If you have an E.A.C. (electronic air cleaner) on your furnace you need to remove the small (about 8" wide) door from the EAC. You will then find (unless they’ve neen lost) a metal mesh pre-filter (or 2) on the side of the EAC which is farthest from the furnace. Remove the pre-filter(s) and wash them, dry them, and replace. If you lack pre-filters they can be ordered from the EAC manufacturer. Good luck.
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if its electronic the popping sound would be normal, and if it has a fiber filter, 99% of the time its located very near the furnace.
If you have an E.A.C. (electronic air cleaner) on your furnace you need to remove the small (about 8" wide) door from the EAC. You will then find (unless they’ve neen lost) a metal mesh pre-filter (or 2) on the side of the EAC which is farthest from the furnace. Remove the pre-filter(s) and wash them, dry them, and replace. If you lack pre-filters they can be ordered from the EAC manufacturer. Good luck.