Safety is very important. The control module and blower motor are electric. There is a control module and a transformer where voltage and current are normally present. Care must be taken to avoid bumping any adjustments for gas metering and over-temperature cutout. The edges of sheet metal are sharp. Hand protection is highly recommended.
If you feel you are capable of cleaning your own, you can save money that you would otherwise spend for a technician to make a house call.
For this, you will want:
a. a vacuum
b. an extension hose
c. a crevice tool
d. a dusting poof
e. work gloves (cotton is fine, leather is acceptable)
Step 1: Before You Begin
You will want to locate your thermostat and the power outlet that feeds your furnace. Your thermostat may be an analog type or it may be digital. Mine is digital. In the photo, you can see where the off switch is located. If yours is analog, there may be a switch along the outside edge. If not, turn the temperate setting to the lowest possible. You may also want to remove the fuse or turn off the circuit breaker in your home's electric box. You might also or alternatively unplug the power going into the furnace itself.
Step 2: Start With the Exterior
Step 3: Open Up
Removing the accumulated debris internally, the risk of fire is reduced and sensors may read with more accuracy. Moving parts will experience less friction, slightly increasing efficiency.
Step 4: The Lower Portion
The blower is a squirrel cage design. Air comes in the sides near the shaft and exits radially, funneled upward by the blower cover design. Debris in the lower area can work its way into and around the shaft and bearings. Chunks of dust bunny may get sucked in then pass through the airway system and get blown out into another room.
The module has electronic components such as relays, transistors, resistors, diodes, and so forth. When vacuuming the module, be careful not to bump any of the components with the tip of the crevice tool. If any of the electronic components get bent and make contact with other components, a short circuit condition could render the module non-functional.
Step 5: The Filters
Filters are made from a cardboard frame which supports a mesh of woven fibers or porous paper. The denser the weave and smaller the pores, the finer the particles which are blocked but this also reduces the time that the filter is useful. The more particles trapped in the filter, the less air that will flow through the rest of the system.
Gently vacuum your filter or replace it.
A clean furnace is a happy furnace!