What to Do When Your AC Unit Is Not Cooling
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A functioning air conditioner during Carolina’s summer heat 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 Air, Heat & Plumbing is here to save the day by offering you troubleshooting advice and DIY tips to help.
Why Is My AC Running but Not Cooling?
If your AC is running but not cooling, the most common causes include a dirty air filter, thermostat issues, blocked vents, frozen evaporator coils, refrigerant problems, or a dirty outdoor condenser unit. Some of these issues can be resolved with simple DIY, while others require professional repair.
Before calling for service, follow the checklist and solutions below to see if you can resolve the issue quickly. If your AC still isn't cooling after these checks, it's time to schedule professional service.
AC Not Cooling: Troubleshooting Checklist
Symptom | Possible Cause | Safe DIY Check | Call a Pro? |
|---|---|---|---|
Weak airflow | Dirty filter | Replace filter | Yes, if airflow doesn't improve |
Warm air from vents | Thermostat setting | Verify "Cool" mode | Yes, if thermostat settings are correct |
Ice on indoor unit | Frozen evaporator coil | Turn system off and thaw | Yes, if thawing doesn’t resolve it |
Outdoor unit running but home stays hot | Refrigerant issue | Visual inspection only—do not attempt to fix | Yes, a professional is needed |
Certain rooms hotter than others | Closed vents or airflow issue | Open vents and check obstructions | Yes, if the issue continues |
AC System constantly runs | Dirty condenser or aging system | Clear debris around the outdoor unit | Yes, if cooling doesn't improve |
Common Reasons Your AC Is Not Cooling & Solutions
Below are six common issues and ways to fix an AC unit that's not cooling:
1. 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.
Solution: Replace the Air Filter
Swap your old filter out for a new one and see if the cool air returns.
2. Thermostat issues
If you feel your AC unit is not cooling, check your thermostat. Are your thermostat settings set to "cool" and your "fan" set on “auto”? You should also check battery settings or calibrate the thermostat to see if that solves the issue.
Solution: Check the Thermostat
Confirm the thermostat is set to "Cool" and that the temperature setting is below the current room temperature. “Fan” setting should always be set on “Auto” instead of “On”.
3. Blocked or closed vents
If you're like many homeowners, you may have a busy household. 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.
Solution: Inspect Vents
Make sure supply and return vents are open and unblocked by furniture, curtains, or household items, and air is flowing freely.
4. 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 trained professionals because of safety and environmental risks.
Solution: Call a Professional
Refrigerant is best handled by an AC professional with specialized training. Call us at 704-620-6252 or schedule online now.
5. 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.
Solution: Carefully Clear the Area
Sweep and clear the area around the outdoor AC unit and remove anything that could be blocking it.
6. Frozen evaporator coils
Sometimes, low refrigerant levels or restricted airflow can lead to frozen evaporator coils. Usually, you will see ice buildup on the refrigerant lines or indoor components.
Solution: Carefully Clear the Area
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, replace the air filter and turn the system back on. If the issue continues, call us!
When an AC Problem Becomes an Emergency
While many cooling problems can wait a day or two, some situations require immediate attention.
Contact a professional as soon as possible if:
Your AC stops working during extreme heat
Elderly family members, children, or pets are at risk
You smell burning or electrical odors
The system repeatedly trips breakers
Water is leaking around the indoor unit
Ice continues to return after thawing
Ignoring these warning signs can lead to more extensive repairs and additional damage. If you see any of these issues, call for emergency AC service right away.
Call Now or Monitor?
Situation | Monitor | Schedule Service Soon | Schedule Immediate Service |
|---|---|---|---|
Dirty filter | ✓ | ||
Closed vents | ✓ | ||
Frozen coil | ✓ | ||
Refrigerant leak | ✓ | ||
Electrical smell | ✓ | ||
No cooling during heat wave | ✓ |
Recap Checklist
Here's a recap checklist of how to fix an AC unit that's not cooling before calling one of our professionals for service.
First, turn off your AC system and:
Check and replace the air filter
Inspect thermostat settings and change batteries if necessary
Check and unblock vents
Clean debris away from the outdoor unit
Check the 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 cooling problems, replacements, or repairs!
