In a hot location, the surrounding air increases a motor’s normal running temperature. If the motor is loaded near its capacity, it will overheat. Even forced ventilation may not help.
If a motor is located too close to a wall or if anything impedes its intake or exhaust airflow, it can overheat (depending on ambient temperature). The recommended clearance is 18 inches on all sides.
Intense sunlight can cause a maximum-loaded motor (or a motor that starts frequently) to overheat.
An enclosure added for protection from the weather can be harmful to a motor, because air movement is restricted. In addition, the enclosure may trap the motor’s hot air exhaust. An exhaust fan is often added to remove the hot air from the enclosure. However, forced air movement shouldn’t affect the motor’s normal air movement.
Maintenance-Caused Overheating
Belts Too Tight
Extra stress is put on bearings if the belts are too tight. If the motor has a long stator, the shaft may bow and misalign the bearing’s inner race. There have been cases where the rotor dragged on the stator core (because of overly tightened belts).
Pulley Problems
A replacement pulley that is slightly larger than the original can overload a motor if the load increases with a speed increase.
A worn pulley may make it necessary to tighten the v-belts excessively (to keep them from slipping). (The motor drive pulley is always the one that wears first.)