An inspection of a blower motor should cover two major questions. First, is the blower wheel clean? Second, are the air holes on the motor clean so the motor can cool itself?

Cleaning the blower wheel is a snap. Pull out the blower tray and clean with a light brush.

Secondly the blower wheel needs to be cleaned so that the furnace can move enough air to cool itself. A furnace is designed to run within a certain temperature range. When the furnace runs outside of it's temperature range, (overheats) a safety circuit will shut it down. If the furnace is not releasing the heat that was created while burning fuel, then that heat is not being used to heat the home. The unit is running inefficiently. If the blower wheel is dirty, the air flow will be reduced.  This will cause the temperature inside the furnace to rise. The furnace will overheat and shut down. 

Second, is cleaning the blower motor. When the motor is running, heat is created in the windings. The motor has holes on the ends of it to draw air in. This will allow the motor to cool itself while it is running. If these holes are blocked, the motor will overheat constantly. The result will be premature failure and inadequate heating. To clean these air passages, simply wipe them with a light brush when the power is turned off.