How to Clean a MRCOOL DIY Mini Split: Filters, Coil and Outdoor Unit

DIY mini split cleaning is mostly ten-minute jobs, and the ones that take longer only come up once or twice a year. Here is how to clean a MRCOOL DIY Select, EasyPro or 5th Gen wall unit, what to do on a ceiling cassette, and where the job stops being a DIY job.

What parts of a mini split need cleaning, and how often?

Why does cleaning matter so much on a mini split?

A mini split has no big return duct and no thick filter in a hallway. The thin mesh filter right behind the front panel is the only thing between room dust and the coil. Let it clog and airflow drops, the unit runs longer to hold your setpoint, and in cool mode the coil can get cold enough to ice over.

It is also on you under the warranty. MRCOOL's warranty documents list filter cleaning as normal owner maintenance that the warranty doesn't cover, and they exclude damage from improper operation.

How do I clean the filters?

1. Turn the unit off with the remote, then switch it off at the breaker.
2. Lift the front panel. On most wall units it swings up from the bottom edge, and your owner's manual shows the exact release for your model.
3. Slide the filters down and out. Note which side faces the room.
4. Vacuum the dusty side with a soft brush attachment.
5. Rinse with lukewarm tap water, spraying from the clean side so dust pushes back out the way it came in. Add a drop of dish soap if the filter is greasy from cooking.
6. Let the filters air dry fully in the shade. Never put them back wet, and don't use a hair dryer on them.
7. Slide them back in, close the panel and restore power.

Wipe the louvers and the outlet with a damp cloth while the filters dry. Gray fuzz on the louvers is a sign the filters went too long.

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How do I clean the indoor coil?

With the filters out you can see the coil: rows of thin aluminum fins across the top and front of the unit. A light gray film is normal. Here is a once or twice a year cleaning:

1. Power off at the breaker and take the filters out.
2. Lay a towel over the wall and floor below the unit.
3. Keep spray away from the display and the electronics on the side of the unit. Follow the cleaner's label and your owner's manual.
4. Spray a no-rinse foaming coil cleaner made for mini splits straight into the fins, not across them. The foam drips into the drain pan and out the drain line.
5. Wait the time on the label, put the filters back and turn the system on in cool mode so condensate flushes the rest away.
6. Go outside and check that water is running out the end of the drain line.

MRCOOL sells its own cleaning kit, and the MRCOOL Care program for EasyPro and 5th Gen owners ships a kit every year.

How do I clean the outdoor unit?

1. Switch off the outdoor unit at its disconnect switch and at the breaker.
2. Pull leaves, grass clippings, cottonwood fluff and spider webs off the coil and out of the base by hand.
3. Spray the coil fins with a garden hose on a gentle setting, straight on. A pressure washer will fold the fins flat in seconds.
4. Trim shrubs back and move anything stored nearby. The installation manual for your size lists the clearances.
5. Let it dry for half an hour, then restore power.

In winter, brush snow off the top and keep the base clear so defrost water can drain away. Don't chip ice off the coil with a tool. If the unit sits low and snow keeps burying it, an equipment pad or a wall bracket raises it, and both are in our accessories collection.

When should I call a pro cleaning service?

Behind the louvers sits the blower wheel, a long drum of small curved blades. In humid climates it can collect black growth that a coil spray never reaches. Cleaning it right usually means taking the unit's cover and parts off and using a wash bag and a pump sprayer. That work is what local HVAC companies and mini split cleaning services charge for.

• A musty smell comes back within days of a filter cleaning.
• You see black spots on the louvers or the blower wheel with a flashlight.
• The coil is matted with dust or pet hair, not just a light film.
• You don't want to stand on a ladder with a spray bottle above your head.

Water dripping from the indoor unit or ice on the coil is a different issue. Turn the system off and contact MRCOOL support at support.mrcool.com. Our phone line is for sizing and choosing systems, so we can't troubleshoot a unit by phone.

What if my setup is different?

What if I have a ceiling cassette?

The filter sits behind the grille in the ceiling. Use a sturdy stepladder and a second person to take the grille. Coil cleaning on a cassette is awkward overhead work, so many owners do the filters and leave the coil to a pro.

What if the unit is in a kitchen?

Cooking grease makes dust stick. Wash filters every two weeks with a little dish soap and expect the coil to need cleaning twice a year.

What if I have dogs or cats?

Pet hair mats on the filter fast. Vacuum the filters weekly in shedding season and wash them every two weeks.

What if I'd rather not climb a ladder at all?

That's a fair call at any age. Book a pro cleaning once a year and ask them to show you the filter release, so the monthly part becomes a two-minute job from a step stool.

What should I do next?

Put a monthly reminder on your phone for the filters and a spring and fall reminder for the outdoor unit. Keep your owner's manual handy; ours are on the manuals page. If the cleaning is done and the room still won't hold temperature, work through our not-cooling checklist before you contact MRCOOL.