When temperatures climb during a summer heat wave, your air conditioner has to work much harder than it does on an average day. Longer run times, hotter outdoor temperatures, and increased cooling demand can expose weaknesses that may have gone unnoticed earlier in the season.
Some air conditioners simply struggle to keep up with extreme heat, while others may develop problems such as frozen evaporator coils, clogged filters, tripped breakers, or an overheating compressor.
Understanding the warning signs can help you determine whether your AC simply needs a little help during unusually hot weather or whether it is time to call an HVAC professional.
Why Heat Waves Are So Hard on Air-Conditioning Systems
During mild summer weather, an air conditioner may cycle on and off throughout the day. During a heat wave, however, the system may operate for much longer periods as it tries to remove heat from the home.
That extended workload can put additional stress on components such as the compressor, blower motor, electrical connections, and condenser fan.
Homes with poor insulation, air leaks, insufficient attic ventilation, aging HVAC equipment, or undersized air-conditioning systems may experience even greater difficulty maintaining comfortable indoor temperatures.
Here are some of the most common AC problems homeowners may encounter during exceptionally hot weather.
1. Frozen Evaporator Coils
It may seem strange that an air conditioner could freeze during a heat wave, but frozen evaporator coils are a relatively common cooling problem.
The evaporator coil is located inside the indoor portion of your HVAC system. Refrigerant flowing through the coil absorbs heat from the air passing over it.
If airflow becomes restricted, the coil can become too cold and condensation on the coil may eventually freeze.
Common causes include:
- Dirty air filters
- Blocked return vents
- Closed supply registers
- Dirty evaporator coils
- Blower motor problems
- Refrigerant issues
One warning sign is weak airflow from the vents even though the air conditioner is running. You may also notice ice on refrigerant lines or excessive water near the indoor unit after the ice begins melting.
If you notice ice, turning the thermostat lower will not fix the problem. Continuing to operate the system may make the condition worse.
Turn the cooling system off and contact an HVAC technician if the coil repeatedly freezes.
2. An Overheating AC Compressor
The compressor is one of the most important—and expensive—components of an air-conditioning system.
Located in the outdoor unit, the compressor circulates refrigerant through the HVAC system. During extremely hot weather, it may operate for extended periods with very little downtime.
Several conditions can increase the risk of overheating, including:
- Dirty condenser coils
- Restricted airflow around the outdoor unit
- Low refrigerant
- Electrical problems
- Failing condenser fans
- Aging equipment
- Extremely long operating cycles
Your outdoor condenser needs room to release the heat that was removed from inside your home. Grass, leaves, shrubs, debris, and dirt around the unit can restrict airflow and make heat removal more difficult.
Homeowners can help by keeping vegetation and debris away from the outdoor unit, but compressor and refrigerant problems should be diagnosed by a trained HVAC technician.
If the outdoor unit repeatedly shuts down, makes unusual noises, or fails to restart normally, professional service may be necessary.
3. A Clogged HVAC Filter
One of the simplest problems can also cause some of the biggest cooling issues during a heat wave.
Your HVAC filter collects dust and airborne particles before they enter the equipment. As the filter becomes clogged, less air can pass through the system.
Restricted airflow can lead to:
- Reduced cooling performance
- Longer AC run times
- Higher energy consumption
- Frozen evaporator coils
- Additional stress on the blower motor
- Uneven temperatures throughout the home
Filters may become dirty faster during the summer because the HVAC system operates more frequently.
Homes with pets, remodeling dust, wildfire smoke, or high indoor particle levels may need filter inspections more often.
Check your filter if your AC seems to be running continuously but airflow from the vents has become noticeably weaker.
Always use a filter that is appropriate for your specific HVAC system. A filter with excessive airflow resistance can create problems even when it is clean.
4. Tripped Circuit Breakers
An air conditioner requires a significant amount of electricity, particularly when the compressor starts.
If the system experiences an electrical problem or excessive load, the circuit breaker may trip to protect the electrical system.
If your AC suddenly stops running during a heat wave, checking the electrical panel may help identify whether a breaker has tripped.
A breaker that trips once does not necessarily indicate a major HVAC failure. However, a breaker that repeatedly trips should never simply be reset over and over.
Recurring breaker problems can indicate issues such as:
- Compressor problems
- Failing motors
- Damaged electrical components
- Loose wiring
- Short circuits
- Excessive electrical demand
Repeatedly resetting a breaker without identifying the cause may create a safety concern or contribute to additional equipment damage.
If the breaker trips again after being reset, contact an HVAC professional or qualified electrician.
5. Your AC Is Running but Cannot Keep Up
One of the most common complaints during a heat wave is:
“My air conditioner is running all day, but the house still isn’t cool enough.”
This does not automatically mean the air conditioner is broken.
When outdoor temperatures become significantly hotter than normal, an HVAC system may operate almost continuously. The system is also fighting heat entering the home through windows, walls, ceilings, doors, and air leaks.
However, an air conditioner that cannot maintain reasonable indoor temperatures may also have an underlying problem.
Possible causes include:
- Dirty air filters
- Low refrigerant
- Dirty condenser coils
- Leaking ductwork
- Poor attic insulation
- Inadequate airflow
- Aging equipment
- Improper AC sizing
If your home has always struggled to remain comfortable during hot weather, the existing system may also be improperly sized or the home may have insulation and air-sealing issues.
An HVAC technician can evaluate the entire cooling system rather than simply assuming that larger equipment is necessary.
6. Warm Air Coming From the Vents
If your AC is running but the vents are blowing warm or room-temperature air, several problems may be responsible.
Start by confirming that the thermostat is set to Cool and that the temperature is set below the current indoor temperature.
Next, check the air filter and make sure the outdoor condenser is operating.
If the system continues blowing warm air, possible causes include refrigerant problems, compressor issues, electrical failures, or frozen coils.
These problems require professional diagnosis.
7. Short Cycling
Short cycling occurs when an air conditioner repeatedly turns on and off without completing a normal cooling cycle.
During very hot weather, this pattern can make it difficult for the home to reach the desired temperature while increasing wear on the equipment.
Potential causes include:
- Dirty filters
- Frozen coils
- Thermostat problems
- Electrical issues
- Refrigerant problems
- Oversized equipment
- Overheating components
Frequent starts place additional stress on the compressor, so repeated short cycling should not be ignored.
How to Help Your AC During a Heat Wave
There are several simple things homeowners can do to reduce the workload on their cooling system.
Keep blinds or curtains closed on windows receiving direct afternoon sunlight. Avoid using heat-producing appliances such as ovens during the hottest parts of the day when possible.
You can also:
- Keep exterior doors and windows closed
- Check your HVAC filter
- Keep vents and return-air registers unobstructed
- Use ceiling fans to improve comfort
- Keep debris away from the outdoor condenser
- Avoid making dramatic thermostat changes
- Schedule professional maintenance if performance begins declining
Setting the thermostat significantly lower does not make an air conditioner cool the home faster. It simply tells the system to continue running until it reaches that temperature.
When Should You Call an HVAC Technician?
Some situations should be professionally evaluated rather than handled as DIY repairs.
Contact an HVAC company if you notice:
- Ice forming on the AC system
- Repeatedly tripped breakers
- Burning smells
- Loud or unusual noises
- Warm air from the vents
- Very weak airflow
- Water leaking around the indoor system
- An outdoor unit that will not operate
- Frequent short cycling
- An air conditioner that runs constantly without adequately cooling the home
A technician can inspect airflow, electrical components, refrigerant performance, coils, motors, thermostats, and other components to identify the actual cause of the problem.
Prevent AC Problems Before the Next Heat Wave
Many air-conditioning failures occur during the hottest days because that is when the system experiences its greatest workload.
Preventive maintenance before peak summer temperatures can help identify worn parts, dirty components, airflow restrictions, and other problems before they result in an unexpected breakdown.
Professional AC maintenance may include inspecting electrical connections, testing system operation, checking refrigerant performance, cleaning components, evaluating airflow, and verifying that the equipment is operating safely and efficiently.
Regular maintenance cannot prevent every repair, but it can reduce the likelihood that a minor issue turns into a major failure during the hottest part of summer.
Stay Comfortable During Seattle-Area Heat Waves
Summers throughout Bellevue and the greater Seattle area can place significant strain on air-conditioning systems, particularly during stretches of unusually hot weather.
Frozen coils, clogged filters, overheating compressors, electrical problems, and inadequate cooling are all signs that your system may need attention.
If your air conditioner is struggling to keep your home comfortable, HVAC Prime Systems can diagnose the problem and recommend the appropriate repair or cooling solution.
HVAC Prime Systems provides professional AC repair, maintenance, and installation services throughout Bellevue, Seattle, Kirkland, Redmond, Bothell, Everett and surrounding communities. Contact HVAC Prime Systems today to schedule air-conditioning service and keep your home comfortable through the summer heat.