Start Run Motor Capacitor

[sstouk]

Hello guys,

I have an issue with a medical compressor not being able to restart the motor once the first pressure level is reached and motor stopped. After pressure level drops - engine used to re-start automatically but after a few years the power need to cycle on the compressor to make the motor work again (and then it repeats - motor never restarts automatically as it used to do before).

Manufacture suggested replacing a motor capacitor and sent a replacement.

The rating on currently installed capacitor is 22.5 uF and the replacement I got is rated 15 MFD (same voltage range)
I am hesitant to install it because I feel the difference is too big (over the 5% tolerance).
I sent my concern to manufacturer but I am being assured that the capacitor they sent me would be OK.
I'd like a second opinion on how dangerous it may be to replace a Start/Run motor capacitor with a smaller value because replacing the whole motor on this equipment will be quite expensive if it burns.
Thank you!

 

[Chemelec]

Yes it Will be OK to use it.
However since it is a LOWER Capacitance, You may Still lack the POWER on RE-Start.

 

[Bluejets]

Many compressors use an unloader valve. Best check this first if it has this arrangement fitted. Since you have had the compressor for a time, perhaps you are aware of a pressure release noise as the motor shuts off. This is the unloader.

 

[Tha fios agaibh]

I agree with you that it's too small. There isn't and real danger of installing it, other than it'll probably just burn out prematurely.
I try to be within 10% of start caps value.

It is wise to monitor start and run current. Your problem may be the compressor and not your motor.