Make blower maintenance part of your seasonal tune-up schedule -- and check out the unit whenever air seems to be moving faster or slower than usual.
Some blowers have direct-drive motors; others operate with an adjustable V-belt-and-pulley setup. You needn't worry about adjusting the direct-drive type, but it may need oil, so check the manufacturer's instructions.
On either type, look for lubrication ports on the motor and on the blower pulley on belt-drive units. With an oil can, squirt a few drops of SAE-10 nondetergent oil into these ports at the beginning of each heating and cooling season.
Belt-drive blowers require the correct belt tension. Check the belt for fraying, cracks, and signs of wear -- consider keeping a spare one on hand. An adjustable motor pulley lets you change the speed of a belt-drive model by loosening a setscrew and adjusting the distance between pulley faces.
If a motor has oil ports, they'll be at each end of the shaft. Also, check for lube points on the blower fan.
Adjust the belt so it is loose without slipping; it should depress about one inch. Keep mounting bolts tight.