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Stressed Woman Having Problems with Her Mini-Split at Home

10 Mar 2023

Author: Jeff O'Hara

Mini-split heat pumps have become increasingly popular over the last decade, becoming the HVAC system of choice for both new construction and home renovations. Widely in use in Europe since the 1980s, mini-splits were slow to get a foothold in the US market due to their bulkiness and noise levels that rival central HVAC systems. 

Leading up to the 2010s, mini-split heat pump makers continuously improved their products, increasing their already impressive efficiency ratings, size, and performance. These improvements have shown that mini-splits can effectively eliminate the need for bulky, noisy, and energy-devouring central HVAC systems; mini-splits do their jobs quietly, efficiently, and with little need for maintenance. 

Mini-Split Heat Pumps Have Their Weaknesses

As efficient and quiet as they may be, a mini-split AC is still an electrical and mechanical appliance made up of parts that are prone to possible failure over time. Mini-splits are smaller versions of a central HVAC system and use many of the same components, albeit in a smaller size. Compressor motors, evaporator coils, control panels, and air handlers can all experience issues, regardless of age or frequency of use. 

Most Common Mini-Split Problems.

Not Blowing Cold Air.

There are four reasons your mini-split doesn’t feel like blowing cold air into your house, two that can be solved by a crafty homeowner in minutes, and two that will require the help of a competent, professional HVAC company.

  • Incorrect Thermostat Settings

Electronic gadgets can play mind tricks on us. How many times have you felt your phone vibrating in your pocket, only to discover it’s on your nightstand? It’s entirely possible—and conceivable—that you have inadvertently set your mini-splits thermostat to “Heat” instead of “Cool.” We’re air conditioning experts, and even we’ve made this mistake in our homes and convinced ourselves that the unit or thermostat is broken. Save yourself an unnecessary service call, and make sure your system is in “Heating” mode.

  • Change or Clean the Air Filter

Checking on the air filter of your AC system is much more critical with a ductless mini-split. Central HVAC systems rely on large box filters stuffed with fiberglass to trap particulates and clean the air for the entire home. It’s normal to leave a central HVAC filter unchanged for six months to a year and not even notice a performance difference, but your mini-split system has different needs. 

Mini-splits use air filters that are comparable to the pull-out lint filter in your clothes dryer. The filter in your mini-split is easily accessible and simple to wash on purpose, solely to encourage us lazy homeowners to get off the couch and at least clean our HVAC filter once a month. 

Jokes aside, keeping up with filter maintenance will go a long way regarding the longevity of your mini-split. Yes, they’re smaller and use less energy, but they also work much harder than their central HVAC ancestors. Smaller compressors and blower motor fans must achieve significantly higher RPMs to accomplish their job, putting tremendous strain on bearings and other components. 

  • Refrigerant Leaks

The liquid refrigerant circulation system is a “closed loop” setup designed to retain and use the same refrigerant installed in the factory until it reaches the end of its useful life. Unscrupulous air conditioning companies will tell you that you need to “charge” your HVAC system with Puron (or Freon for older systems) as a normal part of AC maintenance. This is false. If your air conditioner is low on liquid refrigerant, the only cause is a leak, and any HVAC tech that is content to simply recharge an AC system with refrigerant without working to discover the source of the leak is not worth your business.

  • Blocked Condenser Coil

In a mini-split heat pump, the condenser coil is responsible for removing the heat that has been drawn into the unit from the house and dispersing that heat outdoors. When your mini-split’s regular maintenance has been neglected, particles lodged in the air filter can be drawn into and trapped in the condenser coil. If enough debris finds its way into the coil and impedes refrigerant flow. Also, since the condenser coil is located outside, you’re certain to find all kinds of leaves, twigs, bird’s nests, and all sorts of junk that only serve to reduce airflow around the condenser coil, which is key to the cooling and heating processes.   

It’s Always Humid in the House.

It doesn’t seem to matter how many hours a day you run your mini-splits to cool your home; you just never get rid of that heavy, clammy feeling that only excess humidity can provide. 

  • Your System is Working Too Hard

Try turning the fan speed down. Your mini-split system should have the option to select the speed at which the blower fan runs, usually low, medium, and high. By running the system at a lower speed to achieve the set temperature on the thermostat, the system will have to run for a little longer. The extended “on” cycle permits more of your indoor air to be drawn out of the house, taking the excess moisture with it. 

  • Your Air Filter Requires Attention

Clogged air filters are at the root of almost every issue that is based on poor HVAC performance. Check to ensure your filter is clear of any dust or debris, and if you have a foam or other porous filter, check that it hasn’t gotten damp. Soggy air filters can be a sign of condensate drainage problems (see the next section) that can add to humidity and must be checked out as soon as they’re discovered.

  • You Have a Single-Zone Mini Split

Too much humid air may encroach from other areas of the house not serviced by the mini-split. The best solution is to add an additional indoor air exchanger in the affected room(s) that can all be connected to the same outdoor compressor unit.

Not Draining Condensate Water.

Your mini-split AC spends all day pulling hot air and humidity out of your home, and while the heat is discharged into the outdoor air, humidity is liquid. Your AC system needs somewhere to put that liquid, so it doesn’t cause any damage. 

  • Water Leaking from Air Handler

When the condensate drain line becomes clogged –which can happen, making regular maintenance crucial—water has nowhere to go except to back up into the indoor handler. Water leaks from ductless mini-splits can damage walls, floors, and carpets and cause foundation issues, particularly in pier-and-beam foundations. 

  • Something Smells Funny

When coming out of your air conditioning system, mildewy, funky smells are never good and spell trouble. The problem could be as simple as needing to attend to the filter and either clean or replace it—based on your manufacturer’s instructions—and then reassess the situation. If the odors continue or start to get worse, please call a professional HVAC company for assistance. Air handler leaks that are left unchecked can cause thousands of dollars’ worth of damage in hours. 

What Mini-Split Problems Can I Fix Myself?

Mini-split heat pumps are much easier to work on for HVAC technicians, which translates into lower repair costs than central HVAC systems. With a central HVAC system, there’s a list of things the homeowner can check to either repair the issue themselves or better inform their service tech. Mini-splits are essentially non-user serviceable. If your problem continues beyond cleaning and replacing the air filter, you’ll be best served to call in a HVAC company for professional AC repair.

Call Nick’s Air Conditioning for Help with Your Mini Split Misery.

Ductless mini-split heat pumps have been the first real innovation in the home comfort industry since the introduction of central HVAC systems in the 1960s. Still, problems occur, some of which might not even require an in-home service call; we may be able to help over the phone. If you’re experiencing anything unusual about the operation of your mini-split system, from strange noises to water leaks, call Nick’s Air Conditioning right away…and turn the offending air handler off.

Call Nick’s Today. We’re on the Way!

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