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OT- A/C condenser fan issue

Cole2534

Diamond
Joined
Sep 10, 2010
Location
Oklahoma City, OK
Friend mentioned his A/C condenser fan wouldn't spin up. I figured it was a capacitor issue so I took a meter over and they all measured fine but it exhibited that locked rotor buzz when fired up. I tried to hand the prop the fan but it was stiff as hell. However, it spins freely with no current applied.

It reminded me of a stepper motor in a sense.

Any idea what'd cause this?

Programmed via Mazatrol
 

ratbldr427

Stainless
Joined
Mar 21, 2006
Location
jacksonville,fl.
If it's a vertical mount then the thrust washer and bearing may be worn and the rotor will drop when the power is off and jam when power is applied. Normally the rotor will pull to center when power is applied. I have had several fail that way, the thrust washer is Bakelite or Garolite and is not loaded when running but when power is off the rotor drops a small amount. I assume it is a squrrel cage motor?
 

texasgeartrain

Titanium
Joined
Feb 23, 2016
Location
Houston, TX
Replaced my daughter's a/c blower motor this past summer. A so called "smart motor" I believe. Has some sort of control module incorporated into it.

Be it a short in the module or motor I couldn't say. But when powered was applied the shaft didn't spin but appeared locked up, as if held by magnets, not mechanically froze. Power cut, you could spin it fine.

Long story short, I didn't dick around, a google/amazon search found me one on amazon for $185 if I recall. Replaced, and the new one worked perfect.
 

52 Ford

Stainless
Joined
May 20, 2021
The condenser is the outside unit. The compressor unit.

It's probably going to be an induction motor.

MY suggestion is to pull the motor off and investigate it. Remember - it's HVAC so you can probably take the whole unit apart with a 1/4" and 5/16" nut driver. :D

Anyway, pull it part and check the bearing surfaces. Might be worn and the rotor could be contacting the stator.

Unless there's some sort of funky wiring issue, it should be a fairly straightforward mechanical issue.

If you want, I can take one apart and post some pictures. I have a spare from a "full size" residential unit.
 

EPAIII

Diamond
Joined
Nov 23, 2003
Location
Beaumont, TX, USA
Bottom line, if

1. capacitor is OK
2. power gets to the motor
3. it does not run

REPLACE IT!

And a new capacitor is probably a good idea too.
 

crossthread

Titanium
Joined
Aug 5, 2004
Location
Richmond,VA,USA
When you say the capacitor is good, are you just measuring to see if it is shorted with an ohm meter? It really does sound like your cap is bad and it is very common. It's kind of the first thing to look for. I would replace it.
 

deltap

Cast Iron
Joined
Sep 3, 2004
Location
Wisconsin, USA
If it's a pac motor, definitely try a new cap before replacing the motor. Have you checked both start and run windings for continuity? The locked rotor condition sounds like it could be an open start winding.
 








 
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