Motor cap for....a motor, question

[BillWojo]

So my girlfriend drops off this inflatable Easter bunny that she sets up in her yard every year and says it's not working. So I open up the squirrel cage housing to check it out.
Fan is tight to the shaft and spins free. Plug it in and it just vibrates, try to kick start it and it just slows down and stops. It has a start cap on the outside of the motor, 2uF 250VAC. Will a bad cap keep you from kick starting the motor or is the other winding burnt out?
The closest cap in the form factor that I could find on Ebay is a 3uF 250VAC. Will this work?
Here is a link. Motor Run Capacitor 3uF 250V AC ADM250A305J (1 piece) | eBay
Thanks

BillWojo

 

[PRR]

Some motors, you have to "kick" to nearly sync speed, 3600RPM in NJ. Maybe 3000RPM for a fan motor (typically never gets near sync speed). That may be more "kick" than you can manage by finger.

I would want to be closer than 3:2 on cap value, but time is short and this isn't a 365/year application. May be OK.

But if you have the wiring exposed, I'd say a buzzer or ohmmeter is in order. It sounds like you know what to expect.

 

[Elvee]

To determine where the problem actually is, disconnect the original cap and patch any ~2µF >100V cap (non-electrolytic obviously) instead.
Just make a few seconds try: if the motor starts normally, buy a suitable replacement cap, and if it stays stuck vibrating, assume the motor is cooked and bin the whole thing

 

[BillWojo]

I found a 2uF 250VAC cap on Ebay for 5 bucks and ordered it. Hopefully that takes care of the problem. I don't think it's a burn winding as there is no nasty smell coming from the motor. These things just sit most of the year and for a few weeks are pulled out and used. Tough life for any cap.

BillWojo

 

[Pano]

For future reference you can pick up caps like this - and also motor run - at just about any local HVAC store for good prices.

 

[BillWojo]

Thanks Pano. I installed the cap last Friday and it made no difference. Just sat there and vibrated. One of the windings must be bad.

BillWojo

 

[AndrewT]

There is some form of centrifugal switch inside that disconnects the motor start cap as it reaches some set point speed.
I wonder if the contacts in the switch are burned/permanently open.
This would leave the motor start cap unconnected and prevent the motor turning at first power on.

 

[Elvee]

2µF is motor-run (permanent), not motor-start. Start values are much higher, in the tens or even hundreds of µF's