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Ductless air conditioners, also called mini-split ACs, are more energy efficient if you usually need one or a few rooms cool in your house. A ductless air conditioner also improves indoor air quality. However, if your mini-split unit is acting weird or not working, try the fixes shown in this guide.

Fix Mini Split AC Problems

Mini Split AC Won’t Turn On

If your mini split AC is not turning on, their many things that can trigger this. So, you inspect these things:

Check The Power And Breaker

Make sure that your house has power and the AC is receiving power as well. If the AC recently tripped, check the circuit breaker and make sure that it’s at the ON position. Moreover, check other switches and cords as well to ensure that they are connected, not damaged, and at ON positions.

Replace The Remote Batteries

Many times, the cause of a mini split not working is drained remote batteries. To replace the batteries and try to turn on the AC again.

Dormancy Issue

If your mini split AC was not used in the winter. It may not turn on right away if you switch it on in the summer. The reason is dust buildup on fans, evaporator coils, air filters, condenser unit, and other parts of the AC. Therefore, hire a mini split AC expert to clean the air conditioner and check for any repairs as well.

Keep in mind that you should always prepare your AC for summer by cleaning it thoroughly before beginning its use in the summer.

The AC Capacitor Is Faulty

Any electric device that has a motor requires a capacitor for starting it. If your AC is not turning on, abruptly turns on and off, or your AC doesn’t cool, the capacitor may be malfunctioning. An AC capacitor should be replaced by an air conditioner technician.

Moreover, the technician will also check why the capacitor failed. If your AC is not too old, this aspect should be investigated as well. Commonly, capacitors malfunction due to the overheating of the AC unit or power fluctuations.

The AC Has Reached The End Of Its Lifespan

Mini split air conditioners last for 12 to 15 years. If you maintain them well, they may even reach the 20-year mark. However, once your AC has reached its end of life, It will show problems not failing to turn on, the compressor not switching on, not cooling or inadequate cooling, refrigerant leaks, and other problems.

Moreover, if your AC is requiring repairs too often, it’s a clear sign that you should avoid spending money on repairs and replace your mini split system.

Mini Split AC Is Not Cooling

If your ductless AC is not cooling or not blowing cold air, you should check these things:

Wrong Thermostat Settings

In some cases, the cause of the mini split not cooling is incorrect thermostat settings. Check the settings and make sure that they are lower than the current room temperature if you aim to cool the room.

Moreover, if you have a heat pump, you should check if the settings are on heat mode. If it is, then switch to cool mode.

Dirty Air Filters

Dirty air filters is a common reason for a mini split not cooling or blowing warm air instead of cool air. Therefore, check the air filters and clean them regularly.

Keep in mind that dirty air filters can cause serious problems if left uncleaned. They can cause airflow problems, clogged condenser coils, and other issues. So, prevent these problems by cleaning air filters once every two weeks.

Clogged Evaporator Coils

Evaporator coils convert from warm air indoors to cool air. In mini split air conditioners, they are located under the air filters inside the indoor unit. If air filters are not cleaned regularly or the last cleaning of evaporator coils was a year ago, the reason for cooling issues can be clogged evaporator coils.

You can clean evaporator coils using a brush or a coil foam cleaner. However, leaving it to an AC expert is better to avoid damage to the coils during cleaning.

Low Refrigerant

Low refrigerant levels can cause many problems including AC not cooling. Unless you’re using your mini split AC after many months, the cause of low refrigerant is usually a leakage.

If your mini split doesn’t reach the set temperature, hissing or bubbling noise, ice on refrigerant lines, or your power bill is higher than normal then the refrigerant of your AC is low.

Anything related to AC refrigerants should be fixed by a certified professional. Before filling the refrigerant, an expert will inspect the AC for leaks and fix them.

Clogged Condenser Unit

The condenser coils inside the condenser unit of a mini split AC release heat collected from the inside to the outside. If the condenser coils are dirty, they won’t perform their job correctly and the AC won’t cool properly. Therefore, clean the outdoor unit of the AC including the condenser coils in it.

Malfunctioning AC Fan Motor

Another reason for a mini split not cooling is a malfunctioning fan motor. It’s located near the evaporator coils inside the indoor unit. If the fan motor is bad, you may experience no or insufficient airflow, the fan not starting at all, weird noises like rattling, humming, or buzzing, and warm air instead of cool blowing from the air handler.

So, consult air conditioner repair services Stony Brook who can check your mini split for fan motor problems and other issues if the AC is not cooling.

Mini Split Is Noisy

If your AC is making weird noises, you check what kind of noise it is to find the correct solutions.

Banging Noises

  • Dirty condenser coils or condenser unit. Sometimes, it’s due to some leaves or shrubs getting into the condenser unit.
  • Loose screws inside or outside the air conditioner unit can cause a banging noise.
  • Faulty fan motor.
  • Malfunctioning compressor.

Screeching Noises

  • Faulty fan motor bearings.
  • Broken or worn-out belt.
  • High pressure developed inside the compressor. You must turn off your AC immediately if you hear screeching or squeaking noises to avoid an explosion.

Pulsating Noises

  • Loose fan blade.
  • Loose coils.
  • The plastic base of the AC could be pulsating.

Hissing Noises

  • Most commonly, hissing noises are heard when the refrigerant is leaking from the refrigerant lines.
  • Compressor valve leak. It controls the pressure of the refrigerant. You must consult an HVAC expert immediately.
  • High pressure inside the compressor. You must turn off AC immediately and consult an expert.

Clicking Noise

  • Obstruction in AC fans.
  • Loose fan and hitting the case of the condenser unit.
  • The capacitor inside the unit loses its charge or malfunctioning.
  • Electrical signal problems. If you see sparks as well with a clicking noise, turn off the AC immediately.
  • A faulty thermostat can stop the AC from turning on resulting in repeated clicking sounds.

Humming Noise

  • Bent fil coils.
  • The motor doesn’t have enough lubricant making a humming noise.
  • Contactor failure. A contactor controls the flow of electricity to the AC. With a contact issue, the AC receives power but doesn’t turn on resulting in a humming sound.


One issue can be caused by various problems. So, if your mini split AC is not working, not cooling, or showing any other problem, get in touch with AC repair services Huntington for inspection and repairs or replacements.


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