senior Member
Location
Jersey
Fulthrotl said:
when motors don't know the words, they don't whistle,
they hum.... are you new?
Click to expand...

No, No No ......if I where..........I'd off the profession ....

templdl said:
That's strange as they usually num.
Click to expand...

OK OK :D hum........doesn't know the words. I figured whistling wasn't lyrical either so I threw it in there.

talk to your self ...............money in the bank?

What's whistle???

Buy the way.........to the OP. Yes, could be mechanical.


Closest I could get to a whistle is :eek:hmy: although it more looks oral......but this :eek:hmy: and this....:lol:.................
 
PetrosA

PetrosA

Senior Member
Location
Lancaster, Pennsylvania
I've had a similar situation once, but it was an old hood with a new motor (Dayton OEM parts). What happened that time was that the original motor was run on a variable speed control and the new motor made an awful whistling kind of noise when it was hooked up through the original switch. Called Grainger tech support and they explained that because of the new laws regarding energy efficiency, all their new motors were cap run and would not work with a variable speed control. Replaced the switch with an off-on and all was fine.
 
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hurk27

Senior Member
Location
Portage, Indiana NEC: 2008
Fulthrotl said:
when motors don't know the words, they don't whistle,
they hum.... are you new?
Click to expand...

Naw you got to get in order, they only hum when they don't know how to whistle because they don't know the words:p


Ok back to the OP.

This can be anything, from bad duct work design, to air flow obstruction, such as a damper not opening, to a simple hole left open causing a flute effect like the rungs of my ladders on the roof of my truck when I'm going down the road, I doubt it is the motor but who knows it could be?
 
H

hurk27

Senior Member
Location
Portage, Indiana NEC: 2008
Rock Crusher said:
View attachment 6525
It's connected 120v.
L1 hot (black)
L2 neutral (white)
All others from motor wire nut together.
Click to expand...

if the rotation is wrong the blower will run faster as the load will be less,

if the blades are flat then it doesnt matter in most 360? housings, if the blades are cupped like a C then the open side of the C is the direction it should be going in:

>>>>>C>>>>>> Like this

was rotation checked?
 
ritelec

ritelec

Senior Member
Location
Jersey
??? remove the belt or blades or whatever to confirm it is or isn't "the motor"..............

whistle to me would would be air flow................

opening in duct work ............???

It is only happening when the motor is "working". Maybe it has something to do with Disney's Snow White and the Seven Dwarfs "whistle while you work"...............


OK OK through me a bone.
 
R

Rock Crusher

Member
Location
Ne. USA
It isn't the motor. Took the belt off the pulley to confirm that. We put the filters in above the grill and the whistling stopped. We must have squished one of the dwarves:jawdrop:
We're guessing the airflow restriction caused the motor or pulley to slow down enough to stop it. Either way, it has stopped and he is happy.
 
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