The short answer
Check the filter every month and replace it when it looks dirty. For many Las Vegas homes that means every 1 to 3 months. Homes with pets, recent construction nearby, or frequent dust storms may need it monthly in summer.
Why it matters so much here
- Your AC runs many more hours a year than in milder climates, so it moves more air through the filter
- Desert dust loads filters quickly
- A clogged filter restricts airflow, which can freeze the indoor coil, overwork the blower and raise your electric bill
Picking the right filter
Use the exact size printed on the old filter's frame. For most homes, a mid-range pleated filter balances filtration and airflow. Very high-efficiency filters can restrict airflow on systems that weren't designed for them.
Signs your filter is overdue
- It looks gray or you can't see light through it
- Weaker airflow from the vents
- More dust on furniture than usual
- Ice on the refrigerant lines
Don't forget mini-splits
Ductless mini-split heads have washable filters. Rinse them whenever they look dusty.
A regular AC tune-up includes a filter check, and we can tell you the right size for your system.
Filter details people often miss
Filters at the air handler versus the return grille
Some homes have a filter in a ceiling or wall return, others in a slot at the furnace or air handler, and a few have both. If both are installed, you're doubling the restriction for no extra benefit. Pick one location. Check the airflow arrow printed on the frame and point it toward the equipment, away from the room.
MERV ratings in plain terms
MERV is a scale for how fine a particle a filter catches. Very low ratings catch only large dust and lint. Mid-range ratings trap finer dust and pollen without choking airflow on most residential systems. The highest ratings belong on systems designed for them, or you risk weak airflow and a frozen coil, especially on older equipment.
Monsoon dust storms and filter checks
When a dust storm rolls through in summer, check the filter afterward even if it's only a few weeks old. Fine dust can load a filter in a single day if windows were open or the house is leaky. The same dust settles in ducts over time; see duct cleaning if it keeps blowing from vents.
Keeping a stock of the right size
Buying filters in a multi-pack means you'll actually change them instead of putting it off for a trip to the store. Write the size on the return grille or the inside of the closet door. If you're unsure of the size or type, we can confirm it at your next tune-up.
Common questions
Where is my AC filter?
Usually in a return air grille on a wall or ceiling, or in a slot at the furnace or air handler.
Can a dirty filter stop my AC from cooling?
Yes. Restricted airflow can freeze the coil, and the system stops cooling until it thaws.