A furnace tune up or furnace maintenance is a safety and performance check up on your furnace. The manufacturer of your furnace will void the warranties on the furnace if the furnace is not maintained properly. The reason for this is because the vast majority of system breakdowns occur due to lack of maintenace.
If the furnace is not properly maintained dirt and debris get everywhere in it and they can certainly cause many problems.
Dirt in the Filter: A dirty filter causes a reduction in the airflow across the heat exchanger and this increases the temperature of the heat exchanger leading to premature failure. This causes increases in utility bills, poor heating performance and unhealthy living conditions.
Dirt in the Blower Motor: Dirt lodged in the windings of the blower motor can cause bearing failure and overheating. This leads to premature failure.
Dirt in the Blower Wheel: Dirt buildup on the blades of the blower allow for less restrictive wheel movement and increased rpms. This increase can cause premature motor failure. The dirt also prevents the blower wheel from capturing and projecting air through the furnace and across the heat exchanger. Higher temperatures in the heat exchanger can cause premature failure, poor heating and high utility bills.
Dirt on the Heat Exchanger: Dirt on the heat burns when the furnace fires up. This is that smell you have when you first start up an old furnace during the heating season.
Dirt in the Ducting: Once dirt enters the ducting it can become lodged and periodically come loose acting like a continuous dust spreader across your electronics and furniture in your home. It leaves black and brown streaks by the registers.