1. Disconnect the power supply.
2. Disconnect the fan motor wires from the unit.
3. Set the ohmmeter to the RX1 scale and zero it.
4. Connect each probe to a fan motor terminal. The meter should register a continuity reading. If not, the motor is defective and must be replaced.
In the case of capacitor-run or capacitor-run-capacitor-start fan motors in commercial units, the problem can also be due to a defective capacitor in which case the capacitor will have to be checked. (See the pages about Capacitors.)
a. Sometimes the blade must be removed before removing the motor. Hold the blade with one hand and, with a nut driver or a pair of pliers, remove the stamped nut and gently remove the blade. Note the pitch of the blade. If it is remounted backward on the new motor, it will move the air in the wrong direction.
b. Remove the motor and its bracket by removing the screws connecting the bracket to the refrigeration unit.
c. Remove the bracket from the defective motor (see fig. 58).
d. Mount the bracket to the new motor in the same location it was on the old motor.
e. Mount the fan blade to the new motor ensuring that its pitch is in the same direction as on the old motor.
f. Install the assembly, reconnect the wires and, replace the cover panel.
When replacing condenser or evaporator fan motors in commercial refrigeration units, always pay close attention to the watt rating of the motor to be replaced. The new fan must have at least the same The new fan must have at least the same wattage and revolution per minute. A fan motor with lower revolution per minute turns slower, causing a considerable loss in the efficiency of the evaporator or the condenser. Consequently reducing the efficiency of the unit.
Fan motors do not usually come with blades. Buying them separately will facilitate getting an exact match for the replacement. An instruction sheet is included with the new motor. Before removing the old fan, note the direction of the motor rotation and the angle of the blade. Incorrect assembly changes the direction of the airflow, causing the unit to malfunction.