The furnace is responsible for generating heat, but the blower system is responsible for distributing the heat throughout your home. Therefore, if the blower system of the furnace stops functioning, it can render a good furnace pretty much useless because the generated heat will never get where it needs to be. Of all of the HVAC complaints residential customers call a furnace repair company to help with, blower problems are one of the most common.
Thankfully, problems with a furnace's blower system are usually fairly easy to diagnose. Take a look at some of the common problems with how a furnace blower is functioning and the likely cause behind the issue.
The blower is not distributing any airflow at all.
If the blower is not sending through any heat when you know the furnace is on and generating heat, you probably have a completely failed blower motor. This failure happens for a few reasons. It can happen due to faulty wiring that is not allowing the power to get to the motor, or it can happen if the blower motor locks up completely. In either case, the motor will not come back to life; it will likely have to be replaced with a new unit.
The blower is only blowing heat intermittently.
You turn on the furnace and hear it kick on, and you also hear the blower system kick in as well. However, shortly after you hear the initial startup of the system, you notice there is no heat coming through the vents, but then the heat flow kicks back on again. Intermittent airflow through the heating system is a sign of an ailing blower system that is only working part of the time. Sometimes, before a blower motor fails completely, it will almost sputter, or work here and there.
The blower is making rattling noises and not blowing much heat.
The furnace comes on as usual, and you hear the blower system start up as it always does, but there are extra noises there that the system shouldn't be making: rattling noises. If the fans inside of the blower get warped or damaged, they can knock against the housing of the blower unit, which will cause the blower to make noises either constantly or intermittently. If the fan is damaged beyond repair, you will likely have to have the entire blower system replaced by a furnace repair professional.