The Home Furnace Blower Spins Too Slow

Sizing

• If you have just bought a new furnace, or if you have moved into a house that has a furnace that was previously installed, you may have a sizing issue. If the furnace is too small for the house or if the ductwork is too large, the fan may be operating at normal speeds but does not produce enough air to move the air properly. Access your air vent through your furnace panel to determine whether the fan blades turn easily. If they do, the problem may be the furnace or its ducts. Clogged vent filters may also be responsible for the problem.

Dirt Problems

• If your blower system has encountered a lot of dust, it could be slightly jammed. Dust can create extra friction that slows the blades and the crankshaft your furnace uses, not to mention causing the clogged filter problems already mentioned. Wipe down your fan, the surrounding vents and the fan framework to remove any lingering dust or grease.

Fan Issues

• The issue may be with the fan itself. Check the fan for any warped blades or damaged framework. If the fan has become misaligned, it will not turn properly and will slow down air flow. Fixing this problem requires replacing the fan. You may be able to rebolt the fan in place to fix minor issues. This problem is often accompanied by noise that lets you know something is wrong with the blades themselves.

Motor

• If the fan is spinning very slowly, the problem may be the motor. A stuck motor or a motor ready to burn out may spin too slowly to properly turn the fan. You should check the fan belt too. The belt can become worn out, dirty, and may lose its lubrication. If both the fan and the motor are working properly, replacing the belt may solve your problem.