Hi, I am replacing a fan blower motor and having some troubles.

I mounted a new motor to an old housing, and when I give it a power it starts strong and seems fine, but after about a minute it starts to slow down. The amperage draw is about 4.5a on the high speed wire (black) and it stays between 4.1-4.6a even if it slows down. I turn the motor off when it slows down, because I'm afraid I might burn the motor off.

Checked the resistance between white to black (11.5 ohms), white to blue (26 ohms), white to red (29 ohms), white to brown (100.5 ohms), black to red (38 ohms) black to blue (15 ohms). There were no continuity between the leads and the body of the motor. The motor seems fine.

Capacitor is brand new. MFD matches to the motor requirement. My multi-meter doesn't measure MFD, but when I checked with ohm meter setting the numbers go up and quickly come back down to zero. Seems okay too.

Now I think this might be the cause of the problem. When I turn the fan by hand it turns nice and quiet. But when I give it a power, it makes some sound. It's not grinding against anything, but maybe the fan is not aligned properly. Maybe because of that the motor is vibrating too much and slows down?

Is there a way to align it properly and reduce the vibration?
I haven't tried running the motor without any load.
I give it a try later and update it here.

What else could be the problem?



Any kind of input would be much appreciated!


***UPDATE***
Motor works fine without any load. I'm guessing, I didn't build the frame around properly.



Motor specification:
A.O. Smith (now Century) - DE2E220 1/8 HP, 115 Volts, 60 Hz, 1 Phase, 1625/3 SPD RPM
Direct Drive Blower Motor, PSC, 1/8 HP, 1625 RPM - 3 Speed, 115 Volts, 1.9- 0.94- 0.56 Amps, 5 Motor Diameter, Shaft Dimension: 1/2 x 5-3/4, Enclosure: Open, Sleeve Bearing