Overworked System One of the most common reasons why your AC may struggle on hot days is that it's simply overworked. When the temperature soars, your AC has to work harder to maintain a comfortable indoor climate.
If your AC is running but not cooling, it could be due to a dirty air filter, incorrect thermostat settings, a malfunctioning thermostat, a refrigerant leak, dirty condenser coils, blocked vents or ducts, a faulty compressor, frozen evaporator coils, or electrical issues.
Depending on the system, an optimal time of 3 minutes is required before switching the system on. If the system is turned on without waiting for at least 3 minutes, the system can start with a pressure load. This pressure load prevents the system from cooling properly, which could affect the system in the long run.
When temperatures exceed 100 degrees Fahrenheit outside, setting your air conditioning (AC) to around 75-78 degrees Fahrenheit is generally considered efficient. Here are some reasons for this recommendation:
Not unusual. Most AC systems are only designed to cool your home to about 20 degrees less than the outside temperature - so unless you have a particularly good building envelope (ie lots of insulation and very little air leakage) your AC unit is likely fighting a loosing battle during the worst heat waves.
Your AC might not cool properly due to thermostat issues, an undersized unit, or extremely high outdoor temps—so check those first. Keep an eye on airflow—replace clogged filters every 3 months, and make sure vents and ducts aren't blocked for efficient cooling.
Cooling a house from 80 to 72 degrees is a common goal for many, especially during the peak of summer. On average, this process takes roughly two and a half to three and a half hours.
Just because the outdoor temperature is above 100, the Ideal temperature to set your AC unit to doesn't change — it's 78 degrees. Higher temperatures in the home are to be expected when the weather is hotter than usual, but your thermostat can still be set the same as if it were a lower temperature outside.
In general, 80 degrees is too hot for a house if people are inside. However, if people aren't home during the day or for vacation during the summer, an indoor temperature of 80 degrees can save energy until you return and lower the temperature.
Allowing your air conditioner to rest is an excellent way to extend its life and ensure it operates efficiently throughout the years. Air conditioners, like homeowners, require rest in order to recover and perform optimally.
Wear and Tear on the System
Turning your air conditioner completely off and then on forces the system to work harder. Each time the air conditioner starts, it experiences a surge of power, which can strain the components. Over time, this can lead to a breakdown or the need for premature repairs.
The New Regulations
Starting January 1, 2025, all new residential air conditioners and heat pumps must utilize A2L refrigerants. Older refrigerants like R-410, which are likely the refrigerant used by your current system, are being phased out.
Regularly cleaning vents and registers, ensuring they are not blocked by furniture or other objects, and checking and adjusting damper settings can help restore optimal airflow and improve your AC's cooling performance. Signs you may have blocked airflow: Low air pressure. Your system is blowing warm air.
It's recommended that you service your home air conditioning system at least once every year. The same goes for your heating system.
What should my AC be set at if it's 90 degrees outside? If the outdoor temperature is 90 degrees, it's recommended to set your thermostat between 75-78 degrees.
There are benefits to having your air conditioner set to “auto” and “on.” The benefits of the “auto” setting include higher efficiency, lower energy bills, better humidity control, less wear and tear on some components, and quieter running.
Best AC Temperature Settings While You Are Home
As you consider the most comfortable room temperature for your lifestyle and family, keep in mind that for each degree that you set your thermostat above 72 degrees, you can save up to 3% on your energy bill.
Blocked Airflow
If your AC doesn't receive enough air, circulating cool air will take much longer throughout your home. Blockages can develop at several points in your HVAC system that lead to reduced output and longer cooling times.
We recommend using these settings as a starting point and then adjusting to your comfort levels: 75° F during the day if people are home and at night when people are asleep. 80° F during the day if no one is home.
Typically, it takes about an hour for an average-sized air conditioning unit in typical conditions to lower room temperature by one degree Fahrenheit. But remember, 'average' doesn't mean 'always'. Like people, every AC has its personality – some are sprinters while others prefer marathons.
On very hot days, that means your home's AC equipment has to work extra hard. Not only is there more heat coming into the home via the sun through the windows, or hot air coming through leaky windows or doors, which it must remove, but the outdoor air is hotter.
How Often Do I Need to Change Out My Air Filter? Generally, most air filter manufacturers and HVAC companies recommend changing your air filter every 90 days, or 3 months. That can change based on where your home is located (ex. dusty, dry climates), if you have any pets, and the age of your system and equipment.
According to researcher Danny Parker from the Florida Solar Energy Center, who performed a two-year energy study, shading the unit provides “minuscule results at best” with efficiency being increased less than half a percent. While you may wish to cover your condenser since let's face it – they aren't very stylish!