Bad condenser fan motor... I guess?

[RedBKM]

Wife calls today and says "It's 80 inside and the thing outside sounds funny".

Cap checks good (replaced in 2012) and contactor is good. I pulled the disconnect and let it sit for an hour or two. Came back and it took off like a new one for about 30 minutes. I heard the buzzing and found a blazing hot unit, no fan running. I thought the high pressure switch would shut off the compressor but thats another story.

Checking the fan (Red lead, Brown lead, Black lead) I measure 1.1ohms, 76ohms, 76ohms.

The 76ohms eventually dropped to 50ohms. Is this change due to the internal thermal protection?

The fan shroud was blazing hot so I'm figuring a bad bearing causing overheating? Thank God it was only 79 here in Virginia today!

 

[acmikee]

replace it and the cap. check your amps theyre probably high. pull your blade off first to make sure you can get it off before or it could be another trip to the store....

 

[Highbeam]

Resistance of "things" change with temperature. Could have just been that the wires were hot and not some sort of intentional protection.

 

[JerryC]

It sounds like you know what you doing, but I'll throw this out just in case you missed it.

My system did that as well, it was the coils being dirty and restricting the airflow enough that fan motor overheated.

At first blush that didn't make sense as the fan was pulling air and the system was cooling and later the fan would stop.

 

[RedBKM]

Seems to be going OK. Its been running about 3 hours and the house is now at temperature. New fan is nearly silent compared to the old.

On a side note the resistance on this motor is also 50 ohms but it doesn't go up like the old motor. I also replaced the contactor because it was original to the unit circa 2003.