In the dead heat of summer, the last thing you want to deal with is a malfunctioning A/C unit. One of the most common problems that occur with air conditioning systems is the output of hot air instead of cold. Obviously, that’s an issue that needs to be fixed right away!

What Are Some Common Causes of an A/C Unit Blowing Hot Air?

There could be a number of reasons why your A/C unit blows hot air out of the vents when you want it to blow cold. These include the following issues:

  • A malfunctioning thermostat. If your thermostat is not properly calibrated, then it may think that the ambient temperature is colder than it actually is. It will try to heat up your home, instead of cool it down like it should.
  • Dirty evaporator coils and/or air filter. An A/C system’s air filter in itself has nothing to do with whether the unit blows hot or cold air. However, a dirty air filter could lead to dirty evaporator coils — and when your evaporator coils are dirty, clogged, or covered with debris, there may not be enough free air flow for proper cooling operations to take place.
  • Refrigerant leak. Perhaps the most common reason why an A/C unit starts blowing hot air instead of cold is a refrigerant leak. Without enough refrigerant in the system, there’s no way to adequately cool the warm air that the system draws in.


If you are dealing with an A/C unit that only blows hot air, then the friendly HVAC experts at HALLTEC can help. We can provide an accurate diagnosis of the problem, walk through the steps we’ll take to fix it, and then deliver high-quality repair work in a timely manner. Reach out to our team today to learn more.