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Is Your Ductless A/C on the Fritz? Troubleshooting Techniques

Some HVAC repair jobs are do it yourself, but not all.Is your ductless A/C on the fritz and not performing up to its normal cooling capacity? Are you installing a new ductless system for the first time and want to get it right? Then you've landed on the right page. Keep reading to learn how to troubleshoot ductless cooling issues, whether they're caused by a technical glitch, maintenance issue, environmental factors or installation matters.

Basics of Ductless Cooling

Ductless A/C systems provide energy efficient cooling by extracting heat energy from the air inside the home at the indoor air handling unit (AHU). The heat energy is transferred and released to the outside air at the outdoor AHU. These are the same refrigeration principles used by conventional central A/C systems, but with redesigned and different components. Following are the basic elements of ductless cooling:

  • Airflow - Like central A/C systems, ductless A/C systems require free airflow across the indoor and outdoor heat-exchange coils (evaporator and condenser).
  • Filtration - Air is pulled into the AHU through Mitsubishi’s advanced filtration components, which capture contaminants before they can reach sensitive components. They also prevent the contaminants from re-circulating back to the zone.
  • Heat transfer - Air is pulled across the evaporator coil, which helps instigate the movement of heat energy from warm air in the living space to the extremely cold refrigerant inside the coil.
  • Piping (no ducts) - Refrigerant flows from the indoor AHU to the outdoor AHU via a thin conduit. The conduit is the design element to ductless cooling that makes ductless systems refrigerant distribution systems rather than air distribution systems like ducted central A/Cs.
  • Heat sensors - Sophisticated sensors continuously monitor temperatures at the coils, return air and zone, and adjust cooling output in real time for continuous comfort.
  • Drainage - The condensate line is contained inside the conduit with the refrigerant and power lines. It removes moisture which collects on the indoor coil. (This is an important element of ductless cooling which to properly maintain to prevent water leaks inside the home.)

Troubleshooting: From Fritz to Fixed

If your ductless A/C is on the fritz, then perhaps you should hear the good news first. Many common operational issues with any A/C system, whether ductless or ducted, are issues that may be dealt with before calling your HVAC professional.

  • Power - If the ductless system doesn't power on even though the thermostat settings are correct, check the circuit panel for a tripped breaker.
  • Airflow restrictions - Have you checked the air filter lately? Clogged air filters are common issues that contribute to increased wear and electricity consumption and can restrict airflow to affect cooling capability. Clean or change the air filter monthly, particularly during peak usage of the cooling months.
  • Airflow temperature - Make sure the thermostat setting is a few degrees above room temperature. If the unit isn't cooling airflow properly, remove the cabinet to see if the coil has iced up. Poor airflow or incorrect refrigerant charge will cause ice accumulation on the indoor coil. This is a serious issue that can cause drainage issues (melting ice carries debris down the condensate line) and makes the compressor work much harder. Turn the unit off and allow the ice to melt. If the ice accumulation occurs again after you have cleaned the filter and checked the outside unit for debris, call your HVAC pro.
  • Noises - Noise is a nuisance no one wants. A noisy ductless A/C, which is typically very quiet, is a sign of a compressor problem. This is a sign the system needs a tuneup. If the noise is coming from the indoor AHU, such as a rattling noise, the cabinet may simply be loose or the fan could be out of balance due to wear or debris accumulation.
  • Odors - A/C systems must deal with moisture in the form of condensate on the indoor coil. If your ductless A/C was installed by a knowledgeable professional, the condensate pan, pump and line should all work with no issue. If your system hasn't had a tuneup in recent memory, the drain line could be harboring bacterial and mold growth, which can create foul odors directly inside the living spaces. Remove the cabinet and clean the coil with a soft cloth.

Mitsubishi ductless A/C systems are designed to operate efficiently and last for years as long as they receive regular care. If you're having issues with your system beyond these troubleshooting tasks, please contact us to be connected to a Mitsubishi Electric Contractor near your Virginia home.

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