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Is Your Ductless System on the Fritz? Troubleshooting Tips Before Calling the Pros

Ductless systems are high-tech heating and cooling equipment that employ sophisticated components to power the simple principle of heat energy movement from a warmer place to a cooler place. When all components are functioning smoothly and leveraging maximum heat exchange from the refrigerant, your ductless heating and cooling system delivers comfortable temperatures and high efficiency performance at the right price in any season.

On the other hand, it is possible that ductless issues arise from external factors, such as deficient installation, inadequate care and environmental hindrances, which can complicate and obstruct the heating and cooling functions and cause your ductless system to act up. If that's the case, use this guide to see if a simple solution can be found before calling a certified pro.

Simple Principle

Ductless heating and cooling systems leverage the principles of heat energy movement by placing high efficiency refrigerant through a series of pressure and temperature changes. By understanding the basic operation of heat extraction, movement and transfer, you may better identify system trouble when it arises.

  • The compressor, which is housed in the cabinet located outside the home, squeezes refrigerant to prepare it for heat extraction.
  • The refrigerant flows from the compressor to a heat-exchange coil, which may be the indoor coil located in an air handling unit (AHU) or may be the coil located in the outdoor unit (depending on if the ductless system is in cooling, heating, defrost or de-humidification cycle).
  • Inside the coil, the refrigerant is condensed to a hot liquid state and transfers heat energy to the surrounding air with the assistance of a fan.
  • The refrigerant, depleted of usable heat energy, flows to a second heat-exchange coil.
  • The liquid refrigerant flows into the coil under low pressure and evaporates, becoming extremely cold.
  • As the cooled refrigerant evaporates, it extracts heat energy from the air with the assistance of a second fan.
  • The refrigerant returns to the compressor to continue the selected cycle.
  • Note: a reversing valve is utilized in ductless heat pumps (not cooling-specific units), which controls the direction flow of the refrigerant, allowing it to extract, move and transfer heat energy at both coils.

Simple Solutions First

The steps outlined for ductless system heat-energy exchange are the basic operating principle of any air-source heat pump and cooling-specific system. So, if your ductless heat pump or A/C is acting up, the troubleshooting tips are similar regardless of ductless model. The ideal solutions to ductless issues are simple solutions that you can perform yourself. If the issue at hand involves any of the following factors and components, you may be in luck with a quick and simple do-it-yourself solution.

  • Power - The AHUs are linked to the outside unit via a thin conduit, which houses the power cable, refrigerant line and drainage tubing. If the AHU isn't powering on, check to see if the outside unit is running. If it's not, check the circuit breaker to see if it has flipped. If you have a Mitsubishi Electric ductless system, the unit should restart after a power failure or after turning on the circuit breaker. If the circuit breaker isn't the issue, there's either an electrical issue which should be handled by an HVAC professional, or an issue with the thermostat function or communication with the system.
  • Air filter - If the power and temperature are fine but airflow is weak, check the air filter. A clogged air filter is an airflow obstruction and poses all sorts of issues for overworking components and causing excessive energy consumption, in addition poor air cleaning and filtration performance. Slide the air filter out from its slot or remove the AHU cabinet, depending on your ductless system. If the air filter is dirty, rinse it clean with warm water. Let it completely air dry before re-inserting it.
  • Temperature and airflow - If the ductless system has power but the airflow temperature isn't comfortable, make sure the thermostat is set to the correct cycle and at an appropriate temperature. Your ductless system may not have automatic switch-over between heating and cooling cycles, which can sometimes lend to incorrect temperature and cycle settings.

    Another possibility for poor temperature performance is an obstruction to airflow at the outside unit. Since the indoor fan is housed in the AHU cabinet, there are essentially no potential obstructions except for a dirty air filter. However, the outside unit is exposed to the elements, strewn leaves and debris, and other objects which can easily obstruct airflow.

    Poor airflow results in inadequate refrigerant heat-exchange, which places an enormous burden on the ductless system. Make sure the outside unit is free of any airflow obstructions. You may remove the access panel and clean inside. Dirt, grass clippings and other debris eventually find their way in.

  • Noise - A noisy ductless system is a discomfort which no one wants. The primary noise maker of any air-source heat pump is the compressor. If the compressor to your ductless system is located directly opposite the wall of the space you're conditioning, it may make enough noise to be an issue, especially if it's in need of a tuneup. If there's room inside the cabinet, you may try installing a sound-absorbing blanket, which is available at some home-improvement stores.

    If the noise is coming from the AHU, it may be a rattling fan or perhaps the AHU cabinet isn't fastened on securely. A noisy fan indicates excessive debris, excessive wear, worn components or damage. If the fan is dirty, wipe it with a clean cloth. Otherwise, your HVAC pro should take a look to resolve the problem.

  • Odors - Household odors may originate from a number of sources, including cooking smells, tobacco odors and mold and mildew. The coil inside the indoor AHU is susceptible to accumulating mold and mildew growth and subsequent odors.

    Also, tiny particles associated with tobacco smoke and other contaminants may accumulate on the wet coil and other components, especially if the air filter isn't checked regularly or if it's a poor quality filter. To help rid the AHU of odor-causing contaminants, replace the air filter and wipe the heat-exchange coil clean of any debris, mold or mildew.

Certified Professional Care

Ductless heating and cooling systems require regular professional maintenance in order to perform at peak efficiency season after season. While the principles of heat exchange are the same for ductless systems as for any other air-source heat pump or A/C system, ductless units require professional care specific to the high performance components they employ. If you have a Mitsubishi Electric ductless system, your Mitsubishi Electric Diamond Contractor has special certification for your system.

These are the primary areas which are inspected and tested during professional maintenance:

  • Power - All cycles heating, cooling, defrost and de-humidification—are tested.
  • Airflow - Airflow is checked at each AHU and at the outside unit. The air filtration system is inspected and cleaned as necessary.
  • Temperature - Thermostats are checked for proper function. Electronic sensors scan the room top to bottom for temperature variances. All electronics and sensors are tested to ensure proper function, temperature monitoring and super-cooling and super-heating regulation.
  • Refrigerant - Mitsubishi Electric ductless systems use high efficiency R410A refrigerant. Refrigerant charge is checked to ensure optimal heat exchange, home comfort and energy efficiency.
  • Odors - The coil in each AHU is deep cleaned to remove debris and mold spores. In addition to preventing odors, this also boosts efficiency by allowing for direct contact between air source and coil which promotes optimal heat exchange.
  • Drainage - Drainage is checked at the outside unit and at the indoor AHUs. If there's an issue with mold, the drainage line may be chemically treated to prevent mold, algae and other contaminants.
  • Piping - Any accessible conduit, or Mitsubishi Electric two-piping system, is inspected for damage or drainage leaks.

Performance Installed

Many ductless performance issues originate from a poor quality installation. To maximize your investment dollars, select a high-quality ductless system that delivers a nice return on investment with low energy bills, minimal maintenance and built-to-last components, and choose an HVAC professional that knows exactly how to install your ductless system. Only your Mitsubishi Electric Contractor is licensed and certified by Mitsubishi Electric to install such systems. That's very good news for your investment dollars, home comfort, energy budget savings and peace of mind.

If your ductless system is on the fritz and you need help with troubleshooting the issue, or for more information about installing a Mitsubishi Electric ductless heat pump, give us a call to connect with a certified Mitsubishi Electric Contractor near your Virginia home.

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