He is incorrect. It will not make it 'run better'. If anything, it will run less efficiently but the difference will likely be negligible. The main concern is that when this 7.5 fails and the next guy comes and says 'well, i don't have a 7.5 but i have a 10. close enough.' the issue can be compounded. I think that if you already paid for the 7.5 you probably wont have any issues, even though it is technically wrong. I might get yelled at for saying this but i would just let it go. good luck.

 

well, if it doesnt blow anything up, i guess i'm fine with it. he did leave the original capacitor, so i'll just keep that near the furnace in case it happens again. btw, is uf and mfd the same thing?

thanks for the answer ADillon

 

I keep 5's on the truck but have seen this done many times and doesn't seem to hurt anything.

 

The maker of your blower motor says use a 5 and then I would ask the service man to come back and put the right one in.

 

Tends to shorten the life span of the motor. Its your money, leave it in if you want. but motors aren't real cheap.

 

What a hack, call them back out and put a 5MFD in. You paid them to do a correct job.

STUD

 

U

 

it's not Uf, it's the greek symbol for micro... looks very similar to a u but it's an µ
and yes, µf means microfarad
motor capacitance determines the shift for motor torque, and the field is wound for a specific value. +/- 10% I think... so if it calls for a 5, it needs a 5 MAYBE a strong 5 would work, but a 7.5 will cook the motor in short order.