Exhaust motor going on and off

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mtnelectrical

Senior Member
I installed a commercial exhaust fan for a small restaurant/bar a few months ago. Owner called me and said that the exhaust motor goes on for 20 seconds and then goes off for 2 minutes or so. Motor is 3/4 HP 120v. I'm guessing the capacitor is defective. Is there a way to check the capacitor? Thanks for your responses
 

Twoskinsoneman

Senior Member
Location
West Virginia, USA NEC: 2020
Occupation
Facility Senior Electrician
fluke-179-imsk-industrial-combo-kit-meter.jpg


one of these have always worked for me...
 

mike7330

Senior Member
Location
North America
Check your running amps, if it to high, check to make sure the pulleys are still set to specs. The motor could be overloaded if the pulleys are set wrong or are the wrong size
 

ActionDave

Chief Moderator
Staff member
Location
Durango, CO, 10 h 20 min from the winged horses.
Occupation
Licensed Electrician
Yes. The motor needs the capacitor to give it a kick to get started so if the capacitor is bad either it blows or the motor burns up.

Like Mike said the best thing to check is amps. I would check with the belt off first and then with it on.
 

Joethemechanic

Senior Member
Location
Hazleton Pa
Occupation
Electro-Mechanical Technician. Industrial machinery
You might find that the blower shaft isn't turning freely. That might be what caused the original motor to fail. You should be able to give the blower a spin by hand and it should freewheel.
 
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