Small motor overheat

on HVAC evap fan motor

at 120 Vac no load motor overheat then feedback pulse stop working

5178 pulses / min divided by 4 = 1294.5 rpm shall turn at 1350 + - 20 rpm

what make the motor to overheat ?

the unit had a power surge when lightning

can it be saved ?

Picture of Small motor overheat
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jma123 (author) 6 years ago
# 12 is best answer
iceng6 years ago
Answering the heating portion.
This is a fan motor and when used as designed, it funnels some air
across the motor body, enough to cool it so it can run longer then 12min.

Japanese are savvy motor engineers and know a motor design is
cheaper if you use less copper and iron which makes it run hot without
the surmised cooling airflow.

As far as taking the motor apart, could it be done with a pin wrench ?
jma123 (author)  iceng6 years ago
I did pry out metal cap at the sensor end and stuff came out

look like a Hall sensor feedback ? but not sure

metal ring look smooth ? must have magnetic parts into it to generate pulses
?? I get 4 pulses per rev

see pictures enclosed

This is it good for a throphe or garbage

iceng jma1236 years ago
Right you are, try a paper clip, compass or  Magne-View Film to confirm
there are magnetic poles on the shaft ring where the sensor sits.
jma123 (author) 6 years ago
To Iceng & Steve



Without the starting cap, its not likely to reach synchronous speed, so the rotor lags too much behind the field in the stator, and overheats.

+1 is the very unofficial method we use to approve an answer from someone
It HAS to have a capacitor, probably 2uF or so between the heavy black and white wires, and power applied between red and black.

This is it is the beastie is it ?

Does it smell burned at all ? There doesn't look like any obvious way in

When you tested it, did you use a capacitor ?