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What Can Cause My AC To Blow Warm Air

December 29, 2025
ac blowing warm air

Summer season is when we count on our air conditioners the most, especially on the hottest of days. One of the most common requests for AC repair during the summer a homeowner will face is an ac blowing warm air. In this article we will review the most common reasons for why an air conditioner will suddenly blow warm air. We will also share a few troubleshooting steps in Northridge you can take to possibly avoid waiting for an HVAC technician.

Thermostat

The first thing you want to check when you notice your AC blowing warm air is your thermostat. Sometimes, the issue could be caused by something as minor as the wrong thermostat setting. It could be that the thermostat was accidentally set to heat instead of cool. Also, check to make sure it is set to AUTO and not ON. The ON setting will keep the blower fan running all the time even if the AC or heater is off. Additionally, you want to make sure the batteries are working, check and replace them if needed.  

Circuit Breaker

After you have checked your thermostat, make sure the system has power. There are times when the circuit breaker may shut off power automatically due to too much demand as a safety precaution. Check your electrical panel and look for a tripped breaker. Simply switch the breaker completely to off position and then flip it on. However, if the breaker continues to trip then contact a professional.

Dirty Air Filters

A dirty air filter will lead to restricted airflow. This leads your air conditioner to work overtime and puts extra unnecessary strain on your system which could lead to early failure.  One of the first things you will want to check when your ac is blowing warm air is your air filter and ensure it is clean. Check your filter often during the summer months and replace when dirty.

Dirty or Frozen Evaporator Coils

A dirty or frozen evaporator coil may be the reason behind your ac blowing warm air. The primary cause for a dirty or frozen evaporator coil is a dirty air filter. A clogged evaporator coil will not allow for enough airflow for proper cooling. If your evaporator coil is frozen, turn the unit off replace the air filter and wait until it is completely thawed out before turning the unit back on. If the coils freeze up again, then contact a professional to diagnose and complete any necessary repairs.

Clogged Condenser Coils

The outdoor and indoor components of your ac system work together to cool your home. If the outside unit or the condenser is clogged with dirt and debris, it will remove heat effectively. To prevent this from happening keep your outdoor unit clean and clear of any debris or foliage. This can be completed during routine ac maintenance.

Low Refrigerant Levels

One of the main culprits for your ac blowing warm air is low refrigerant levels. Refrigerant is responsible for absorbing heat from your home’s air. If there is a refrigerant leak present your ac will struggle to cool your home. Symptoms of a refrigerant leak besides ac blowing warm air include iced coils, iced refrigerant line, hissing sounds, or higher electric bills without explanation. Refrigerant leaks must be repaired by a licensed HVAC technician, you should never try fixing refrigerant issues yourself. The sooner you call for professional help the better.

Contact LA Heating and Air For AC Repair

If you need air conditioner repair at your home give us a call today at 818-341-3406 to schedule service. Keep in mind the best way to prevent your AC from blowing warm is by scheduling routine maintenance for your system. Give us a call today or contact us online we are here to help you!

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