Ductless systems didn’t gain popularity in North America until relatively recently. However, it’s no surprise that they’re becoming quite common. They are quiet, efficient, and well worth the price in the long run.

Highwall ductless systems have their downsides, though. When they get dirty, they can spread gunk beneath them and make a room smell quite nasty. To help you solve those problems for your customers, we’ve put together a guide for cleaning the Mitsubishi Highwall Mini-Split in two different ways.

Disclaimer: Some of these steps are fairly universal, and others are specific to certain models of Mitsubishi high-wall units. Follow the manufacturer's instructions ABOVE ALL.

Method #1

The first method is going to be disassembly of the unit and removal of the blower wheel. You wash the blower wheel outside with a hose (and sometimes with cleaner), let it dry out, and put the unit back together.

1. Locate the unit power source and turn it OFF

As with any job that requires you to handle parts that normally move, you will want to make sure the unit is powered off before you begin taking it apart to clean it.

You’ll remove the blower wheel later, and you could end up with some messy results if it starts spinning while you’re trying to take it out. Be safe, exercise common sense, and don’t take risks. Just turn the unit off and confirm with a meter.

2. Remove the air filters

You’ll take apart the air handler in stages. The first thing you’ll do is pull out the air filters on both sides of the air handler.

3. Remove the horizontal vanes

The next step is to remove the horizontal vanes from the bottom of the mini-split.

The horizontal vanes each have three tabs right on the inside. You can slide the tabs a little bit to the right, and the vanes should pop right off once you slide all three tabs. The Mitsubishi Mini-Split has two of these vanes, but other manufacturers may have a different number. You can still often remove them the same way.

4. Expose and remove the three Phillips-head screws on the bottom

Right below the place where you removed the vanes, there will be three tabs along the bottom of the unit. You can pull these tabs up to expose the screws underneath them.

These screws are somewhat large and require an appropriately-sized Phillips-head screwdriver for removal, so make sure you have one on hand.

5. Remove the unit cover

Once you have removed the screws, slide the bottom of the face out and gently pull up and back.

There will likely be some clips or tabs on top of the air handler. The Mitsubishi Mini-Split has some clips along the top. If your unit has these, you will need to release them as you remove the face. These may vary by manufacturer and model, so be mindful of what’s on top of your unit and what you need to do to remove the unit’s face.

The unit’s face should pop off quite easily if you’ve removed everything that needs to be removed and pressed everything that needs to be pressed.

6. Release the drain pan

Most of the time, the drain pan should be relatively easy to remove. There may be a tab beneath the drain pan, so you’ll push that in. Move the drain pan assembly by pulling it towards you and lowering it gently. That way, you allow it to rest downward from the unit.

There may be water in the drain pan. If there is water, make sure it’s all dry before you release the pan. It’s also a good idea to make sure you have some drop towels around the area and suck the debris out of the drain pan with a wet/dry vacuum. You wouldn’t want to damage any of the customers’ property.

You may not be able to release the pan on all models. If you cannot release the drain pan, we recommend using the Mini-Split Bib® Kit to clean the mini-split in place and without further disassembly.

7. Loosen the set screw in the blower wheel

There is a Phillips-head screw set inside the blower wheel. It should be near one of the side edges of the wheel. Locate it.

Loosen the screw either completely or nearly all the way using a Phillips-head screwdriver. Otherwise, the blower wheel won’t release itself.

Be careful with this step. The fins on the blower wheel are a bit fragile and may crack or scratch easily. When using metal objects near the blower wheel, mind the sharp edges to avoid damaging the fins.

8. Move the coil to expose and remove the blower wheel

You have to loosen the coil before you can move it. A few screws connect the coil to the unit, typically on the opposite side of the blower wheel’s set screw. (In our pictures, the set screw was towards the right side of the unit. The screws that connect the coil to the unit were on the left side, just above the man’s hand in the picture.) Remove the screws with a Phillips-head screwdriver.

After removing the screws, you can move the coil by gently pulling it up and towards you. This part can be quite tricky for techs, especially on the first try. Hold the coil in place a bit above the unit. The blower wheel should be in plain view. Remove the blower wheel and return the coil to its original position.

9. Clean the blower wheel outside

Most of the time, a simple garden hose will suffice for cleaning the blower wheel.

When you need to use a proper cleaner, we recommend Refrigeration Technologies Viper cleaning products. We like the Viper EVAP+ evaporator coil cleaner because it’s quite strong and deodorizes the blower wheel nicely.

Be mindful of where you clean the blower wheel. You don’t want to wash the grime all over a customer’s freshly pressure-washed driveway or near their prized flower garden. Wash the blower wheel in a place where the debris won’t be an eyesore.

Let the wheel completely dry before you attempt to reassemble anything.

10. Clean the evaporator in place

This step is still best done with the coil bib in place, as shown in Method #2 further down. If you don't use the bib, you will be left using a combination of a rag, some spray cleaner (such as Viper in the spray can), and possibly a shop vac and soft bristle brush. It can be a tedious process, and a lot of water management is required to keep from making a mess.

11. Reassemble the unit

Simply put, you will want to do everything you just did backward. We’ll go through the reassembly steps, but we’ll keep it brief.

Once the blower wheel has dried completely, reinstall it by lifting the coil and setting it in its usual place. Set the coil back down and re-screw it into place.

Tighten the set screw on the blower wheel so that it fixes to the motor shaft.

Raise the drain pan back up to its usual position and secure it in place.

Put the unit’s face back on. Once it’s back on, re-screw the three Phillips-head screws at the unit’s bottom and place the protective tabs back over them.

Add the horizontal vanes back, and finish the reassembly by re-adding the air filters.

Restore power and clean up the job site.

Method #2

The second method allows you to stay in one place by collecting the water indoors using a Mini-Split Bib® Kit to collect the water and cleaner without making a mess. Even if you decide to take the blower wheel out and rinse it outside, we recommend using the Mini-Split Bib to clean the coil and internal shroud if those need cleaning. With this method, you can clean the blower wheel in place; it still just takes some time and care to get it completely clean.

1. Turn the power OFF and disassemble as necessary

As with any job, turn the unit’s power off.

The Mini-Split Bib makes total disassembly unnecessary, but you may decide to take certain parts of the unit off and clean them separately. (For example, you might prefer to wash the face separately if it looks exceptionally filthy.) We explain all the disassembly steps in Method #1, so refer to that for the procedure for guidance.

Even though the bib goes around the entire air handler, it’s a good idea to remove the air filters.

2. Fasten the Mini-Split Bib around the remaining parts of the air handler.

The Mini-Split Bib® comes with brackets that hook to the upper corners of the unit. They fasten the bib to the mini-split.

The bib comes with a splash guard to apply between the backside of the bib and the wall. For added coverage, you can cover parts of the wall in adhesive tape to protect against spills and water damage to the wall.

The brackets have some ropes attached to them. The ropes cross over the bib’s front, and you can tighten them to fit the bib snugly around the air handler.

The bib comes with a funnel at the bottom for the water and cleaner to run out. Place the funnel in a bucket.

For a video tutorial on fastening the Mini-Split Bib®, we recommend watching this Mini-Split Bib tutorial on SpeedClean’s official YouTube channel.

3. Spray the unit to clean it

We recommend using a SpeedClean CoilJet to clean the unit. (Be sure to use the recommended SpeedClean cleaner if you use their CoilJet.) This cleaning apparatus has adjustable wands to help you reach difficult crevices. It also provides an easy means of mixing water and chemicals into a cleaning solution.

The first blast of water will have the highest pressure, so we suggest spraying your first bit of water into the bib. This will prevent the high-pressure liquid from splashing back at you when you aim it at the unit.

Once you’ve got a steady flow of cleaning solution, you can clean all inside the unit. The soapy solution will run down the inside of the bib and into the bucket.

You can use various wands to get into hard-to-reach places, like the backside of the coil. You can use the flex wand to reach the back from the top of the unit.

Let the unit dry before proceeding.

4. Reassemble the unit

Once everything has dried, you can replace the parts you removed from the unit. If you cleaned the unit with the blower wheel inside, keep the bib ON after putting everything back together.

When you’re ready, turn the power back on. The blower wheel may release some water and cause some splashing. That’s normal, and that’s why you want to make sure the bib is still on.

When the blower wheel doesn’t appear to be spraying any more water, you can remove the bib and clean up your work area.

As a best practice for any cleaning job, make sure you have plenty of drop towels and maintain a clean workspace. Whether you clean indoors or outdoors, there are plenty of ways to make a mess with a mini-split cleaning job. The last thing you want to do is damage someone’s expensive hardwood flooring beneath their unit.