A new air filter should be white or off-white in color. If it's gray and dirty, it's time to change it. The most obvious sign that you need a new air filter is black smoke and soot coming out of the exhaust pipe, or a smell of gasoline when the engine starts. To detect a filter that needs to be changed, take a look at it.
A clean, fresh filter will be mostly white in color, but will darken as dust and dirt build up. If the filter looks very dark and dirty, it's time to change it. You can also ask a technician to check your filters for you. A good indicator of old and dirty air filters can be found by comparing the surfaces immediately next to the vent with other surface areas.
If that section of the carpet appears to be visibly dusty or covered by an ash-like substance, then it's time to change the air filter. The only way to ensure how often you need to change your air filter is to perform a visual inspection of the filter every month. After a few months, you'll get an idea of how quickly it gets dirty. You may need to re-evaluate if you have a new pet or if the outdoor air quality has been poor.
Another symptom that your engine has air problems can be found when you step on the accelerator pedal. If the car moves forward and doesn't move as smoothly as you normally recognize, check the air filter further for dirt buildup. A clear sign that the AC filter needs to be replaced is when the back of the unit is too hot. If the filter is heavily soiled, you may feel warm air coming out the back of the unit.
A clogged filter forces the air conditioner to work harder to keep the house cool, leading to more frequent air conditioning repairs and ultimately shortening the life of the unit. To reduce this load, simply change the AC filter regularly. In general, most air filter manufacturers and HVAC companies recommend changing your air filter every 90 days or 3 months. That may change 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. Usually, vacation homes or vacant homes that don't have much use can expect to change filters every 9-12 months. The general consensus is that the more you use your home, the more you need to change the air filter. Fiberglass air filters are more affordable but less efficient at capturing dust and particles in the air.
The HVAC air filter helps keep indoor air clean by trapping mold particles, pollen, and other contaminants moving through the system. If you change the filter and the unit still doesn't cool down, call a technician to examine it. If you notice that your air conditioner doesn't cool down as it normally does or blows hot air, check if your air filter is clogged first. If it is clogged, it can start to create pressure inside your HVAC system, which can force outside allergens into your home.
Outdoor air quality can have a big impact on how often the air filter becomes dirty and needs to be replaced. You will no longer be able to filter the air properly, allowing dust and contaminants to enter your HVAC system. In smaller homes, where there is less use of HVAC systems, there will be fewer changes needed for filters than in larger family homes with numerous occupants. Over time, filters can become dirty and clogged which can have negative effects on engine performance so it's important to change them regularly.
If you notice spitting or clicking when your engine is idling, you may need to change your filter right away.
