Page 216

NORA Oilheat Technicians Manual

Diagnosing motor troubles Typical heating system motors are reliable, but problems can occur. The following should help you quickly pin point a problem. For more details, see Chart on page 10-16. Motor Trouble Check List 1. The motor will not start a. Is voltage present at the motor? Is it the correct voltage? (It must be within 10% of nameplate.) Are all wiring connections tight? b. Is the motor off due to overload? If manual reset, push the button. If auto, wait for the motor to cool until it resets. c. Is the capacitor (if needed) functioning? If in doubt, replace it with a capacitor of the same rating. d. Is the load on the motor excessive? If the motor starts after the load is removed, this could be the problem. e. Are the bearings on the motor seized or dry? If so, free up and lubricate. 2. Noises a. Is motor lubricated? If not, do so, unless it is permanently lubricated. b. Is the alignment of the motor shaft and the driven device correct? c. On a belted unit, is the belt OK? Is it too tight or too loose? The belt should have a 1" play. d. Noise could be caused by shaft end-play (the distance the shaft will move in and out of the motor). A new motor will have no more than .035" of movement. If the shaft end play is more than .060", the motor could be suspect. 3. Motor overheats a. Is there adequate ventilation? Are the air venting slots on the motor clean and unobstructed? b. Is the load excessive? Use an ammeter to measure the current draw. If the load or the draw is more than the nameplate rating, the load must be either reduced or a larger more powerful motor must be installed. Make sure that the driven device is unrestricted in its operation. NOTE: When checking the current draw of the motor, the service factors must be considered. A motor with an amp rating of 4.0 and a service factor of 1.25 can safely be operated at 5 amps. c. Is the motor located in an excessively hot area? Chapter 10 Motors 10-10 Motors


NORA Oilheat Technicians Manual
To see the actual publication please follow the link above