These units are small, and the blower wheel and evaporator coils can gunk up quickly. In many cases, mini-splits are visible in the living space, so odors and dirt are more of a problem than if the units were tucked away. So, we recommend routine cleaning and maintenance for ductless mini-splits to keep them odor-free and in tip-top shape.

This article will describe what a mini-split maintenance procedure looks like at Kalos. We follow the best practices included in the “Mini-Split Maintenance Best Practices” guide on SpeedClean’s website; Kalos president Bryan Orr wrote that initial guide.

WHY DO I NEED MAINTENANCE ON MY MINI-SPLIT?

On any type of A/C unit, regular maintenance helps prevent underperformance, poor indoor air quality, and premature failure. However, the little mini-split requires special attention during maintenance due to its size. It may be tempting to say, “If it ain’t broke, don’t fix it.” However, that’s an unwise approach to mini-split maintenance. When HVAC contractors don’t have a chance to perform maintenance, small issues can spiral out of control quickly.

Since ductless mini-splits are so small, they don’t hold a lot of refrigerant (also known as “Freon” or coolant). A small leak may not significantly affect a typical split system for a while. However, you’ll be much more likely to notice a performance drop with even small leaks if you have a mini-split system. During a maintenance procedure, we’ll check the charge of a mini-split and try to locate any leaks.

Mini-splits are also more likely to be in the living space. So, the sights and smells associated with dirty blower wheels are a much more significant comfort concern. In some cases, the blower wheel can even spit the dirt out of the unit and onto the surfaces below the unit. Not to mention, dirty blower wheels and filters reduce the air quality in your home.

With a good maintenance plan in place, you can expect better air quality, a more comfortable home, a more efficient HVAC system, and a longer-lasting unit.

WHAT TO EXPECT ON A MAINTENANCE CALL FOR A DUCTLESS MINI-SPLIT

So, it’s time to have your mini-split cleaned and maintained. You’re probably wondering what the technicians will do inside your house when you schedule this type of procedure. So, what can you expect on the day of service?

Preliminary conversations

Our techs should call you to let you know when they are on their way and when you can expect them to arrive. When our techs arrive at your home, they will put shoe covers on, greet you, and discuss the scope of the plan. The scope of the plan includes the maintenance procedures they’ll be doing and an approximate timetable of completion.

If you have noticed anything strange going on with your ductless mini-split, now is the time to let the technician know. The technician will inspect the system anyway, but they’ll be extra diligent if you bring any concerns to their attention.

If any payment is due at the time of the service, the technician will also let you know and ask you how you would like to pay.

Preparing for the cleaning

The technician will start by inspecting the entire system. They will run heat pumps in both heating and cooling modes to check for abnormalities in each operating mode. The technician will also check the coil’s cleanliness, listen for noises, examine the tightness of electrical connections, and assess the line set location and insulation.  If you notified the technician of any problems, they’ll pay close attention to the potential causes of those problems.

Before cleaning, the technician will need to shut off the power to the mini-split. They should let you know before shutting off the power and may give you an estimate of how long the house will be without A/C. Once they have confirmed that the system is off, they will lay drop cloths down to protect the floors and surfaces below the unit. In many cases, they’ll also connect a shop vacuum to the drain line to get standing water out of the drain.

Then, they will likely disassemble the unit. Some units may not need complete disassembly, but the filters will almost surely need to come out and be washed.

If needed, the technician will continue taking apart the unit by removing the vanes on the bottom. In some cases,  the technician will remove the face of the unit and likely wash it outside if they deem it necessary.

Sometimes, the blower wheel will also need to come out. When it does need to be cleaned outside, the technician will release the drain pan and let it hang down from the system. (We train our techs to make sure there’s no water in the drain that’ll splash on anything.) Then, the technician can lift the coil and access the blower wheel; they will loosen a set screw and remove the blower wheel from the unit.

The actual cleaning

Regardless of how much the unit has been disassembled, the technician will usually wash the filters outdoors with the hose and give them ample time to dry. If other parts have been pulled and need to be cleaned outdoors, the technician will do the same. Clean water will suffice for most cleanings, but we sometimes need to add non-toxic enzyme-based cleaners to exceptionally dirty blower wheels. The outdoor coil also needs cleaning and upkeep, so the technician will go outside and rinse the outdoor unit. If you have a regular maintenance schedule, then the outdoor unit shouldn’t get too dirty between maintenances.

Indoors, the technician will set up a bib, which is a large funnel-like bag that mounts to the unit and drains the water into a bucket below. Again, in many cases, the unit can be cleaned with just water. However, we may need to use non-toxic cleaners for exceptionally dirty systems.

The technician will give everything ample time to dry before reassembling the mini-split. They’ll also wait to make sure that the unit itself is dry before running the unit. There may still be a little bit of moisture on the blower wheel when the unit first starts up, so the technician will likely keep the drop cloth and bib in place to prevent splashing and property damage.

Cleaning and maintaining the drain or condensate pump

In many cases, the technician will clean the drain while reassembling the unit. If the shop vacuum is already attached, the technician can simply flush water through the drain. The technician can usually wipe the drain pan clean, but flushing water ensures that the drain line is clear.

Not all units will have condensate pumps. However, the ones that do will have a reservoir behind the indoor unit. The technician will pop off the top of the reservoir, clean it out, and disconnect the reservoir to clean the tubing. They will use a shop vac to clean out the tubing going to the drain pan like a normal drain line. They’ll make sure that there aren’t any patches of algae blocking screens, sensors, and other important parts.

In particularly stubborn drains or condensate pumps, the technician could potentially blow compressed air or nitrogen into the drain. However, flushing the drainage systems with water will often suffice.

Before the technician leaves, they will check to make sure that the unit is draining as it should. They’ll also make sure that the drain is insulated and that it doesn’t have any signs of damage or deformities.

CHECKING THE PERFORMANCE

The technician should wait until AFTER the cleaning to check the performance. That way, a dirty filter or blower wheel won’t be a potential cause of problems. The unit should run for about 15-20 minutes to give the components time to dry and equalize before the technician starts checking the performance.

Mini-splits don’t contain much refrigerant, so our techs try to minimize losses; they typically use probes or temperature clamps rather than gauge manifolds whenever possible. Technicians will also check the electrical components with their meters; they will ensure that the voltage and amperage are all within an acceptable range. While the unit runs, the tech will also check line temperatures and airflow as well as listen for abnormal sounds.

In some cases, we pull the refrigerant charge out of the unit and weigh it if the line temperatures seem off. If there is enough refrigerant, we’ll return it to the system. Sometimes, there will be too much refrigerant or too little; the technician may have to add or recover some refrigerant.

When the technician finishes, they’ll clean up the job site and have a conversation with you to close out the call. If you have any questions for them or comments about how they could have served you better, you can bring those to their attention. Once the system is running and all the tools have been cleaned up, the technician will be on their merry way.

So, a lot happens maintenance calls for ductless mini-splits. The procedure may take up to a few hours, but it’s necessary to keep your mini-split working at its best to keep your home healthy and comfortable. A good maintenance program is a key part of owning ductless mini-splits, and HVAC companies like Kalos can offer regular, thorough maintenance for your ductless mini-splits.

We also install mini-splits at Kalos Services; as a Mitsubishi Diamond Elite Contractor, we have access to top-notch manufacturer training and tech support. By getting installation and maintenance through us, you can be confident that you’ll experience the very best that Kalos Services and Mitsubishi have to offer.

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These units can heat or cool your home and run quietly, and we find that they tend to do a good job. However, they operate differently from your typical split HVAC systems. We’re going to cover some of the unique traits and common uses of ductless mini-splits to help you decide if they might be right for you. This article will also explain why you may want to call a Mitsubishi Elite Diamond Contractor if you decide that a mini-split is right for you.

INSIDE A TRADITIONAL HEAT PUMP SYSTEM

A traditional air-source heat pump isn’t a pump at all; it’s actually quite like a straight-cool A/C unit. However, a heat pump can reverse the refrigeration cycle to heat the home as well. Heat pumps provide heating by bringing outdoor heat inside the home.

In the cooling cycle, a heat pump uses liquid refrigerant (often called by the brand name “Freon”) to absorb heat from inside the home at the evaporator. That refrigerant vaporizes and goes to the compressor via the suction line. The compressor then raises the temperature and pressure of the refrigerant by squeezing it into a smaller space. Then, the refrigerant leaves the compressor via the discharge line and goes to the condenser. There, it rejects heat to the outdoors. (The refrigerant rejects heat because compression has made it hotter than the outdoor air; therefore, the heat naturally moves to the place with the lower temperature.) At that point, the refrigerant loses enough heat to become a high-pressure liquid, and it travels through the liquid line to a metering device, which drops the pressure. Metering devices tend to be TXVs or fixed-orifice pistons. From there, the cycle repeats itself.

In the heating cycle, a part called the reversing valve shifts the lines that go into and out of the compressor. So, the indoor unit (cooling mode evaporator) becomes the condenser, and the outdoor unit becomes the evaporator. The system absorbs heat outdoors and rejects it to the indoor space.

Heat pumps also have check valves, which route the refrigerant to one of two metering devices. Each operating mode uses its own metering device, and the check valves allow the refrigerant to bypass the device that is not in use.

INSIDE A DUCTLESS MINI-SPLIT 

Illustration credit: Craig Migliaccio (AC Service Tech; https://www.acservicetech.com/)

We can expect a typical ductless mini-split to have the same general refrigeration cycle as an ordinary heat pump. However, they often have a different type of metering device: an electric expansion valve or EEV.

EEVs are unique in that they rely on information from control boards to modulate themselves. Fixed orifices (pistons) can’t modulate at all, and TXVs are mechanical devices that respond to pressure from three different sources. Like a TXV, the EEV can modulate itself and change the size of its opening. The EEV differs from the TXV because it uses a stepper motor that gathers feedback from a control board, not three different forces, to adjust its opening.

In many traditional heat pumps, the metering device feeds directly into the evaporator. However, many ductless mini-splits have another line leading from the metering device to the evaporator; we call that the expansion line or flash gas line. That line takes the metered refrigerant (low-temperature, low-pressure liquid) and sends it to the evaporator coil. After the metering device, some of the liquid refrigerant will boil off due to the sudden pressure drop; that is called “flash gas,” and that’s normal in the expansion line and beginning of the evaporator.

Also, instead of having ducts to multiple regions of the home, a ductless mini-split focuses on conditioning the room where it has been installed. So, mini-splits tend to be good options for people who want A/C and heating in their sunroom or lanai.

DUCTLESS MINI-SPLIT UNIT CONFIGURATIONS

Nowadays, we can install ductless mini-splits in multiple configurations. It’s also worth noting that mini-splits can come in ducted varieties, but we will just discuss ductless ones.

Mini-splits may come in the form of high-wall units, which are mounted high up on the wall. There are also ceiling cassettes, which recess into the ceiling. (You can watch two Kalos installers set up a ductless Mitsubishi cassette system HERE.) There are even commercial ductless systems called variable refrigerant flow (VRF) systems.

In many cases, a one-to-one system with a single outdoor and indoor unit works just fine for a single room. That’s especially true of people who like to have heating and A/C in their lanais. However, there are also multi-zone configurations that place multiple ductless “heads” (indoor units) throughout the building. These ductless heads would all trace back to a single condensing unit outdoors. Bryan Orr, the president of Kalos, installed a multi-zone ductless mini-split system in his own home. You can watch what goes into the installation of an additional head below:

SPECIAL CONSIDERATIONS

Ductless mini-split systems are unique and will suit some people’s needs better than others.

One of the best aspects of the ductless mini-split is its efficiency. These units are all-electric and can have efficiency ratings of up to 30+ SEER; if you want to learn more about SEER ratings, check out our article about it at https://www.kalosflorida.com/air-conditioning/what-is-seer-and-why-does-it-matter/. These units have a very small carbon footprint and don’t take up much space in your home, either, so their compactness makes them appeal to people who want small units and care about energy efficiency.

The ductless mini-splits we install are also quiet. So, if you want to install a ductless mini-split in a place like a bedroom or home gym, you won’t have to worry about being bothered by a loud A/C unit.

More so than typical A/C units, ductless mini-splits work to condition their respective room. Although they may only require short runtimes, many mini-split units continue running at a low speed. That low speed typically isn’t enough to provide continuous dehumidification.

As a result, many ductless mini-splits come with a dehumidification mode, which runs the unit at a set speed on a timer to dehumidify the space. However, it’s not a great idea to rely on that mode alone for dehumidification; that mode may result in building occupants getting too cold and surfaces in the room reaching the dew point. In some cases, the condensation that forms on surfaces at the dew point may lead to microbial growth. You may need to consider investing in a dehumidifier in cases where the ductless mini-split can’t keep up with the indoor humidity. (Learn more about Kalos’s approach to installing whole-home dehumidifiers at https://www.kalosflorida.com/air-conditioning/do-dehumidifiers-really-work/.)

MAINTENANCE

As with any other type of HVAC system, ductless mini-splits require regular maintenance.

Ductless mini-splits are a lot more compact than most other split systems, so they generally contain a lot less refrigerant. So, even tiny leaks may have a noticeable effect over time. When our technicians check the charge of mini-split systems, we encourage them to use temperature clamps instead of gauges. We call that “non-invasive testing,” and we do it to minimize refrigerant losses.

If you have a ductless mini-split, you will also need it to be cleaned regularly. At Kalos, we generally remove the blower wheel, housing, filters, and vanes from the unit and clean those outdoors; we typically clean the indoor coil and drain pan in place using a plastic bib to catch the water and cleaner. (We also place drop cloths down and take extra care to avoid making a mess.) Cleaning the outdoor unit is also vital, so we take care of that, too. Soil buildup is normal, but it still needs to be addressed and taken care of by HVAC professionals. The chemicals we use to clean units are non-toxic and enzyme-based, so they shouldn’t harm or irritate anyone in the home.

During a PM, we will also check the electrical connections and amp draw while the system is running to ensure that the electrical side of the equipment is working well. If you have the time and would like to see how we do a PM, check out the video below.

Kalos Services is a Mitsubishi Elite Diamond Contractor, meaning that we work closely with Mitsubishi and stay up to date on their latest ductless mini-split technology and training. As a Diamond Contractor, we also offer free in-home consultations to help you decide which mini-split will work best for you. Working with a Diamond Contractor may also open you up to opportunities for extended warranties, rebates, and utility programs.

Whether you choose to use Kalos or another contractor to install a ductless mini-split, be sure to go with an accredited Diamond Contractor for the best installation process, financial opportunities, customer service, and consumer education.

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