You should replace your air conditioner filter approximately every 90 days, if you don't have allergies. However, AC professionals generally recommend changing it every 45 days for maximum efficiency. Be sure to replace it with the correct size and type of air filter. If your air conditioner is working properly, you can remove the filter and buy one that is identical to it.
In general, most air filter manufacturers and HVAC companies suggest changing your air filter every 90 days or 3 months. This may vary depending on the location of your home (e.g. dry and dusty climates), if you have pets, and the age of your system and equipment. If you have pets in the house, you should consider changing the filter every 60 days or 2 months, and for households with multiple pets or people with allergies or respiratory conditions, we recommend changing the filter every 20-45 days.
Vacation homes or vacant homes that don't have much use can expect to change filters every 9-12 months. The more you use your home, the more often you need to change the air filter. For 1 to 3 basic air filters, brands usually advise changing them every 30 to 90 days. If someone in your family suffers from mild to moderate allergies, you can put on a better air filter or change it more frequently. The only way to determine how often you need to change your air filter is to perform a visual inspection of the filter each month. After a few months, you'll get an idea of how quickly it gets dirty.
You will need to re-evaluate if you have a new pet or if the outdoor air quality has been poor. The ideal is to change your air filter every three months, however, there are certain factors to consider when determining when to replace an old filter. It's a general recommendation to change your home's air filter every 30 days when using less expensive fiberglass filters.By removing the air filter from the air handler, if you hold it close to a light source, you can see if the filter is dirty or clogged; if you can't see the light through the filter, it's definitely time to change it. The longer the filter is in place, the more dirt, dust and allergens will be trapped, clogging the filter and decreasing its efficiency. The only type of filters that trap allergens and spores are HEPA, or high-energy particulate air filters.
Typical recommendations range from every 30 days for cheaper fiberglass filters (which often don't do a good job of filtering), to 6 months for high-end pleated filters. In general, filters with a MERV 16 rating or lower are considered HVAC system grade filters for residential, commercial, and general hospital use. Filters with higher MERV ratings trap small particles more effectively than filters with lower MERV ratings. However, if replacing the air filter simply isn't possible for an extended period, going beyond 90 days won't cause irreparable damage to your air conditioning system. Air filters typically have a MERV (Minimum Efficiency Report Value) that determines the type and size of contaminants against which the filter will operate. However, the smaller the appliance used for cooling, the small space usually comes with smaller filters, so you may need to change the filter as often as a filter in a larger home. More cycles mean more passes through the filter and opportunities to trap contaminants, so filters typically fill faster during periods of heavy use.
Generally, households with one pet should replace filters after two months; those with more than one pet may need to replace the filter once a month.
