How to Clean Mini Split Filters
How to clean mini split filters is the one maintenance job every owner should learn, because a clogged filter is often the reason you end up with weak airflow, musty smells and frozen coils. The good news is it takes about ten minutes and you don't need any tools.
How often to clean them
Most manufacturers say to clean the filters every two weeks when the system is running a lot. If you have pets, a dusty shop or someone in the house who smokes, check them every week. When the weather is mild and the unit is barely running, once a month is usually enough. The filters are plastic mesh and are meant to be washed and used again, so there is nothing to buy.
What you need
- A soft brush, or a vacuum that has a brush attachment
- Lukewarm water and a little bit of mild dish soap
- A towel
Step by step
- With the remote, you can turn the unit off, then switch off the breaker or unplug it. You don't want the fan starting while your hands are inside.
- Lift the front panel. On most wall heads it hinges up from the bottom edge and can stay open on its own or with a small prop.
- Pull the filters out. They usually slide up and out, or pop off from tabs at the bottom. Note which way they came out.
- You can vacuum or brush off the loose dust first, from the side that faced the room.
- Rinse them under lukewarm water. If there's grease or grime, put a drop of dish soap on them and scrub them with a soft brush. Don't use hot water, it can warp the plastic frame.
- Let them air dry completely in the shade. Putting a wet filter back in can cause mold to grow, and leaving it in direct sun or using a hair dryer can bend the mesh.
- You can slide the filters back in the same way, close the panel and turn the power back on.
Signs a filter needs attention
If the airflow feels weak compared to how it used to be, the room takes longer to cool or heat, or you smell something off when the unit comes on, check the filters first. A filter that is very clogged can also cause the indoor coil to ice up in cooling mode, and some units will show a filter reminder light after a set number of run hours. On many remotes you can reset that light by holding the filter or reset button after you've cleaned it.
When washing isn't enough
Clean filters only protect the coil. Behind the filter, if the fins look gray and stuck together, or if the blower wheel has black spots on it, that needs a coil cleaning, which is a bigger job. Some owners do it with a spray-on no-rinse coil cleaner and a bag kit, and others hire it out every year or two. If you ever see a flashing code on the display after cleaning, look it up in our mini split error code lookup before you call anyone.