What to Do When Your AC Unit Is Not Cooling
July 15, 2025
A functioning air conditioner during a Carolina summer isn't a luxury—it's a necessity. So, when it suddenly stops working, dealing with a lack of cool air can be frustrating. But fear not, the team at Brothers is here to save the day by offering troubleshooting advice and DIY tips to help you keep a cool head this summer.
Common Reasons Your AC Is Not Cooling
Let's set the scene. You spent all day working outside in the sticky heat, and all you want to do is go home and chill on the couch. You enter your house, and the AC unit is running but not cooling—which means that the cool relief you sought is not there. Ugh! You immediately check on the AC and ask yourself, "Why is my AC running but not cooling?"
The answer could be one of many things.
Here's how to fix an AC unit that's not cooling…
Dirty air filters
Dirty air filters don't just look gross; they can severely disrupt your system's efficiency if you don't change them regularly (we recommend every three months). Filthy filters impede airflow and make your system work harder than it needs to. It's the most overlooked cause of poor AC function. Swap out for a fresh filter and see if the cool air returns!
Thermostat issues
If you feel your AC unit is not cooling, check your thermostat. Are your settings set to "cool" and not "fan"? You should also check battery settings or calibrate the thermostat to see if that solves the issue.
Blocked or closed vents
If you're like many homeowners, you may have a busy household with toddlers running around, teenagers lounging on couches, and dogs jumping on furniture. All this chaos sometimes leads to furniture getting moved or toys getting tossed aside. Be sure toys, chairs, or other objects are not blocking supply vents or return vents. Sometimes vents get bumped and may close when you're cleaning. Do a thorough check that nothing is blocking any of your vents and your air is flowing freely.
Refrigerant leaks
Sometimes, low refrigerant levels or leaks can result in your AC unit not cooling. If you notice your air conditioner is low on refrigerant, please call us. This type of fix is best left to professionals.
Dirty condenser
If the outside unit (condenser) is damaged or dirty, your cooling efficiency may be affected. Dirt, leaves, twigs, grass, and other debris can get stuck and block airflow. Sweep the outdoor unit and remove anything that could be blocking it.
Frozen evaporator coils
Sometimes, low refrigerant levels or restricted airflow can lead to frozen evaporator coils. If you notice your coils are frozen, turn off the air conditioner at the thermostat and set the fan to on. This will help thaw the ice. Once the ice has melted completely, inspect the coils and check for blockages. Replace the air filter and turn the system back on. If the issue continues, call us!
Recap Reminders!
OK, here's a recap of how to fix an AC unit that's not cooling before calling one of our professionals for service.
Turn off the AC if it's not cooling and…
- Check and replace the air filter
- Inspect thermostat settings and change batteries if necessary
- Check and unblock vents
- Clean debris away from outdoor unit
- Check circuit breaker for any tripping
- Inspect for ice on coils, thaw if necessary
If these DIY tricks don't fix your issues, please call our team of pros at 704-620-6252 to schedule service. As always, regular maintenance will help safeguard your system and may help prevent future problems or repairs!