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Fan motor not running

flamer

Oct 22, 2012
37
Joined
Oct 22, 2012
Messages
37
Hi experts,

So edited my last post as I thought it was a capacitor that had failed and now disproven that, I have a bathroom heat/fan/light all in one unit and the fan has stopped working, what I have done for testing is bypassed all the internal wiring/capacitor and hooked it up directly to a power supply, even then its completely dead. When I cracked the motor open it seems to be in perfect condition, I know this whole unit is only about 5 years old so I am wondering if there is anything else I can check. the wiring to the motor goes through a rubber grommet on the side of the motor so I cant easily test to resistance to check the its all intact but it seems unlikely, the shaft is freely turning, I tried spinning it in both directions while powered applied but its completely dead. no sounds or anything.

The unit is $300 to replace so would love to find something simple to get it working again but I don't have high hopes, both the heat lamps and light work fine.
 

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Last edited:

Minder

Apr 24, 2015
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Apr 24, 2015
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It is a 1ph Induction motor so it relies on the capacitor for the start winding,
The windings look OK, so it may be the cap itself, if you apply power and the same time, give the shaft a spin and if it runs, it is usually an indication of a bad cap, if so you usually can spin the motor and it will run in either direction.
Ensure the rotor spins freely and the windings have continuity.
 

flamer

Oct 22, 2012
37
Joined
Oct 22, 2012
Messages
37
It is a 1ph Induction motor so it relies on the capacitor for the start winding,
The windings look OK, so it may be the cap itself, if you apply power and the same time, give the shaft a spin and if it runs, it is usually an indication of a bad cap, if so you usually can spin the motor and it will run in either direction.
Ensure the rotor spins freely and the windings have continuity.

thanks What I did was apply the power and try spinning it, nothing happened. then bypassed the cap and applied power and spun, still didn't start. there is no buzzing noise or anything. I did also just realise, the motor has 4 wires, one of which is a direct power feed, and the other a power feed via the cap. So I can feel pretty confident now cap is not at fault.

Not sure if there is anything else I could try test?
 

Bluejets

Oct 5, 2014
6,862
Joined
Oct 5, 2014
Messages
6,862
You could do a resistance check.
With the cap run arrangement there would likely be very little difference in the winding resistance from common to each leg.
You may expect to see possibly 20ohms.

It may be that there is a thermal switch in the common leg that has gone open circuit.
If there is and it's buried in the windings then you are out of luck.

Quick easy to follow video here, rather than yack away for hours and get you all confused........
 

flamer

Oct 22, 2012
37
Joined
Oct 22, 2012
Messages
37
You could do a resistance check.
With the cap run arrangement there would likely be very little difference in the winding resistance from common to each leg.
You may expect to see possibly 20ohms.

It may be that there is a thermal switch in the common leg that has gone open circuit.
If there is and it's buried in the windings then you are out of luck.

Quick easy to follow video here, rather than yack away for hours and get you all confused........

that was very helpful indeed I think its proved the fault.

Since I'm a noob I will spell it out incase I have done something wrong as my colours are different to the video, I have -
Yellow - 220v straight
Black - 220v capacitor
Blue - neutral

between blue and black = open loop, between blue and yellow = open loop. between yellow and black= 1k

So you might be right, maybe a thermal cutout is in there, must be tiny and well hidden! i cant get the windings part separated from the motor housing so I might give up and look for a replacement motor. cheers!
 
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