The hot summers, moderate autumn and spring seasons, and mild winters in Lake Elsinore, CA mean that your air conditioner gets a lot of use. This heavy workload for your cooling system may occasionally lead to a problem. If you notice hot air blowing out of your home’s air vents while your air conditioner is running, one of these six causes may be to blame.

1. Dirty Air Filter

The top reason why air conditioners blow hot air is a dirty filter. Dirty filters reduce airflow. Less of your home’s air can reach the cold evaporator coil, so the system just blows the same warm air back into your living area. This eventually results in the evaporator coil getting too cold. A frozen evaporator coil could trigger the AC unit to shut down, and the coil may develop damage if it gets too cold. We recommend inspecting the HVAC filter each month. As soon as you see dust and debris on it, replace it. Be sure to change the filter at least every three months.

2. Incorrect Thermostat Setting

Verify that your thermostat is on the correct setting. If someone put the thermostat on “fan only,” the AC unit will just circulate the warm air in your home. If you have central heating and cooling, the “auto” setting could also trigger the heating system to cycle. Put the thermostat onto “cool.” Lower the temperature setting by a few degrees, and wait to see if cold air blows out of the vents.

3. Refrigerant Leak

A refrigerant leak is another common cause of air conditioners blowing hot air. Over time, the hose, tubing, or valves in the closed-loop system may degrade. This allows some refrigerant to leak out of the system. With less refrigerant, the evaporator coil doesn’t get as cold. The unit can’t absorb as much heat from your home’s air, and the air blowing out of the vents won’t feel cold on your skin. If too much refrigerant leaks out, the system’s safety switch will prevent it from cycling. Only an HVAC service technician can measure the refrigerant level. Any leaks must be repaired before the system can be recharged with more refrigerant.

4. Malfunctioning Compressor

A problem with the AC’s compressor may lead to warm air blowing out of your home’s vents. The compressor’s job is to compress the refrigerant from a gaseous state into a liquid state. The refrigerant then goes to the condenser, which removes the heat from the refrigerant. The cold refrigerant then travels to the evaporator coil. If the compressor isn’t working properly, the refrigerant won’t turn into a liquid, and it won’t be able to complete a cooling cycle. A compressor failure is a costly repair, and if your air conditioner is old, you might be better off replacing it with a new, more efficient cooling system.

5. Dirty or Frozen Coils

A dirty or frozen evaporator coil may lead to your AC unit blowing hot air. When the warm, moist air in your home can’t come into contact with the cold evaporator coil, there’s no way for it to drop in temperature. The air handler will blow the warm air back into your living space. Routine AC maintenance prevents the evaporator coil from developing dust and debris thick enough to interfere with the unit’s performance.

6. Defrost Cycle

The only normal time for warm air to blow out of your home’s air vents during a cooling cycle is when the system runs a defrost cycle. A couple of times each day, the air conditioner may perform a brief defrost cycle in order to reduce or eliminate ice buildup on the evaporator coil. A defrost cycle is essentially a reverse cooling cycle. It only lasts for a couple of minutes. The unit should then return to proper cooling. If your air conditioner continuously blows hot air, it needs an inspection and a repair performed by a qualified service technician.

In addition to air conditioner repairs, our skilled technicians at Polar Express Plumbing, Heating and Air Conditioning also offer heating system repairs and heating and cooling replacement, installation, and maintenance. Our humidification, air purification, air filtration, and QuietCool whole-house fans improve your indoor comfort and air quality. We also offer maintenance agreements for your peace of mind. For more information about why air conditioners blow hot air or to schedule an air conditioning system repair service in Lake Elsinore, reach out to the team at Polar Express Plumbing, Heating and Air Conditioning.

Meet the Author
Anthony Dieringer
Anthony Dieringer

company icon