Furnace Repair - How to Troubleshoot the Blower on a Hot Air Furnace

The furnace is hot and every once in a while the burner will come on for a short time and then go off again. But the blower that should be running to circulate the hot air from the furnace to the house is not working. How can you fix that? It really isn't very hard.

It does not matter what the fuel of your hot air furnace is. If the blower is not circulating the air through the heater then you are not getting warm. The function of the blower is to move the heat from the heater to the space that need to be heated.

A few simple tests can tell you what your problem is. Do you have power going to the motor that runs the blower? If you have power going to the motor and it is very hot than maybe the blower wheel has come lose and it is stuck on something that is keeping it from turning. Try to turn the wheel to see if it is stuck. If the wheel is not hitting anything and just turns hard then the bearings of the motor are bad and the motor needs to be replaced. In some rare cases the motor has little tubes to the bearings and some oil can be worked into the bearings to free them up. This is a long a tedious process, but I have done it successfully a few times.

If the wheel is hitting something, then try to see if it can be fixed. Sometimes the set screw will just come lose from the shaft and repositioning the wheel and tightening the screw will fix the problem.

Sometimes power will be going to the motor and nothing at all is happening. Replacing the motor is then the only option. The worst case that happens and is one of the most common problems is for the hub of the blower wheel to brake off. This lets the inside of the wheel fall down on the motor shaft. The metal from the wheel will saw off the shaft of the motor rather quickly as it is spinning trying to run the blower. The result of this is a ruined wheel and motor.

This gives a brief overview of some of the many things that may happen to your blower in your hot air furnace. I have encountered many other things over the years, but these are the most common problems. It will give you a few things to look for if you are having problems. Be very careful because many times the edges of the metal pieces are very sharp. You can be cut very easily when checking or handling these parts. I know and have the scars to prove it! Do not be in a hurry and be safe.