Should I turn my AC off when I'm not home? Experts weigh in on Texas heat

Texas is finally creeping into triple-digit temperatures after a relatively mild start to summer and an unusually warm spring.

Just last month, cities along the Texas-Mexico border recorded some of the hottest temperatures on Earth, hitting 113 degrees as a heat dome pushed thermometers to extreme highs.

With what's shaping up to be one of the hottest summers on record, it's no surprise that many Texans are already desperate for relief.

As the heat intensifies, one question looms for many households: Is it better to leave the air conditioning running or turn it off when you're not home? What will keep the house cooler? What will be better for the electric bill?

Opinions may vary among homeowners, but experts are clear.

Should you turn off your AC or leave it on when you're away from home?

When your air conditioner is off for extended periods, your home can become humid — especially during peak summer. That trapped moisture can lead to mold and mildew growth, warp wood, damage paper goods and make the space feel muggy and uncomfortable, according to McGowan's Heating and Conditioning.

It also means that when you eventually turn the AC back on, it will have to work overtime to cool the home back down, potentially spiking your energy bill, the HVAC company wrote.

Worse, frequently switching the unit on and off can put added strain on key components, like the compressor, shortening the system’s lifespan and leading to more frequent — and expensive— repairs.

Instead of turning it off completely, experts recommend setting your thermostat a bit warmer than usual — between 75 and 85 degrees — while you're away. This keeps your home from becoming overly humid and prevents your AC from overworking when you return, all while saving energy. It strikes a balance between efficiency and comfort, helping you avoid both high bills and long-term damage to your system.

Even a 1-degree difference increases AC efficiency by 1 to 5%, while those who increase their thermostats by 7 to 10 degrees for eight hours a day can reduce their costs by around 10%, according to McGowan's.

What about during a trip or vacation?

If you’re leaving the house for just a day or two, the advice is the same: turn the thermostat up, but don’t turn it off — especially in Texas heat.

The U.S. Department of Energy notes that maintaining a higher indoor temperature while you’re away can actually slow the flow of heat into your home, helping reduce energy use and lower costs.

When you return, resist the urge to crank the thermostat way down. Dropping it to a very low setting won’t cool your home any faster. Instead, it forces your system to run longer, driving up your energy bill and increasing the risk of freezing your AC unit.

Should I turn my air conditioner off at night and open the windows?

If you don't have central air conditioning, opening windows and turning on fans is a good alternative. However, it might be counterproductive if you use AC during the day.

Depending on humidity, leaving windows open can let in hot, moist air. In addition to being uncomfortable, this air can be absorbed by carpet and furniture, increasing the possibility of mildew.

Plus, nighttime temperatures are warming faster than daytime temperatures, meaning you may not get the relief you expected. It might not be worth opening windows at night if you're trying to conserve energy and avoid running the AC, as temperatures may remain uncomfortably high even after sunset.

Opening windows could also let out the cooler air that was circulating throughout the day, which defeats the purpose of trying to keep the interior cool. Instead, it might be more effective to set the thermostat a few degrees higher during the night, rather than allowing the cool air to escape.

Should I spray my outside unit with water?

Gently spraying it with a hose can help keep things moving.

Over time, dust, grass and debris build up on the condenser coils, making the unit less efficient. Spraying it down with a garden hose (with the power off) can improve airflow and cooling performance.

Avoid using high-pressure nozzles and never spray the indoor components.

Best ways to keep your home cool and save energy

• Replace your air filter regularly: A dirty filter reduces airflow and makes your system work harder. Check it monthly during summer.
• Use a programmable or smart thermostat: Set higher temps when you're away or asleep to save energy without sacrificing comfort.
• Close blinds and curtains during the day: Blocking sunlight helps reduce indoor heat, especially on south- and west-facing windows.
• Seal windows and doors: Prevent cool air from escaping by sealing any leaks with caulk or weather stripping.
• Limit heat-generating activities: Use the oven, stove or dryer during cooler times of day — or opt for an air fryer, microwave, toaster oven or grill.
• Don't leave ceiling fans on: They help rooms feel cooler, but they don’t lower actual temperature — so turn them off when leaving the room.