How to clean & maintain a MRCOOL mini split AC

When was the last time you gave your MRCOOL mini split air conditioning unit some TLC? Keeping your unit clean improves air quality and the efficiency and lifespan of your system.

Like all air conditioning systems, MRCOOL units require periodic maintenance that includes easy do-it-yourself tasks and checks by an HVAC professional.

Let’s unpack everything you need to clean & maintain your ductless MRCOOL AC so you can keep it running smoothly for years to come.

Disclaimer: The information provided in this article may not apply to your specific appliance model. While we strive to offer helpful advice for all types of appliances, variations in models and configurations can lead to differences in cleaning recommendations. For the most accurate guidance, we strongly recommend consulting the use and care manual for your specific appliance model.

Why it’s important to clean & maintain your mini split AC

Dirty filters and coils can strain performance and allow mold, bacteria and dust to circulate through your home. But luckily these compact ductless systems are easy to clean yourself, aside from the annual maintenance visit from your local HVAC technician.

By regularly cleaning and maintaining your mini split AC, you can:

• Prevent frequent and expensive emergency repairs
• Maximize the unit’s cooling efficiency
• Extend the unit’s overall lifespan
• Improve your indoor air quality

What you need

• Soft cloths
• Mild detergent
• Vacuum with a brush attachment
• Garden hose
• Drain line brush kit
• Fin comb for air conditioner coils
• Screwdriver (for removing panels to access filters)

• Bucket of warm water for washing dirty filters
• Gloves

Safety precautions

To clean your MRCOOL mini split AC…

• Turn off the mini split system and disconnect it from the power supply.
• Never spray water into the outdoor unit’s interior or on indoor unit components.
• Be very careful to avoid damaging the thin copper coils.
• Use a fin comb specifically made for AC units when straightening bent coils. Using the wrong tools may tear the metal.
• If the appliance has recently been used, give it plenty of time to cool down before working on it.
• Take your time while working to prevent accidents and personal injuries. Rushing is the enemy of precision.
• Be gentle when handling or removing parts. Excessive force might damage the appliance or cause personal injury.

How to clean a MRCOOL mini split AC

Clean or replace the air filter(s)

The indoor unit air filter(s) stops dust, pet allergens and allergens from clogging up your ductless system. As the filter(s) become loaded with debris over time, airflow gets restricted.

The air filter should be cleaned every 2-4 weeks and replaced at least once a year. Some units have multiple filters, so make sure you’re keeping up with all of them if you have one of these models.

To remove the filter(s):

1. Make sure the unit is turned off.
2. Unscrew and remove the front panel covering the filter. Some models have clips instead of screws that you’ll need to remove.
3. Slide out the filter by gently pulling it towards yourself.

Check the filter(s) to determine what to do next:

• If the filter is slightly dirty, vacuum with a brush attachment.
• If the filter is heavily clogged, wash it gently with mild detergent and warm water. Rinse and dry it thoroughly before reinstalling it into the unit.
• If the filter is damaged, throw it away and install a new air filter of the same size that’s compatible with your specific model.

After cleaning the air filter(s), allow them to completely dry before sliding them back into position and replacing the front panel. Wet filters can damage your unit and breed mold!

Clean the indoor unit housing & vents

While the filters catch most dust and dirt, the indoor unit housings still require regular cleaning.

Only wipe down the housing and vents with soft, damp cloths. Pay special attention to the air intake vents, supply vents (where air flows out) and any accessible louvers or vanes that direct airflow.

Avoid liquid cleaner sprays, which may leak inside the sensitive system!

Clean the outdoor condenser coils

The outdoor condenser coils on mini split wall units consist of thin metal fins and tubes containing pressurized refrigerant. As the refrigerant cycles between gas and liquid states, it absorbs and releases heat to facilitate cooling. Dirty coils or coils blocked with debris (like leaves, grass clippings, dust, etc.) can’t transfer heat efficiently, so they may strain your AC system and shorten its lifespan.

To clean the condenser coils:

1. Unplug the unit.
2. Remove the outer casing panels to access the coils. You’ll probably have to unscrew a few bolts or clips.
3. Check that the coil fins are straight. Carefully bend back any fins that have buckled while handling. Make sure to use a fin comb tool to avoid further damage.
4. Use a hose to spray off any debris and dirt that is stuck to the coils. Start from the top and spray down. For severe grime, use a commercial-grade condenser cleaner.
5. If needed, straighten any bent fins again when you’re done spraying the water.
6. Check that there isn’t any debris blocking the airflow.

Tip: Schedule professional coil cleaning if your unit loses cooling capacity or ice builds up on coils while you’re using it.

How to maintain your condenser coils in between cleanings:

• Inspect the external condenser unit surfaces in between appointments.
• Clear away any leaves or debris around the base.
• Straighten any bent fins on coils damaged by wind or yard equipment.

Clean the condensate pan & drain line

Air moisture collected by the evaporator coil drains into a pan below, then exits outdoors via a small condensate drain line. Clogged drains can overflow the pan and leak water, which can cause indoor water damage and mold growth.

It’s recommended to clean the condensate pan and drain line at least once a year.

To clean the pan and drain line:

1. Make sure the unit is turned off.
2. Remove the condensate pan and clean it with mild detergent.
3. Use an AC drain line brush kit to flush the drain line from both ends.
4. Make sure the drain line slope allows water to exit outdoors. Adjust it if needed.
5. Pour a cup of water into the drain pan to check for leaks before you reinstall it.

How to maintain your condensate pan and drain line:

• Check for clogs in the drain line every 2-3 months by shining a flashlight into the ends
• Use pipe cleaners to clear minor clogs
• Flush the line with drain cleaner, compressed air or water
• Treat stagnant lines with algae tablets
• Pour distilled white vinegar through the line every few months to prevent buildup

Inspect the refrigerant lines

You should check the refrigerant lines that connect the indoor and outdoor units at least once a year for leaks and damage.

If you have leaks, these would show up as oil stains at connections & brazed joints. Leaks require professional HVAC repair to add refrigerant sealant.

If you find any damage, call a licensed HVAC technician. Lines should never kink or dent when handling the unit. Correct refrigerant level and unobstructed tubing are necessary for heat transfer.

Get your unit professionally serviced annually

While you can clean filters, housings and coils yourself, you should always get your MRCOOL mini split AC professionally serviced once a year since technicians can find issues that won’t be apparent to most users. Refrigerant leaks, for example, can slowly degrade your mini split’s performance over months or years. The only way to detect the gradual loss of refrigerant is through specialized equipment.

HVAC technicians also use manifold gauges to measure system refrigerant pressures and compare them to target levels for particular AC units. If the charge is low, they can perform additional leak testing.

Professional maintenance checks for the following issues that you can’t spot or work on yourself:

• Refrigerant levels & leaks
• Carbon monoxide issues
• Electrical board, wiring and connection issues
• Compressor, fan and blower function
• Deep coil cleaning
• Deep drain pan & line clearing with high-pressure air or nitrogen
• Combing hairline coil cracks
• Thermostat control & system responses

It’s best to contact your HVAC company each spring to schedule maintenance before the cooling season ramps up. A maintenance visit may cost around $100-150, but it can help you save on emergency repairs down the road. Well-maintained units can last over 15 years!

Mini split vs. ducted central AC maintenance

MRCOOL mini split units differ significantly from ducted central air conditioners in terms of complexity and maintenance needs. Central systems incorporate extensive ductwork, air supply registers, return grilles and elaborate control boards and have multiple points where air could leak.

While central air conditioners offer a cooling solution for a whole home, they’re more expensive and include more parts that can fail over time.

Here’s a general breakdown of what you can expect during maintenance on a MRCOOL mini split AC vs. a ducted central AC system:

Maintenance task	MRCOOL mini split	Ducted central AC
Professional annual inspections	Recommended	Strongly recommended
Refrigerant level checks	Annual	Annual
Refrigerant line leak checks	Annual	Annual
Condenser cleaning	Annual (DIY or professional)	Annual (professional)
Air filter replacement	DIY, every 2-4 weeks	DIY, every 1-3 months
Drain line cleaning	DIY, every 2-3 months	Professional with heating/cooling season startups
Duct cleaning	Not applicable	Professional, every 3-5 years
Duct sealing	Not applicable	Professional (to test for and seal leaks)

Additional information

Thanks for stopping by! We hope this guide helped you learn how to keep your MRCOOL mini split air conditioner clean and maintained.

If you run into any issues, just give us a call at 1-877-477-7278 or start a chat with a pro on our website so we can help you through it. We’ve got many more troubleshooting and repair guides on our DIY blog and YouTube channel and all the parts you need to do it yourself at AppliancePartsPros.com. 

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