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Why Your AC is Blowing Hot Air and How You Can Fix It


As the temperature rises in summer, you rely on your AC to keep you comfortable. You came home after a long day at work hoping to have a pleasant sleep, only for your AC to let you down in the scorching summer heat. Frustrating. Your AC blowing hot air in such a perilous time in an act of rebellion. What is the problem? It’s not always a serious problem that requires the visit of technicians. Sometimes, by just knowing the cause, you can get it fixed in a breeze.

Below are possible reasons why AC is blowing hot air and how to fix them.

Let’s proceed!

6 Reasons Why Your AC is Blowing Hot Air

1. Dirty   

A dirty AC unit or clogged air filter is a major cause of hot air blowing from your AC. To prevent this, ensure a free flow of air through the system by cleaning or replacing the air filter when it gets dirty. A dirty filter can disrupt function, block air passages, freeze the evaporator, and cause the AC to overwork, leading to other issues.

2. Refrigerant leak 

Your AC’s ability to cool the air is hanging on the refrigerant level. The refrigerant is what cools the air that’s sent to the room. If the level is low due to leaks caused by corrosion or wear-and-tear, your AC will start blowing hot air. When the refrigerant leaks out, it hinders the process, and frost may form on the evaporator coils while the air inside your home remains warm. Corrosion and wear and tear are the common cause of refrigerant leaks.

3. Faulty compressor 

If you switch on your unit, it uses a refrigerant to produce cold air that blows out of the vents. But if you switch it on and it is blowing hot air, the compressor in your unit is malfunctioning. If that is the case, the refrigerant won’t be able to turn from a gas to a liquid, which is necessary for cooling the air. So, it’s crucial to ensure that the refrigerant can flow smoothly through the system to guarantee that you get that refreshing blast of cold air. 

4. Condenser issues 

Your AC unit produces a lot of condensation while running, which is carried outside through the condensate line. However, the constant moisture can cause mold and algae buildup, leading to clogs that prevent proper humidity removal and result in hot air blowing into your home. 

5. Thermostat malfunction 

If your thermostat isn’t giving the correct reading, it can cause your AC to keep blowing hot air even in a hot room. For example, let’s say your thermostat is giving a low temperature even during the hot summer. The innocent AC since it is synced with the thermostat will try to warm the room further, sending hot air. Or it could be a simple error in your thermostat settings. For instance, some homeowners may have set their thermostat to the “fan” mode instead of “auto”. This causes the air to blow continuously, even when the AC isn’t in its cooling cycle, resulting in warm air blowing out of the unit.

6. The AC unit is too old 

Your AC blowing hot air and not functioning efficiently may imply it’s too old after 15 years of use. This is also a common cause, and it’s time to say goodbye. Contact your local HVAC company for a consultation on the best AC replacement options that suit your home and budget. Once you’ve made your decision, arrange for an upgrade and enjoy the cool air from your new AC.

How to Fix Your AC Blowing Hot Air 

1. Check and clean the air filter 

To troubleshoot hot air blowing from your AC, check and clean the air filter. If the evaporator coil is frozen, turn off the unit, change the air filter, and wait for the coil to thaw before turning the AC back on. If the coil continues to freeze, call an HVAC technician to diagnose and fix the issue, which could be a refrigerant leak or a faulty compressor.

2. Check for refrigerant leaks and recharge the system 

Refrigerants are dangerous, so refrain from attempting to fix refrigerant problems yourself if you are not a qualified technician. Schedule an annual AC tune-up to prevent refrigerant leaks. If you notice hot air blowing or other signs of a leak, contact your local HVAC company right away. Delaying repairs can worsen the situation, so act promptly.

3. Fix compressor issues 

Fixing compressors can be a difficult and expensive task, so many HVAC professionals opt to replace them instead. While you may be able to replace the compressor in smaller AC units yourself. It’s best to have a professional handle the job for larger units like central air, mini-split, and heat pumps. 

Once the compressor is fixed or replaced, the compressor should return to normal, and you should notice cold air blowing from your AC again if the compressor was the issue, causing hot air to blow.

4. Check the condenser and repair it if needed 

A clogged AC unit can cause it to blow hot air. If you notice your outdoor unit is clogged, turn off the power source and clean it by removing larger debris with gloves and rinsing smaller debris with a garden hose.

To maintain your AC unit, schedule a professional air conditioning tune-up and cleaning at the start of each cooling season. Ensure your HVAC company offers full indoor and outdoor coil cleanings as part of their standard tune-up. You should also inspect the outdoor unit occasionally and clean it if necessary.

5. Address thermostat malfunction 

Incorrect thermostat settings can cause AC issues. Double-check and set your thermostat to “cool,” the fan is on, and the temperature is lower than the outside. Set the blower fan in “auto” mode to run only during cooling cycles. Older dial-type thermostats may be calibrated improperly, leading to inaccurate readings and frequent adjustments. If so, have a professional replace or recalibrate it.

Preventive Measures to Avoid Future AC Issues

1. Regular maintenance of the AC system 

Scheduling HVAC maintenance twice a year, in the spring and fall, reduces the risk of unexpected breakdowns. No one wants to wake up in the middle of a passionate night to a broken AC.

2. Cleaning the outdoor unit 

Dirt, debris, and leaves can clog the outdoor unit, causing it to work harder to cool your home. Clean the unit regularly, especially before the summer months. Use a garden hose to rinse the unit thoroughly and remove any debris that may have accumulated.

3. Replacing the air filter 

The air filter helps to keep your indoor air clean and your AC unit running efficiently. Replace the filter every three months or as recommended by the manufacturer. A dirty filter can cause the AC unit to work harder, resulting in higher energy bills and potential damage to the unit.

Get help from an AC Expert in Benicia, CA

Are you tired of your AC blowing hot air and searching for reliable AC service in Benicia, CA? If your AC is blowing hot air, it may be as a result of various reasons, call an HVAC professional to help you discern the actual cause and fix it.

In precision air solutions, we perform AC routine inspections and tune-ups in the spring. We also offer an HVAC maintenance plan to keep your system running efficiently yearly and give you peace of mind. Reach out to us.