September brings with it many things. The appearance of yellow buses and orange leaves. Finding comfort in a hot cup of coffee instead of a cold can of soda. Half-on, half-off sweater days. Maybe even questions about your air conditioning (A/C)? If so, that’s something we can help with. 

Perhaps you’re wondering if you should turn off the A/C the first time the temperature dips below 75 degrees. Or should you hold out in case Mother Nature decides to “bless us” with a 90-degree heatwave in early October? This post holds the answer.

Is It Bad to Turn Off Your Air Conditioner? 

People often ask us if it is bad to turn your air conditioner on and off on a regular basis. The answer to this question depends on two things: external temperatures and how long you’re A/C will be off. 

As the weather gets cooler, there’s no reason to keep your A/C on standby if you don’t plan to use it. And, unless there’s a heat-wave of epic proportions, it’s very unlikely that you’ll need to crank up the A/C at any time during the next six months. 

However, let’s say the month of October haunts us with high temperatures and you need to scare away the heat and humidity. One thing you don’t want to do is to turn your A/C off when you leave for work and then back on when you return. This actually increases your energy use and costs because your air conditioner will have to start from scratch several times a week. 

A better approach would be to increase your target temperature by five to 10 degrees when you will be gone for more than eight hours. So, if you normally keep your temperature at 70 degrees, consider setting it to 75-80 degrees while you’re out. 

Should You Turn Off Your Air Conditioner Before Vacation?

In the heat of the summer, no. We suggest keeping with the previous advice of upping your temperature setting while you’re away. 

But as we move into shorter days, morning and evening temperatures tend to dip quickly—even if daytime temps reach into the 80s. So, around this time of year, whenever you’re leaving for more than a few days, it makes sense to shut down the A/C. Keeping your A/C turned on will cause the system to cycle on and off to maintain the temperature, using a lot of energy.

There’s no point in cooling an empty house, day after day. Instead, leave it off and enjoy some cost savings. Then when you return from your siesta, kick on the A/C if necessary. A/C systems are much more efficient and provide better dehumidification when running at full speed. 

Read: HVAC Tips: 8 Things to Do Before Heading Out on Vacation

Does It Cost More to Turn Off Your Air Conditioner?

Turning off the A/C isn’t always the best way to manage cooling costs. Time is the most important factor. When do you plan to turn your A/C back on? 

If it’s hours, or even a day or two, a good strategy is to boost your target temperature by five or 10 degrees. Why? Turning your A/C on and off is more expensive than just keeping the system on. 

But if you won’t need your A/C for an extended period of time—like a late summer cold snap before Indian Summer—just turn it off. You’ll save money in the long run.

When Should I Shut Off My Air Conditioner?

The bottom line is that there are two main times to shut off your A/C at this time of year:

1. When you’ll be gone for along time.
2. When you’re pretty certain that the warmer weather is gone for good. If it’s been a few weeks since the daily high temperature has exceeded 75 degrees, chances are that you’re not going to be turning on the A/C anytime soon.

Cool Tips to Help You Warm Up to the Changing Seasons

Based on the chill in the air each morning, it’s clear that the heating season is coming. Are you ready? Use our fall furnace maintenance checklist to get prepared.

Looking for a furnace tune-up? We offer a $99 cleaning maintenance and safety inspection.