Need some educating

This was a 18 year old Ruud furnace. Could someone explain the box and what appears to be a power pack that is located in front of the blower.



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That would appear to be a motor run or start capacitor that has been replaced and not mounted correctly. Defer it and move on. :wink:

That is a run capacitor.
It is excessively large for the application but it’s okay to run an oversize capacitor if the mf capacity is correct.
The capacitor should be properly secured to the frame of the unit or fan housing. Vibration will cause the casing to leak and explode.

I would recommend that the installer/repair person come back and install it correctly at no cost to anyone.

David, how can you tell if a it’s run or start?

A start capacitor is made out of Bakelite (a substance dark in color).
A start capacitor is round.
You need a potential relay to take a start capacitor out of the system as the motor achieves full speed. This is a square looking device in most cases. It is labeled 5, 2, 1. You can also have a potential relay installed on top of a start capacitor as a hard start Kit that runs in parallel with a run capacitor.
A run capacitor is metallic in color, generally are oval (there are round run capacitors however).

A start capacitor is seldom needed on a blower motor for a residential application. You will only find a start capacitor on the compressor circuit. A start capacitor gives the motor it is attached to a swift kick in the butt to get started and must fall out when the motor reaches full speed/capacity. If it does not, it will burn out.

Thank you David. I’m very familiar with motors that have an integral centrifugal switch.