Do these motors still rotate freely when disconnected, without fan blades?
If they're getting noisy, the sleeve bearings may be failing faster than if
these motors were used in less severe indoor indoors.
I've seen considerable damage from sleeve bearing failures where the rotors
drag on the stator poles.

Enclosed motors would very likely last much longer.

TEFC totally enclosed motors are available, and typically have ball
bearings, so they wouldn't be affected by shaft rust from humidity, or dust
wicking the oil out of the bearings.

--
WB
..........


"Bob S" wrote in message
...

I have a greenhouse with three fans from "American CoolAir".

The problem is that the motors keep failing. At the moment two are
running ridiculously slowly when powered on high speed. The other will
start and run on high speed, but bangs on startup at low speed; it is
as though the starter is kicking in and out.

The company keeps sending replacements, but I would rather have motors
that didn't need replacing. Is it possible to get drop-in replacement
motors that would actually work more-or-less forever?

The environment is not the greatest, with humid air blowing over them
in summer and the motors in cold air and being frozen in winter, but I
have had other appliances in similar conditions that never suffered a
motor failure.


The motor name labels say

Emerson

Model S63ZZJKW-7333

HP 1/2 RPM 1725/1140 SF 1.3

V 115 Hz 60 PH 1 Code L

A 7.2 SFA 9.5 AMB 40C

Made in Mexico



It looks just like the one in this pictu

http://www.federalindustrialsales.co...ph/m1-318.html

I have been through about 7 motors in the past couple years