Does Turning the AC On and Off Cost More?

When summer heat sets in, homeowners across the country ask the same question: Should I turn the air conditioner off when I leave, or should I just leave it running all day? Does turning the AC on and off cost more?

It’s a debate that’s not just about dollars — it’s also about comfort, energy efficiency, and the lifespan of your HVAC system. While some believe turning the AC off and on wastes energy due to the startup process, others argue that letting it run nonstop is a bigger drain on your wallet.

In this guide, we’ll explore the facts behind AC usage patterns and reveal what experts say about energy savings, long-term system health, and optimal cooling practices.

How Air Conditioners Work

Understanding how air conditioning works helps clarify why certain myths persist. Generally speaking, an air conditioning system operates by:

• Drawing warm air from your home
• Passing that air over refrigerant-cooled coils
• Blowing cooled air back into the home while releasing heat outside

This cycle continues until your home reaches the thermostat’s set temperature.

Does Startup Use More Energy?

Many people assume that starting up an AC system requires a huge burst of power, but the energy used during startup is minor. AC units draw a slightly higher amount of power for a few seconds when turning on, but this is not enough to outweigh the energy saved by shutting the system off for hours at a time.

AC Efficiency Myths:

Myth: Turning your AC off and on wears it out faster 

Reality: That only applies if the unit short-cycles (turns on/off too frequently)

Myth: It takes more energy to cool a hot house later 

Reality: The energy to cool a home from 80°F to 72°F is similar whether it’s done gradually or all at once

Does Turning the AC On and Off Cost More?

This is the heart of the matter, and the answer depends on a few key variables. For most homes, turning it off when you’re away saves money.

Why Startup Costs Are Overestimated

According to Today’s Homeowner, the idea that an AC uses more energy turning on than staying on is false. The brief surge of electricity during startup is negligible compared to the power used over hours of continuous operation.

A well-maintained AC system should not short-cycle unless it’s improperly sized or has a malfunction. So turning it off for 4–8 hours — like during workdays or errands — reduces total energy use, even if it has to work a bit harder once you return.

When Turning It Off Saves Money

The energy you save depends on:

• Home size and layout: Larger homes take longer to cool back down
• Insulation quality: Well-insulated homes retain cool air longer
• Outdoor temps: Mild weather makes recovery easier

Short-Cycling Warning

Avoid manually turning your AC on and off multiple times an hour, as this can cause premature wear. If you frequently leave and return throughout the day, a smart thermostat is a much better option (more on that soon).

The Downsides of Leaving the AC Running All Day

If your air conditioner is cooling an empty house for hours, that’s not just inefficient — it can actually harm the system over time.

Here are the top risks of leaving your AC running 24/7:

• Wasted Energy: Cooling empty rooms adds unnecessary utility costs
• Increased Wear and Tear: Constant runtime strains the compressor, fan, and motor
• Shorter System Lifespan: More frequent repairs and replacements
• Environmental Impact: Higher energy use contributes to increased carbon emissions

The longer your AC runs, the more strain it endures — leading to higher repair bills and lower system efficiency over time.

Instead of running it all day, use a programmable thermostat to prep the home for your return. That way, it’s cool when you get back, without wasting hours of energy.

When It Makes Sense to Turn the AC Off

While it’s not always ideal to completely shut down your air conditioner, there are specific situations where doing so can save energy and money without sacrificing comfort.

Turning the AC off makes the most sense when:

You’re Leaving for an Extended Period:

• Vacations: If you’ll be gone for multiple days, shut off the AC or raise the temperature significantly
• Workdays: Out of the house for 6–8 hours? Turn it off or set the thermostat to 78–80°F
• Weekend Getaways: No one’s home = no need for continuous cooling

During Mild Overnight Weather:

If outdoor temperatures drop to the 60s or low 70s, consider opening windows instead of running your AC. This is especially effective in dry climates with good nighttime air circulation.

Pro Tip: Use a ceiling fan or box fan to circulate air for enhanced overnight comfort.

When It’s Better to Leave the AC On

Of course, there are times when shutting off your air conditioner could jeopardize comfort and safety.

Here are some of the situations when it’s better to let the AC run, even while you’re away:

Extreme Heat Conditions

In areas where temperatures exceed 90–100°F, your home can become dangerously hot. Letting the AC run at a higher setpoint (like 78°F) helps maintain a base level of coolness and prevents:

• Excessive heat buildup
• Increased recovery time (which demands more energy later)
• Humidity problems that could damage walls or furniture

If You Have Pets or Electronics at Home

Pets, such as dogs and cats, are sensitive to heat. Similarly, sensitive electronics (like servers or home office setups) may require a climate-controlled environment to operate safely.

Don’t risk their comfort or safety. Maintain a moderate indoor temperature using a thermostat setting or automation schedule.

Need expert help managing indoor temps?
Our air conditioning service experts can evaluate your setup and help you balance comfort with efficiency.

Programmable and Smart Thermostats

One of the best ways to avoid the “Does turning the AC on and off cost more?” dilemma entirely is to install a programmable or smart thermostat. These devices automatically adjust your home’s temperature based on schedules, habits, and even weather forecasts.

Here are some of the benefits of upgrading:

Types of Thermostats:

• Programmable: Set different temps for morning, work hours, evening, and weekends
• Smart: Adjust automatically based on patterns or motion sensors
• Wi-Fi Enabled: Control your home’s climate remotely through apps

Why They Help:

• Energy Savings: Only run the AC when it’s truly needed
• Comfort: Pre-cool the home before arrival, reduce temperature during sleep
• Convenience: Set it and forget it — no more daily manual changes

Factors That Influence AC Efficiency

Whether you’re turning the AC on and off or leaving it on, overall system efficiency plays a significant role in energy consumption and home comfort. Even the most strategic usage won’t help much if your AC is struggling due to hidden issues.

Here are some of the common culprits that can reduce HVAC efficiency:

Dirty Filters

Clogged filters cause your system to work harder, pushing cool air, and increase energy use, straining the blower motor. Replace filters every 1–3 months, especially during summer.

Blocked or Leaky Ducts

Air leaks in your ductwork can waste up to 30% of conditioned air. Sealing ducts or investing in a zoning system can help redirect airflow where it’s needed most.

Poor Insulation or Seals

Drafty windows, thin insulation, and worn-out weather stripping allow hot air in and cool air out. This leads to longer runtimes and higher energy bills.

Aging AC Components

Older systems tend to lose efficiency over time, particularly when regular maintenance is neglected. If your AC is more than 10–15 years old, it might be time for an energy audit or system upgrade.

Tips to Reduce AC Costs Without Sacrificing Comfort

Want to save money on cooling without sweating it out? Here are smart, simple ways to reduce your AC usage while staying comfortable.

Smart Cooling Strategies:

• Use Ceiling or Box Fans: Fans create a wind chill effect, making you feel cooler even at higher thermostat settings
• Close Blinds During the Day: Prevent heat from entering through sun-exposed windows
• Weather-Stripping & Caulking: Seal up leaks around doors and windows
• Set Thermostat to 78°F (when home): This balances comfort and efficiency
• Schedule Preventive Maintenance: A tune-up can boost system performance by 10–15%

Bonus Tip:

Invest in a smart thermostat and set it to raise temps during your work hours, then lower it 30 minutes before you return. It’s the best of both worlds: comfort and cost savings.

Need help with upgrades or a tune-up? Contact our air conditioning service professionals to schedule a personalized inspection.

Should You Leave It On or Turn It Off?

Turning the AC on and off vs leaving it on… what’s the final verdict?

The Short Answer:

Turning your AC off when you’re not home saves money — as long as it’s not for just a few minutes or in extreme heat.

The Better Solution:

Use a smart or programmable thermostat to automate AC use. This gives you the control to:

• Avoid unnecessary cooling
• Prepare your home for your return
• Extend the life of your HVAC system

By combining strategic behavior with the right technology and routine maintenance, you can keep your home cool and your energy bills low.

Frequently Asked Questions

To wrap up, here are answers to some of the most common questions homeowners have about air conditioner usage, energy costs, and best practices.

Is it bad for the AC to be turned on and off frequently?

Yes, if it happens too often in short periods.

This is known as short-cycling and can cause wear and tear on your AC compressor. But turning your system off for several hours — like when you’re away for work or vacation — is perfectly fine and often encouraged for energy savings.

What’s the ideal thermostat setting when away from home?

Experts recommend setting the thermostat between 78°F–82°F when you’re away during warm weather.

This reduces energy use while still keeping your home cool and comfortable. Smart thermostats can automatically make these adjustments for you.

How long does it take to cool a house after the AC has been off?

It depends on your home’s insulation, size, and outdoor temperature, but most homes can cool down by 5–10°F within 30–60 minutes with a properly functioning AC.

Programmable thermostats can pre-cool your home before you return, avoiding discomfort when you first step inside.

Does turning the AC off completely save more than setting it higher?

In most cases, yes. Turning it off entirely prevents any energy use, while setting it higher still requires periodic cycling.

However, if you live in an area with extreme heat or poor insulation, a higher temp may be more efficient than a full shutdown.

Will a smart thermostat really make a difference?

Absolutely. Smart thermostats help reduce waste, optimize efficiency, and maintain comfort — all without constant manual adjustments. They’re one of the most effective tools to reduce HVAC-related energy bills.

Find Your Cooling Balance

Whether to turn your AC off or leave it running depends on your habits, home insulation, local climate, and equipment. But for most homeowners, turning it off during long absences and using a smart thermostat offers the best energy-saving solution.

Now that we’ve answered the question, “Does turning the AC on and off cost more?”, contact the HVAC specialists at ABC Plumbing, Sewer, Heating, Cooling, and Electric for expert guidance and local support. A technician is standing by to evaluate your system and upgrade your home’s energy efficiency.