There’s nothing worse than coming inside on a hot summer day and being welcomed by your AC blowing warm air instead of cooling off your home.
We’re here to help you troubleshoot this problem with eight of the most common parts of your HVAC system that could be causing it—and what to do about them. This guide will walk you through how to check your AC unit, how to take care of small fixes, why it’s important to stay on top of regular maintenance, and when it’s time to call in the pros.
1. Thermostat
This may seem too obvious and too simple, but if your AC is blowing warm air, always start by double-checking your thermostat settings before launching a full inspection on your unit. Make sure it’s set to “cool” and not “heat” or “fan.”
Verify that it’s set lower than the current room temperature. See if the batteries are dead and change them if necessary.
2. Air Filter
Another thing you should check early on is your air filter. Clogged or dirty air filters restrict airflow through your system, forcing your unit to work harder. Beyond making your AC unit blow warm air, this additional effort reduces energy efficiency, increases your utility bill, and damages other components if it’s not addressed promptly.
Filters should be replaced about every three months, so make a note on your calendar to keep your system running efficiently. Remove your old filter from the compartment and slide in the new one of the same size and type, carefully following any instructions on the packaging or unit itself to ensure it’s oriented and installed correctly.
4. Outdoor Unit
It’s always a good idea to step outside and ensure everything’s in order with your outdoor unit. Clear away any debris, dirt, or other obstructions around the unit to improve airflow and keep the internal components clean. Carefully inspect your unit, paying special attention to the condenser coil—if it’s dirty or blocked, that may be the cause of your AC blowing warm air.
Ensure that the fan blades are spinning and you can hear a consistent hum, which indicates that the air is flowing properly. If your fan isn’t running or you hear strange noises, double-check all power connections and confirm that you have clean filters. If that doesn’t help, it’s time to call in the pros.
5. Refrigerant
Refrigerant absorbs heat from the air inside your home and releases it outside, ensuring your space remains comfortable. The efficiency of your AC system heavily depends on sufficient refrigerant levels, as low levels from leaks can hinder the cooling process and increase energy consumption.
In addition to your AC blowing warm air, common signs of refrigerant leaks include ice buildup on the evaporator coils, hissing noises, or high energy bills. The gases and chemicals released by refrigerant leaks can be dangerous, so if you suspect a refrigerant leak, turn off your system and contact your HVAC team immediately.
6. Evaporator Coils
If your AC is blowing warm air, there may be an issue with your evaporator coils. Dirty coils have to work harder to function properly, which can cause them to freeze over and malfunction even more. Poor airflow through your system can also cause coils to freeze.
Warm air, weak airflow, ice on the coils or your unit, strange noises, refrigerant leaks, and your unit turning on and off all indicate that your evaporator coils need some attention. Change your filters and remove any debris that could be restricting airflow, and call an HVAC professional if you still have problems.
7. Ductwork
Leaky ductwork is one of the most common culprits when your AC is blowing warm air. Cold air may be getting lost through leaks or blocked by dirt or debris buildup in your ducts. Besides warm air, uneven cooling and increased energy bills can also indicate that something is wrong with your ducts.
If you notice any of these signs and can’t identify any other problems, call an HVAC professional to schedule a duct inspection, cleaning, and repair.
8. System Age & Maintenance History
When was the last time you had a tune-up done on your system? How long have you had your current unit? Aging or neglected HVAC systems may not run as efficiently due to dirty or failing parts, unaddressed inefficiencies, or other issues. Your unit needs professional maintenance at least once a year, so be sure to schedule a check-up if you’re overdue.
If you’ve stayed on top of maintenance and can’t pinpoint any other reasons why your AC is blowing warm air, it may simply be wearing out. Ask your HVAC techs to take a look and advise you on repairs or purchasing a new unit. As a general rule, if repairs are going to cost more than 25% of the cost of a new unit, it’s best to invest in the newer, more efficient model.
Keep It Cool with Bell Cow
You deserve to be safe, cool, and comfortable in your own home, and we’re here to make sure that happens. All of your HVAC needs, from routine maintenance to repairs and replacements, will be met with care and precision when you choose Bell Cow. You won’t find a more skilled and professional team. Schedule your HVAC tune-up and bookmark our contact info so you can stay on top of your AC care this summer.