Extractor Fan start capacitor

[tona955]

Hi All,

My small extractor fan motor is running slow and need a replacement capacitor. the existing capacitor was painted over so I cannot see its markings or value. I have tried a 25microF cap and it is still running slow.
Is there any way to work out what cap size I need for this motor? I have attached a pic of the label on the motor, all I can see on the existing cap is HALE45 but this was a cap I took from my old faulty compressor and the extractor ran fine with it for over 4 years.

Thanks in advance chaps

 

[carbon]

Not very clear on my phone but from the motor data plate looks like it should be a 25uf capacitor. If it’s still slow with a replacement possibly time for a replacement motor

 

[WorkshopChris]

Does the motor spin freely when rotated by hand, not a bearing getting tight.

 

[tona955]

Sorry, I meant to say i have already tried a new 25micro farid cap and it is still slow.

The motor turns free when powered off, its not belt driven.
Should I try a 45microF cap?

 

[Hog-Rider]

I'm probably wrong on this reply lol,I did not think that the Capacitor had thing to do with the speed of the motor ? I thought that the Capacitor was for the start up I.e. Taking the initial pressure off the Motor on start up.. Just a Thought.

 

[tona955]

Well yes, I can understand your thinking but this slow speed running happened before and changing the capacitor brought the fan up to normal speed, so i suppose it does effect speed.

 

[BarrieJ]

Well yes, I can understand your thinking but this slow speed running happened before and changing the capacitor brought the fan up to normal speed, so i suppose it does effect speed.

Generally with fans, where not a great deal of torque is required to start, the capacitor is of a 'run' type, as opposed to a 'start capacitor'. If you check out the accompanying link, there might be some help there.
https://www.achrnews.com/articles/84931-the-motor-doctor-diagnoses-motor-capacitors
It's possible that your capacitor has shorted internally or if it's metal cased has grounded.
Rather than explain here, there's no shortage of Internet advice on testing capacitors and the precautions required when doing so.

 

[tona955]

Yeah, I have tested the cap and it does not hold charge compared to a hood one.
I just wanted to know if there was anyway of working out what size it ought to be in microFd.

 

[Seadog]

To repeat what carbon said, it's 25μF @ 400V

 

[tona955]

Okay, I have tried that and the speed is still not the normal speed

 

[carbon]

Then it doesn’t look good for the motor. Can you see the windings inside the terminal box? Do some look darker than others? If they do then would have thought the motors been run to long with a failing capacitor and overhead the windings. One way to check is to remove one end cover and check the cord that holds the windings in place, if it’s broken and melted then motors got to hot and needs replacing

 

[tona955]

Good plan, they look good within the terminal block and I will check the windings later today.
Thank you again for your support.