Field noteHeating & Cooling
A 30 HP fan motor: slipping pulley, misaligned bearing and coil cleaning
A service call on a large air-handling unit driven by a 30 HP fan motor: the pulley had slipped, a bearing was found misaligned, and the evaporator coil was cleaned on the same visit. The photos show the drive, the motor and the coil after cleaning. The technician's findings will be added when supplied.
The drive
A 30 HP motor drives the fan through V-belts and a pulley. On this call the pulley had slipped; the first photo shows the drive with the old belts off.
The bearing
The bearing on the fan motor was found misaligned. A misaligned bearing wears the belts unevenly, runs hot and shortens the life of the motor.
The coil
The evaporator coil was cleaned on the same visit. A dirty coil cuts airflow and the unit's capacity. After cleaning, water runs off the face of the coil and the fins show clean, as in the photo. Our maintenance plan schedules coil cleaning as a separate service day; on this call it was combined with the drive work.
Questions
How often are belts and bearings checked?
On every maintenance visit. Belts, bearings and the blower are on our checklist for rooftop units and air handlers, and a filter-and-belt visit between seasons is part of the plan for most sites.