04/27/2023
CENTRAL AIR CONDITIONING MOTORS PART 1
Condenser Fan Motors:
Direct Drive fan motors are generally used in the outdoor condensing units. They are used in home and commercial units and are found in 230 volt single phase for home use and 460 volt single phase and three phase for commercial and institutional use.
These motors are sealed on the end that mounts or can be sealed on both ends. They are generally available in 60°c and 70°c ambient ratings and use sleeve or ball bearings. Given the choice, 70°c ball bearing motors are preferable. These motors usually have drain (weep) holes. The drain holes are at the bottom and when the motor is mounted the drain holes should be open (plugs removed). The totally enclosed motors are classed as semi-cooled containers as they are exposed to temperatures above and below dew point and condensation will build up inside the motor. Unless drains are provided the motor will fill up with water.
If you have to move a motor with ball bearings it should not be lifted by the leads just as if you have to move one with sleeve bearings you don'ht want to lift it by the shaft. When a single phase permanent capacitor motor is replaced, the capacitor should also be replaced or at the very least tested.
CAUTION: Horse Power requirements change as the cube of fan speed changes. A 10% increase in fan speed requires a 33% increase in motor horse power (HP). So do not replace an 875 RPM motor with a 1075 RPM motor. Stay tuned for part 2 - as we move into the hotter time of year please know we stock a wide range of HVAC motors to keep you and your family cool!
