Regardless of the season, you rely on your HVAC system for comfort. In winter, you use your furnace to keep your home warm. In summer, you crank up your air conditioner to avoid high indoor temperatures. Although these two appliances in your HVAC system serve entirely different purposes, they use the same device to operate: your blower motor. However, since your blower motor is used nearly all year, it will become dirty and reduce your HVAC system's efficiency and air quality. Since your blower motor is a large centrifugal fan, you can prevent these problems from occurring by following these four steps:
Remove Your Blower Assembly
Shut off the power to your HVAC system and locate your blower compartment—which will either be above or below your furnace unit. Remove the access panel from your blower compartment and inspect the electrical wiring between your motor and HVAC system. The wires between your motor and control panel are connected by clips or wire caps. Pull the clips apart or untwist the wire caps to break the connections. If you're not familiar with the function of each wire, then label each connection with a numbered piece of tape to ensure proper reinstallation.
Once your wiring is disconnected, inspect the mounting hardware between your blower compartment and assembly. Typically, blower assemblies are attached by a pair of guide rails. In such a case, remove the two bolts or screws at the end of your rails and pull your blower assembly out of its compartment. However, if your blower is held in place by multiple mounting screws, then remove the screws and lift your assembly out of its housing.
Disassemble Your Blower
Now that your blower assembly is out of its compartment, you can easily disassemble it and separate its various components. To begin the disassembly process, remove the fasteners on the deflector plate near the air intake manifold (the large opening in the side of your assembly) and pull out your deflector plate. Use a ratchet and socket to remove the middle nut from the center of your blower's fan wheel.
With both these components removed, you can flip over your blower assembly and use your ratchet to remove the three or four bolts connecting your motor to your blower assembly. However, while removing your motor, be careful with the remaining electrical wiring—if you put too much tension on the wiring, you're likely to break an essential connection.
Your fan wheel can now be pulled out of your blower assembly. However, before removing your fan wheel, take note of which way your wheel is positioned. One side of your wheel will have a concave center, and the other side will have a convex center. These sides must face the same way inside your blower assembly upon reinstallation. Otherwise, your fan wheel will reverse the airflow through your HVAC system--which can result in serious damage to your furnace and air conditioner.
Clean Your Fan Wheel and Motor
During operation, debris that slips through your air filter or unsealed gaps of your blower housing will settle on your fan wheel's blades. When this happens, the amount of space between each blade will be minimized—which results in decreased airflow. Additionally, debris that's pulled off your wheel's blades and into your furnace will produce foul odors when ignited.
To clean the debris off your fan wheel, place your wheel in your yard and spray each blade with your garden hose. If any stubborn debris remains on your blades, then either apply a degreasing agent or manually scrub the debris with a brush.
To remove debris from your motor, wipe the external surfaces of your motor with an old rag or towel. Use an air compressor or gas duster to blast debris out of the internal electronics. By cleaning the internal electronics, you can prevent your motor from overheating during long periods of use.
With your wheel and motor now clean, reassemble your blower by placing your fan wheel inside the assembly in its original direction. Slide your blower motor through the center bolt hole of your fan wheel and reinstall your motor's mounting screws. Center your fan wheel inside your assembly so that neither side of the wheel makes contact with walls of its housing before reinstalling the center bolt. Once your wheel is centered and secured, reinstall your deflector plate.
Reinstall and Test Your Blower
Place your blower motor back into its compartment and reinstall any mounting fasteners. Reconnect the wiring between your system's control panel and your blower before restoring your system's power. Activate your system and test your blower motor at each of its various speeds before closing your access panel.
If you encounter any problems while removing, cleaning, or reinstalling your blower, then contact a professional HVAC services technician. If you continue attempting to service your blower assembly without knowing exactly what to do, you're likely to cause accidental damage that may ruin your motor.