We hope you’re reading this post because you have these questions on your mind—probably because you’ve seen mention on our site, or elsewhere on home service pages, that routine furnace filter changes are mandatory for top heating performance.
Yes, the air filter in your furnace must be changed regularly throughout the heating season. If your AC is housed in the same cabinet (and most are), then it shares use of the same filter and it needs to be routinely changed during the cooling season as well. Simple panel filters (which you can purchase in packs for about a dollar each) usually need to be replaced monthly, while stronger pleated filters can last from 3 to 4 months.