Why would cause the home a/c fan unit to stop when it gets hot?

Question

Why would cause the home a/c fan unit to stop when it gets hot?

Answer 1

Bi Polar nailed the motors.  Old motors last so much longer then the new ones.

Answer 2

Not enough information...Is the thermostat satisfied? Is the motor over heating? Is there a cooling signal from the thermostat? That's what we get the big bucks for.

The condenser fan motor also has a capacitor that can be blown, and cause the motor to over heat.

Answer 3

Sounds like the unit is shutting down on heater switches. These heat activated switches are built into the motor winding and are not serviceable. Something is causing the motor to work too hard or it is nearing failure. A service tech is needed to find out what is going on.

Answer 4

They have an overload which shuts down the motor if it gets hot. The motor has a bearing mounted in either endbell. This bearing has a cotton well wrapped around it that is filled with high temperature resistant oil. The cotton contains the lubricant that seeps into the bearing and forms a slick barrier between the shaft and the bearing. The oil drys out and metal to metal friction causes heat to build up in the motor. The dry bearings begin to drag down the motor. As the bearings wear they begin to allow for the rotor to rub against the stator. The resulting heat generated overloads the motor protector and kills the power to the motor before the windings are harmed. At this point the tech attempts to add a lubricant to refill the cotton wells and hopefully save this motor. Most of the time the motor gets replaced. Years ago they used to repair the motors by replacing the bearings with new sleeve bearings. Newer motors cost less than paying for motor rebuilds so the motor rewinders of the past became nonexistent. With the advent of cheaper labor overseas and cheaper materials and nobody regulating these poor quality motors, I expect you will be replacing motors at a faster pace than ever.