What changes the schedule
The right interval depends on the filter type, the size of the household and what is in the air. Homes with pets, smokers or ongoing dust from construction need changes more often. Thin one-inch filters fill faster than deep media filters.
How to check a filter
- Turn the system off at the thermostat.
- Slide the filter out and note the airflow arrow on its frame.
- Hold it up to a light. If you cannot see light through it, replace it.
- Slide the new filter in with the arrow pointing toward the blower.
- Write the date on the frame so the next check is easy.
When the filter is not the problem
If airflow is weak with a clean filter, or the system short-cycles, ice forms on the indoor coil, or rooms heat and cool unevenly, the cause is elsewhere. A technician can check the blower, coil, ducts and refrigerant charge.