It might be an unassuming and easily-overlooked part of your home HVAC system, but your furnace or air conditioner’s air filter actually plays a big role. It keeps the inner workings of your system free from dust and debris – and when it clogs up, the strain it puts on the fan motors can be one of the leading causes of system failure. Savvy homeowners know to replace the filter once a month, and here are some of the tips they may use to remind themselves to do it.