HVAC Blower seizes(?) with power

Old 08-29-16, 05:12 PM
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HVAC Blower seizes(?) with power

I'm a DIYer that isn't overly technically, but can google, search, and fumble my way to fix just about anything, so bear with me as I may use some incorrect terminology.

The blower in my HVAC system isn't running properly. The outside AC unit and the inside furnace cool and heat properly and come on appropriately for Cool/Heat settings and don't come on otherwise. But the blower fan motor doesn't spin. While the power is off, the fan can be easily spun by hand. When the thermostat is switched to "On", the blower motor makes a very loud buzzing sound (not humming) and the fan is only moveable with a strong amount of force. I replaced the capacitor, and nothing changed.

This happened after a big storm in which the power went out. Checked breakers and everything is fine there, but I thought this might be good backstory to jog someone to say "well you could have burned out XYZ in a surge."

What else can I check/replace before I replace the whole motor? Do I need to check every wire? What causes a motor/fan to seize when power is applied but spins freely when there is no power?

Thanks in advance!
Old 08-30-16, 05:27 AM
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Do you know what type of blower motor is used in your furnace (ECM or PSC)? If not, please post the full make/model number of the furnace so we can try to find some info on it. ECM motors have a control module (electronics) attached to the back of the motor. An ECM motor would be much more susceptible to being damaged by a lightning strike than would be a PSC motor.

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