Short answer: Most mini split filters are reusable. You clean them, not replace them, on a schedule set by your manual. Replace a filter when it is torn, warped, will not come clean, or your manual says it is due. Buy the filter made for your exact model, and make sure it sits snugly without bending.
Clean or replace?
Start with the filter in your hands.
| What you see | What to do |
|---|---|
| Light dust or a gray film | Clean it and reuse it |
| Sticky or greasy buildup | Wash it, then check that it comes clean |
| Torn mesh, cracks or warping | Replace it |
| Still dirty or smelly after washing | Replace it |
| Your manual gives a replacement interval for this filter | Follow the manual |
Lennox says that if a filter is extremely dirty or overdue for replacement, you should install a new one as soon as possible, and that neglecting the maker's recommended filter replacement can cause poor cooling and heating, water build-up and leakage, mold and mildew growth, bad odors and system damage.
Cleaning steps are in how to clean a mini split.
How to find the right replacement
Take your time here. A wrong filter wastes money, so do these in order.
Do not guess. Filters differ by brand, model and indoor unit style.
- Find the model number. It is usually on a label on the indoor unit and in the owner's manual.
- Look up the filter in the manual or the maker's parts page. The manual shows the filter type and how it comes out.
- Buy the part listed for your model. If the maker sells it, that is the safest choice.
- Check the fit. The EPA says a filter should fit snugly so air does not leak around it, and that you should not have to bend or crush it to make it fit.
Some units also have a small extra filter clipped to the main one. Check your manual so you replace the right part.
Do mini split filters clean the air?
Not much. The EPA says the filters typically installed in mini-splits are meant to keep large particles like pet hair and lint from clogging the equipment, and they do not filter fine particles. Some products claim better filtering. The EPA says to check that a filter is rated MERV 13 or higher before trusting that claim, and that a portable air cleaner is an option if your unit does not have one.
So a mini split filter is there to protect the unit. If you want cleaner air, that is a separate purchase.
How often two makers say to clean it
Cleaning is the normal job, and the makers give different timing, so go by your own manual. Carrier's owner manual says to take the filters out and clean them once a month. Midea's owner manual says to clean the filter once every two weeks. Both say to clean more often in a dusty home, and both say a clogged filter cuts cooling.
Both manuals give the same washing advice. Wash a mesh filter in warm water with a mild soap, rinse it, shake the water off and let it dry in a cool, dry place. Carrier adds that sunlight can shrink the filter while it dries, so keep it out of direct sun. If a small air-freshening filter is clipped to the big one, unclip it and vacuum it instead of washing it.
Some Midea models can remind you. Midea says CL can flash after 240 hours as a cleaning reminder, and nF can show after 2,880 hours as a replacement reminder, on models that have the feature. Carrier says to replace a filter that is torn or badly worn, and to order the part through your dealer.
When the filter is not the problem
A new filter will not fix everything. If you still have a problem after cleaning or replacing the filter, see:
Safety
Turn the unit off before you remove a filter. Midea's owner's manual also tells you to disconnect power first and to avoid touching the metal parts inside, because the edges are sharp. Let a washed filter dry fully before it goes back in.
Related reading
- If a Samsung unit shows CF, read the Samsung CF code guide.
Sources
- Lennox: What to do if your mini split is not cooling
- EPA: Do ductless mini-split heat pumps filter fine particles out of indoor air?
- Midea ductless split owner's manual
Follow your unit's own manual. This is general information.
