Cleaning the filters on a ductless mini-split

A ductless mini-split heats and cools through one or more indoor units, or heads, on the wall or ceiling, each with its own fan, coil and filter. The standard filters are washable mesh. They catch little of the fine dust, but they let air through easily, which the small, low-power fans in the heads need. To keep that airflow up, the mesh filters typically need cleaning about every two weeks. Many manufacturers give that schedule, and your manual has the exact one.

What you need

• The system's manual
• A vacuum with a brush attachment
• A sink or tub, for washing
• A towel

Steps

1. 1

   Turn the head off

   Turn the indoor head off with its remote before you open it.

   1 min

2. 2

   Open the front panel

   Lift or unclip the front panel the way the manual shows, and slide out the mesh filters.

   2 min

3. 3

   Vacuum or wash the filters

   Vacuum the dust off, or wash the filters with water. Dry them with the towel and let them finish drying before they go back in.

   5 min

4. 4

   Look at the blower wheel

   With the filters out, look closely at the blower wheel and the air vanes. A buildup of dust and mold there means the head is due for a deep cleaning.

   2 min

5. 5

   Put the filters back

   Slide the filters back in, close the panel, and turn the head back on.

   3 min

6. 6

   Do the extra filters too

   If the head has extra filters for better air quality, clean or replace them on their own schedule.

   2 min

Deep cleaning

Wall-hung heads also need a deep cleaning every 1 to 3 years. Humid weather and heavy use mean more often, and a head in a dry climate or used only part-time can go longer. Deep cleaning generally isn't a DIY job. The heads are hard to take apart, and the work takes a pressurized sprayer, special cleaners and a bib around the unit to catch the runoff. An aerosol can of foaming coil cleaner isn't a substitute. A professional sprays out the mold between the coil fins and scrubs the air path, the vanes and the drain tray.

The outdoor unit

Keep snow from piling up around the outdoor unit. Water that drips onto it and freezes, such as meltwater from a deck or a roof edge above, sharply cuts how much heat it can deliver. If ice keeps building up on it from above, a cover over the unit can protect it.

Heat pumps for people who grew up with a furnace explains how the system heats and cools.