Air Conditioning Is Not Working in One Room?

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Updated August 19, 2022

If you are new to the world of indoor cooling, you may wonder why your HVAC ducted air conditioner is not working in one room. Even the best air conditioners, after all, are still prone to certain maintenance and repair issues. So why do ductless AC units fail in one room and what can you do about it? Keep reading to find out why your air conditioner is not cooling the house.


  • When your ductless system stops working in a room, check to ensure that windows and doors leading to the room are closed and locked.
  • You should also check on the insulation, as a poorly insulated room is difficult to adequately cool, and change out the primary air filter.
  • Blocked vents also lead to poorly circulating air conditioning systems, so check the vents for obstructions and remove them accordingly to improve airflow.

What is a Ductless Air Conditioner?

As the name suggests, a ductless AC is an appliance that cools the entire home without using pre-existing ductwork. Installation is still expensive but the comfort and peace of mind are worth it. If you are wondering how long to cool a room with a portable AC, or with a ductless unit, it takes anywhere from 20 minutes to an hour. Ductless systems are highly efficient but are prone to certain repair issues, leading many to look up pertinent dual-zone air conditioning problems.

Insider Tip

Keep on track with cleaning or replacing air filters as indicated by the manufacturer.

Poor Insulation

If you have a poorly insulated room, the AC could struggle to cool it off during the hot summer months. It could over-extend its efforts and drive up your energy bills. Check the insulation and beef it up as necessary to ensure you have a positive cooling experience. Once fully insulated, if the unit is still not performing up to standards, try the below troubleshooting tips or learn if you need a permit to replace an air conditioner.

Coolant Issue

If your AC unit is having issues, check on the coolant, be it freon or some other method of operation. If the coolant is low, you might have a leak, so learn how to check a freon leak in a central air conditioner and a ductless system. Coolant-related problems plague every type of air conditioner if you are conducting a Whynter air conditioner review.

Open Windows and Doors

Keeping the windows and doors open in a specific room makes it harder for your AC unit to adequately cool the area. Keep the windows closed tightly while the AC operates, as even a small crack can impact the efficacy of the unit. While you are at it, lock the window, as engaging the locking mechanism ensures a tight and insulating seal.

Blocked Vents

Check to ensure your vents are free from obstructions so they can blow out cool air throughout the home. If you find an obstruction, such as debris or an item of furniture, remove it and check the room’s temperature once again.


No air coming out of one of the vents in your home?

It could be blocking in the air ducts or a clogged-up air filter, so check both accordingly. Check the air conditioning vent for debris and remove it.

Have you always had no/low airflow?

Before you can repair your system, try to remember if the issues are new or if they have always been a problem. Leaky ducts blocked air vents, and a malfunctioning air conditioning unit can impact air conditioning services throughout the home.

What is air balancing?

As the name suggests, air balancing refers to leveling out the airflow via air conditioning units throughout the home. This ensures that each room is free from cold spots and that each AC vent is working as advertised.

STAT: Any leak in a room is either pulling warm air in or allowing cool air to escape. (source)

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