Why is My AC Running but Not Cooling the House?

As an HVAC expert, it’s a common issue that clients come across – the air conditioner is running, but it’s not cooling the house effectively.

This problem can be caused by numerous factors, from refrigerant leaks to dirty air filters.

Understanding the potential causes can help you find a solution quickly. This article will explore some of the most common reasons for this issue and provide you with guidance on what to do next.

10 Reasons Why Your AC is Running But Not Cooling The House

  • Refrigerant Leak: If your air conditioning unit is low on refrigerant, it may struggle to remove heat energy from your home. Fix: If you suspect a refrigerant leak, call an HVAC professional. They can safely replenish refrigerant levels and repair any leaks in the refrigerant lines.
  • Dirty Air Filter: A clogged air filter can restrict air flow, causing your AC to work harder and cool less effectively. Fix: Regularly check and replace your air filters to maintain proper airflow.
  • Frozen Evaporator Coil: Insufficient airflow can also cause the evaporator coil to freeze, leading to a less efficient cooling system. Fix: Regular air filter changes can prevent this, but if the coil is already frozen, you’ll need an HVAC professional’s assistance.
  • Dirty Coils: Over time, both the indoor coils and outdoor coils can get dirty, reducing their ability to transfer heat. Fix: Regular cleaning of the condenser coil and evaporator coil can improve your AC’s performance.
  • Thermostat Issues: If your thermostat is incorrectly calibrated, it may cause your air conditioner to turn off before your home reaches the desired temperature. Fix: Check your thermostat’s settings and ensure it’s working correctly. Replace if necessary.
  • Circuit Breaker Issues: If the circuit breaker connected to your AC unit has tripped, your AC may still run but fail to cool your house. Fix: Check your breaker panel and reset the circuit breaker if necessary. If it keeps tripping, call a professional.
  • Duct Leaks: If your air ducts have leaks, cool air could be escaping into unused spaces like your attic, reducing the airflow in your living spaces. Fix: Sealing air duct leaks can improve the efficiency of your air conditioning system.
  • Improper Installation: If your central air conditioning system isn’t sized or installed correctly, it may struggle to cool your home effectively. Fix: If you suspect this is the case, contact an HVAC professional to assess your system.
  • Compressor Malfunctions: The compressor is crucial for cooling your house by circulating refrigerant. If it’s malfunctioning, your AC won’t cool effectively. Fix: Compressor issues typically require professional repair or replacement.
  • Dirty Return Vents: Dirty or blocked return vents can restrict air flow, hampering your AC’s cooling power. Fix: Regularly clean and check return vents for any obstructions.

Why is My AC Not Cooling Below 75 Degrees?

Your AC might not be cooling below 75 degrees due to low refrigerant levels, a malfunctioning thermostat, or issues with the outdoor unit. Other potential causes include a dirty air filter, a refrigerant leak, or a frozen evaporator coil.

Why is my AC not Cooling After a Filter Change?

If your AC isn’t cooling after a filter change, it could be due to improper installation of the air filter, a thermostat issue, or a tripped circuit breaker.

Why AC isn’t Cooling to Set Temp?

If your AC isn’t cooling to the set temperature, potential causes include a dirty or frozen evaporator coil, issues with your thermostat, or problems with your heat pump or outdoor condenser unit.

What to do if AC is Not Cooling?

If your AC isn’t cooling your home, first check the most common issues – the thermostat settings, circuit breaker, and air filter. If you can’t identify the issue, it’s time to call an HVAC technician.

When to Call an HVAC Technician for Repair?

Call an HVAC technician if your AC isn’t cooling and you can’t identify the cause, or if you suspect serious issues like a refrigerant leak or compressor malfunction. Regularly scheduled professional maintenance can also help prevent many common problems.


There are many reasons why your AC might be running but not cooling your house effectively. In many cases, the fixes can be simple, such as replacing a dirty air filter or resetting a tripped circuit breaker.

However, some problems, like refrigerant leaks or compressor malfunctions, require the skills of an HVAC professional.

Regular maintenance can help keep your air conditioning system working efficiently, reducing energy bills and increasing your home’s comfort level.

About Roy Cohen

Roy Cohen has a burning passion for heating, cooling, and ventilation. He aims to help you save money on expensive repairs and bring you the best HVAC products. He has years of experience behind him in HVAC repair and garage maintenance.

You can find Roy at his LinkedIn or his email: [email protected]

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