Home central air conditioning systems usually share their filtration with the main furnace, so the same rules apply for changing the filter. Fibreglass based filters (the most common) should be replaced every couple of months and paper based filters every four to six months. Electrostatically charged filters can be cleaned and reused when dirty.
While regularly scheduled filter changing intervals are recommended, it’s best to inspect your HVAC system and learn when your filter needs to be replaced. As building environments and locations are all different, you may find you need to change your filters more often in summer than in winter due to an increase in dust and pollen in the air and if you tend to keep your windows open to enjoy the summer breeze (when you’re enjoying mothers nature’s air conditioning). If you own pets or have a lot of carpeting in your home you may also need to change your filters more frequently.
Clean Those Coils!
The A-Coil in the AC plenum should be cleaned every 3-5 years. A visual inspection will confirm whether it is dirty and requires a cleaning. Why clean them? Dirt build up on the coils is hard on your air conditioning system, requiring it to work harder to maintain the temperature in your home. This can place undue stress on the system, resulting in premature wear and tear and possible failure. It also makes the system less efficient, which increases the cost of operation. As the A-Coil is fragile and can be damaged easily, it is recommended that you don’t undertake the cleaning yourself. This regular maintenance can pay for itself through continued, trouble-free efficient operation of your central air conditioning unit.