New filter (left); used filter after 2 months of summer (right)
The most important maintenance task for the efficiency of your air conditioner is to clean or change its filter, according to the U. S. Department of Energy (DOE).
Filters should be changed or cleaned at least every three months, but during periods of high use, such as in summer, they may require changing each month. High levels of dust or animal fur may also increase the need for a filter change.
A dirty filter reduces air flow and increases the amount energy needed to bring in each unit of air. The DOE estimates that changing your filter regularly will reduce the air conditioner’s energy use by 5 to 15 percent.