If your AC isn’t cooling properly during a heatwave, clogged filters, low refrigerant, or poor insulation could be the cause. Regular maintenance, proper airflow, and sealing leaks can help your system run efficiently in extreme heat.
Many homeowners assume their AC unit is failing, but the issue is often caused by overworked systems, poor airflow, or external heat factors. Understanding why your AC struggles in extreme heat can help you troubleshoot the problem, restore cooling efficiency, and prevent future issues.
Common Reasons Your AC Isn’t Cooling During a Heatwave
Your AC Is Struggling Against Extreme Outdoor Temperatures
During a heatwave, outdoor temperatures can exceed 90°F–100°F, making it harder for your AC to keep up with cooling demands. Most AC systems are designed to cool 15–20°F below outdoor temperatures, so if it’s 100°F outside, your AC may only be able to cool to 80°F indoors.
Dirty Air Filters Are Restricting Airflow
- A clogged air filter prevents proper airflow, making your AC work harder.
- Dirty filters cause weak airflow from vents, reducing cooling efficiency.
- Solution: Replace or clean air filters every 1–3 months to maintain performance.
Low Refrigerant Levels Reduce Cooling Power
- Refrigerant is essential for absorbing heat and cooling your home.
- A leak or low refrigerant levels can cause warm air to blow from vents.
- Solution: Call an HVAC technician to check for leaks and recharge refrigerant.
The AC Unit Is Too Small for Your Home
- An undersized AC system won’t be able to cool your home effectively.
- If your AC runs constantly but never reaches the set temperature, it may be too small.
- Solution: Upgrade to a properly sized AC unit for better efficiency.
Ductwork Leaks Are Reducing Efficiency
- Leaky ducts allow cool air to escape before reaching rooms.
- Common signs include uneven cooling, higher energy bills, and weak airflow.
- Solution: Have a professional inspect and seal duct leaks to improve airflow.
Your AC Condenser Is Dirty or Blocked
- The outdoor condenser unit needs proper airflow to release heat.
- Dirt, leaves, or debris can block airflow and cause overheating.
- Solution: Clean the condenser coils and keep the area around the unit clear.
Thermostat Issues Are Causing Improper Cooling
- If the thermostat is set incorrectly or malfunctioning, your AC won’t cool properly.
- Placement near heat sources like windows or electronics can affect readings.
- Solution: Ensure the thermostat is set to “Cool” mode and placed correctly.
Windows and Doors Are Letting Heat In
- Sunlight, open windows, and air leaks make it harder for your AC to cool efficiently.
- Poor insulation allows heat to enter your home and reduce cooling performance.
- Solution: Close curtains, seal air leaks, and improve insulation.
How to Help Your AC Cool More Effectively During a Heatwave
If your AC isn’t keeping up, try these quick fixes to improve cooling efficiency:
- Close blinds and curtains to block direct sunlight.
- Run ceiling fans counterclockwise to help circulate cool air.
- Avoid using heat-producing appliances (ovens, stoves) during peak heat hours.
- Ensure all vents are open and unblocked to allow proper airflow.
- Schedule AC maintenance before the peak summer season.
Final Thoughts
Your AC may struggle to cool properly during a heatwave due to high outdoor temperatures, clogged filters, low refrigerant, or airflow restrictions. Regular maintenance, proper insulation, and strategic cooling methods can help your AC perform better and keep your home comfortable even in extreme heat.
