One part you can expect to replace during the life of your furnace is the blower motor. The blower is what circulates the heat around and is continuously working. A few basic tips can make it easier to replace the blower on your own instead of waiting in a long waiting list for a repair person.
What You Need to Know about Blowers
Most blowers are standard, which makes them easier to replace. They are 5 5/8 inches in diameter and are called the standard 48 frame. You can also find 56 frame blowers and these motors have a 6-inch diameter.
Horsepower is something you will have to consider when you purchase a new blower. Common sizes include the 1/8th, 1/6th, 1/5th, and 1/3rd. These are the ones you will see most often.
RPMs are something else you will need to know for replacement. Common sizes are 1200 RPM and 900 RPM. Another well-known size is the 1550 RPM and is larger than the other two. Most blowers are single speed, but you will see ones up to four speed occasionally.
Three speed blowers are used as direct drives with a low speed setting for heating and a high speed for cooling. Wiring is standard for almost all blowers to make it easier to replace. Black wires indicate high, white is common, yellow and blue are mediums, and red is low. The brown and brown with white tracer are for the run capacitor.
You have two options for bearing motors. The sleeve bearings last a long time, but the ball bearings are better because they can last the life of the furnace. If the motor will run constantly, ball bearings are the better choice. With sleeve bearings, you can remove them and oil the motor as needed.
When you look for a replacement, make sure you don't choose a lower horsepower than the one you had. However, you also don't need to go to a higher horsepower or you will be wasting energy. Outdoor blowers are generally sealed and indoor blowers are usually open. The open blowers often have a higher rating, too.
To Do the Replacement
To replace the motor, you will need to shut off the electric to the furnace and cut the wires to the blower motor. Unbolt it from the furnace and remove it. If an electrical box is between you and the motor, you will have to move it out of the way. Clean out the area before installing the new blower. Take pictures or notes of how everything looked as you took it out so that you can put the new one back the same way. Connect the wires on the new blower and turn the electricity back on to test the unit.
If you do not feel comfortable making your own blower repair, you can contact a furnace technician to handle the job for you. They will install the new blower quickly so that you will not be without heat any longer than necessary.