Here are a couple of issues that may cause your furnace to fail in the winter
Wear and Tear
If you are running your furnace all winter, usual wear and tear is expected. Strain on the belts and bearings can cause the furnace to overheat and malfunctions with the fan motors can cause air flow issues.
Dirt and bacteria can build up and cause air flow issues within your heating system. Make sure you replace the air filter monthly.
An annual furnace check up helps your system run more efficiently and can lengthen the life of the furnace. Catching small problems before they become big problems can safe money.