Why is my Air Conditioner Not Cooling the House?

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Updated June 29, 2022

If you are new to the world of indoor cooling, you may ask yourself “why is my air conditioner not cooling the house.” Even the best air conditioners, after all, can fall victim to issues that impact performance. So what are the major causes of AC unit malfunction and what can you do about it? Keep reading to find out.


  • AC units struggle to cool homes for a number of reasons, including a dirty air filter, a frozen evaporator coil, a refrigerant leak, or even a malfunctioning heat pump.
  • You should also check the thermostat to ensure it is set to your desired temperature, which is a simple fix.
  • For central AC units, head to the outdoor unit to the compressor and clear it of debris such as sticks, leaves, and dirt.

Why do Air Conditioners Struggle to Cool Homes?

There are many reasons why air conditioners fail at their primary task, leading some to learn how to fix AC units and others to learn maintenance tasks. It is also helpful to learn how an air conditioner works as part of the troubleshooting process. Here are some of the most common reasons why AC units struggle with cooling a whole house, so you can learn why a ducted air conditioner stops working in one room, along with other relevant queries.

Insider Tip

Another easy troubleshooting task is cleaning all major components of your air conditioning unit.

Dirty Filters

When learning how to clean a window air conditioner, or maybe cleaning a portable air conditioner, or any AC unit, you tend to hear the same thing over and over. Replace or clean the filter according to the manufacturer’s instructions. Dirty filters lead to clogs, which drastically reduce the efficiency of the unit. In addition to improving the efficacy of your AC, keeping the filters properly maintained helps eliminate nasty odors, so you won’t have to wonder why your air conditioner stinks when you turn it on.

Check the Thermostat

If you are wondering how often you should service an AC unit, the answer is once a year or when issues arise. However, there may be one simple reason why your AC is struggling to adequately cool your home. Check on the thermostat to ensure it is set to your preferred temperature. If the thermostat is set too high, for instance, the AC or central air conditioner will never have cause to turn on and emit cool air. This is a simple and easy fix.

Blocked Condensor Coils

If you have a central AC with an outdoor condenser, take some time to check on the condenser coils to ensure there are no issues. When these coils become enmeshed with debris, such as sticks or leaves, it severely impacts the performance of the air conditioner. Clean away any debris with a vacuum with a brush attachment, going slowly so as to not damage any crucial components.


Why is the AC not blowing cold air?

There are a number of reasons why an AC unit stops blowing cold air, from a dirty filter to a broken condenser coil.

Should I turn off the AC if it’s not cooling?

It is helpful to power down the air conditioning unit to troubleshoot, so yes turn it off when it is not cooling. Next, check on the thermostat settings and follow the steps listed above.

How do I reset my air conditioner?

This depends on the make and model of your AC and any attached accessories, such as a heat pump. The process typically starts by approaching the air conditioning unit or central air conditioning system and following the prompts.

STAT: Typical split-system air conditioners have a lot of moving parts, including an indoor air handler unit (furnace or fan coil), an evaporator coil, air filter, thermostat, and copper tubing (refrigerant lines) that connect the indoor and outdoor units. (source)

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