How Heatwaves Impact Your AC and What to Do About It

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Gina Napsin
Date
June 06, 2025
Theme
Heating and Cooling
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Heatwaves are becoming increasingly common and intense, placing an immense burden on air conditioning systems. When temperatures soar beyond average levels, your AC unit is forced to work overtime to maintain indoor comfort. This excessive demand not only strains the unit but also significantly shortens its lifespan.
During a heatwave, the outdoor temperature often exceeds the design parameters of residential and even commercial HVAC systems. Most AC units are engineered to handle outdoor temperatures up to 95°F efficiently. When the temperature exceeds that, particularly during prolonged periods, the compressor and other internal components are pushed to their limits, risking breakdowns and operational inefficiencies.

Signs Your AC Is Struggling During Extreme Heat

When your air conditioner is overwhelmed by the heat, it begins to show signs of distress. These include:
  • Longer cooling cycles – The system takes longer to reach the set temperature.
  • Higher energy bills – The unit runs continuously, consuming more power.
  • Warm air from vents – Air isn’t as cold, even though the unit is running.
  • System short cycling – The AC frequently turns on and off due to overheating.
  • Unusual noises – Buzzing, humming, or rattling from overworked components.
Ignoring these warning signs could lead to complete system failure just when you need it the most.

How High Temperatures Affect AC Efficiency

Extreme heat not only forces your system to work harder, it also reduces its efficiency. The condenser coil, located in the outdoor unit, releases heat from inside your home to the outside air. During a heatwave, the ambient air is already hot, so the coil struggles to dissipate heat efficiently. This leads to:
  • Increased internal pressure within the system
  • Reduced cooling output
  • Higher refrigerant temperatures
  • More frequent tripping of safety switches
These heatwave effects on air conditioners contribute to a vicious cycle: the hotter it gets, the harder your AC works, and the less effective it becomes at cooling.

Common AC Problems During Heatwaves

Heatwaves amplify existing issues within an HVAC system. Common problems include:
1. Frozen Evaporator Coils
Though it may seem ironic, frozen coils can happen in extreme heat. When airflow is restricted - either due to dirty filters or a malfunctioning fan - the evaporator coil can freeze, reducing cooling power even further.
2. Refrigerant Leaks
The added pressure from high outdoor temperatures can stress refrigerant lines, potentially causing leaks. Low refrigerant levels decrease cooling performance and can damage the compressor.
3. Electrical Component Failures
Capacitors, contactors, and relays may fail under excessive heat, especially if the system is older or already showing signs of wear.
4. Clogged Air Filters
Air filters get dirtier faster during prolonged AC use. A clogged air filter reduces airflow and worsens indoor air quality, while also contributing to coil freezing and reduced efficiency.

How to Protect Your AC During a Heatwave

To ensure your air conditioning unit performs efficiently during extreme heat, you must take proactive steps:
1. Schedule Preventive Maintenance
Routine professional maintenance helps detect early signs of wear and tear. Annual HVAC inspections should include checking refrigerant levels, cleaning coils, inspecting ductwork, and testing electrical connections.
2. Change Air Filters Regularly
Check your filters every 30 days during the summer. Replace or clean them as needed to ensure unrestricted airflow and optimal cooling performance.
3. Use Programmable Thermostats
Install a smart or programmable thermostat to manage indoor temperatures effectively. Allow temperatures to rise slightly when no one is home to reduce the load on your AC.
4. Block Out Heat
Keep blinds, curtains, or shades closed during the hottest parts of the day. Consider using reflective window film or blackout curtains to reduce solar heat gain.
5. Avoid Heat-Generating Activities
During peak heat hours, refrain from using ovens, stoves, or dryers. These appliances add unnecessary heat, forcing your AC to work even harder.
6. Seal Air Leaks
Inspect windows, doors, and vents for drafts. Use weatherstripping or caulking to seal gaps and prevent cooled air from escaping.
7. Enhance Ventilation and Insulation
Ensure your home has adequate insulation, particularly in the attic and walls. Use fans strategically to circulate cool air and ventilate hot air from upper floors.

When to Call for Professional Help

If your AC unit still struggles despite these measures, it may be time to contact a licensed HVAC technician. Professional diagnostics can uncover deeper issues, such as:
  • Compressor failures
  • Electrical shorts
  • Refrigerant recharge needs
  • Motor replacements
Delaying repairs during a heatwave risks total system breakdown, leaving you vulnerable to dangerous indoor heat levels. To avoid costly damage and ensure long-term reliability, keep your HVAC system running with professional maintenance services provided by trusted experts.

Considering an Upgrade During Hot Seasons

If your air conditioner is over 10 years old, has frequent issues, or fails to cool effectively during heat waves, consider replacing it with a newer, energy-efficient model. Today’s HVAC systems come with higher SEER ratings, advanced humidity control, and smart features that offer:
  • Lower energy bills
  • Better performance during extreme weather
  • Reduced carbon footprint
  • Quieter operation
Inverter-driven compressors and variable-speed air handlers provide consistent comfort, even during heat waves, without constant cycling.

Energy Efficiency Tips to Reduce AC Load During Heatwaves

  • Install attic fans to expel hot air trapped in your roof space.
  • Landscape smartly by planting shade trees near south-facing windows and your outdoor AC unit.
  • Insulate ductwork, especially in attics or crawlspaces, to minimize energy loss.
  • Use ceiling fans to promote air movement and make the space feel cooler.
By combining these tips, you can optimize cooling without putting excessive strain on your HVAC system.

Health and Safety Considerations

It’s not just comfort that’s at stake - excessive indoor heat can be hazardous to your health, especially for young children, seniors, and individuals with respiratory or cardiovascular conditions. During heatwaves:
  • Stay hydrated
  • Limit physical activity during peak hours
  • Use fans with AC to circulate cool air
  • Check on elderly family or neighbors
Having a reliable and well-maintained air conditioning system is not just about convenience - it’s about safety. That’s why it’s important to count on trusted professionals like Home Alliance, who can ensure your HVAC system is ready to handle the heat when you need it most.

FAQs

  • Why does my AC run constantly during a heatwave?
During extreme heat, your AC must work longer to maintain the set temperature because the outdoor air is much hotter than usual. This prolonged runtime is the system’s effort to keep your home cool despite reduced efficiency.
  • Can high temperatures damage my AC unit?
Yes, excessive heat can cause internal pressure to rise, stressing key components like the compressor, capacitors, and refrigerant lines. Over time, this can lead to breakdowns and reduce the system’s lifespan.
  • How often should I change my air filter during the summer?
Check your air filter every 30 days during heavy AC use and replace it if it appears dirty. A clean filter ensures proper airflow and helps prevent coil freezing and energy waste.
  • Should I turn off my AC if it’s struggling to cool?
If your AC is blowing warm air or short-cycling, turning it off briefly can prevent further damage while you check for clogged filters or blocked vents. However, if issues persist, call a professional HVAC technician.
  • When is it time to replace my air conditioner?
If your unit is over 10 years old, needs frequent repairs, or struggles to cool during heat waves, it may be time for an upgrade. Newer models are more efficient, reliable, and better equipped to handle extreme weather.