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What Happens When You Don’t Change The AC Filter

Filters become a low priority due to a misunderstanding of what they actually do. Standard HVAC filters are not intended to purify the air you breathe but protect the unit itself. Filters do trap some dust that gets sucked into the ducts, but most filters aren’t fine enough to trap pollen, dander, particulates and other allergens.

Note: There are higher efficiency HVAC filters that are designed to remove allergens, bacteria, mold, and even viruses.

Buildup on blower fans and ductwork

Filters fill up with captured dust and dirt. Depending on your system, you should either change your AC filter or clean it. Paper filters are disposable, with cardboard frames and a paper screen. Sturdier filters are reusable, usually with metal frames, and can be cleaned according to manufacturer instructions.

If you don’t change your AC filter, it will begin to fail and will no longer be able to filter the air properly, letting dust and contaminants get into the AC. Dust jams the moving parts of an AC such as fan motors and valves. Airflow is restricted which creates a strain on the system. Leading to poor efficiency and breakdowns.

Moisture and mold contamination

The only type of filters that catch allergens and spores are HEPA, made of a much finer mesh than other filters, and so can screen out tiny particles such as allergens, pollen, dander, and mold spores. They are categorized by MERV ratings 1 through 20. The higher the rating, the more effective it is at catching small particles.

IMPORTANT: Not every system can accommodate higher efficiency filters.

If you have a higher efficiency filter and fail to change the AC filter often enough, a buildup of moisture can cause mold to accumulate in the ducts, leading to serious mold infestations.

Wear and tear

The problem will get worse if you ignore it. The filter itself isn’t the only thing that will stop functioning. Dust in the ducts will degrade the moving parts, making them run slower and draw more power. This will wear out your AC much faster than normal. The average lifespan of an HVAC unit is 15-20. Without a regular filter change, it can be shortened by 5-10 years.

For more questions about filters or to schedule service, call 72 Degrees Comfort Company at 515-965-7272 or email us at

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