The Best Thermostat Settings for Summer Efficiency on Long Island

Every summer we get calls from homeowners who are shocked by their first real PSEG bill of the season. And nine times out of ten, the problem isn't a broken air conditioner. It's a combination of bad thermostat habits and a system that hasn't had a proper AC tuneup in years.

Getting your thermostat settings right is one of the easiest ways to cut your cooling costs without spending a dime. But those settings only work if your air conditioning system is actually running efficiently. Let's talk about both.

The 78-Degree Rule and Why It Works

The Department of Energy recommends 78°F when you're home, and honestly, that number holds up. Most people push back on it at first because it sounds warm. But if your central air system is sized correctly and your home has decent insulation, 78 feels a lot more comfortable than you'd think. This is especially true if your HVAC system has had a recent tune-up and the air filter is clean.

The real savings come from the gap between the outdoor temperature and your thermostat setting. Every degree you lower your thermostat below 78 adds roughly 3% to your cooling costs. So if you're running at 72 all summer, you're paying about 18% more than you need to.

That doesn't mean you have to live at 78 if you genuinely can't stand it. But knowing the math helps you make a smarter call about where to land.

What to Set When You're Away

This is where most people leave money on the table. If you're at work all day with the AC cranked to 74, you're cooling an empty house for eight or nine hours straight.

When you leave for more than an hour, bump it up to 85 or turn the system off entirely. Your air conditioner won't have to work as hard as you think to bring it back down when you get home. On Long Island, most properly sized systems can pull a house from 85 to 75 in about 30 to 45 minutes.

The common myth is that it takes "more energy" to cool a house back down than to maintain a constant temperature. That's not true. The longer your AC runs at a low setpoint, the more energy it uses, period. Letting the house warm up while you're gone and cooling it back down when you return uses less energy and can save you money every billing cycle.

A programmable or smart thermostat makes this automatic. Set a schedule once and forget it. Wake up at 76, bump to 85 when you leave at 8, pre-cool to 76 before you get home at 5, and ease up to 78 at bedtime.

Night Settings and the Fan Switch

Sleep quality matters, and most people sleep better in cooler rooms. The sweet spot for most is somewhere between 68 and 72 at night.

If you're running your AC at 68 overnight, that's a big ask for the system during July and August when overnight lows on Long Island barely drop below 75. Your compressor will run almost constantly. A better approach: set the thermostat to 72 at night and use a ceiling fan. Moving air makes a room feel about 4 degrees cooler without using anywhere near the energy your air conditioner does.

Your thermostat also has a fan setting that matters more than most people realize. Keep it on Auto. Running the fan continuously sounds like it would help, but when the AC cycles off, the evaporator coil is wet with condensation. If the fan keeps blowing, it re-evaporates that moisture right back into your house. In our humid summers, that means your home feels muggy even though the temperature reads fine.

Why Your Settings Won't Matter Without an AC Tune-Up

Here's the thing most homeowners miss. You can dial in perfect thermostat settings and still get crushed by high energy bills if your air conditioning system hasn't had routine maintenance. An annual AC tune-up is what keeps your system running efficiently through the cooling season.

During a tune-up, an HVAC technician will inspect the components that directly affect how well your thermostat settings translate to actual comfort. That includes checking refrigerant levels, cleaning the evaporator and condenser coils, inspecting the blower motor, testing the capacitor, clearing the condensate drain line, and replacing filters.

A dirty condenser coil alone can reduce your system efficiency by 30%. Low refrigerant charge means your air conditioner runs longer to hit the same temperature. A failing capacitor can cause your compressor to short cycle, which wastes energy and wears out parts prematurely. These are the kind of issues a tune-up catches before they become costly repairs.

If it's been more than a year since your last AC tune-up, that's worth scheduling before summer hits full stride. Most HVAC contractors recommend getting it done annually, ideally in early spring before the cooling season starts.

What a Good AC Tune-Up Should Include

Not all tune-ups are created equal. A proper air conditioner tune-up should include inspection of the indoor and outdoor unit, checking the refrigerant charge, cleaning both the evaporator coil and condenser coil, testing electrical connections and amperage, lubricating moving parts, clearing the condensate drain to prevent clogs and water damage, inspecting ductwork for leaks, and verifying thermostat calibration.

That last one ties everything together. If your thermostat isn't reading the room temperature accurately, all the careful settings in the world won't keep your home comfortable. A good technician will check the calibration as part of the tune-up and let you know if the thermostat itself needs attention.

On Long Island, you're typically looking at $99 to $189 for a standard AC tune-up. That's a pretty small investment when you consider it can extend the life of your system by years and prevent a mid-summer breakdown on the hottest day of the year. Some heating and cooling companies offer maintenance plans that include an annual AC tune-up plus priority scheduling, which is worth considering if your system is getting older.

When Your Settings and Tune-Up Still Aren't Enough

If you've dialed in your thermostat and your heating and cooling system has had regular maintenance but your energy bills are still high, a few things to check:

Your air filter. A dirty filter restricts airflow and makes your air conditioner work harder for the same result. Replace filters every one to two months during the summer months. If you haven't swapped yours recently, that's your first move.

Your ductwork. Leaky ducts in an unconditioned attic can waste 20-30% of your cooled air before it reaches your living space. That's common in a lot of Suffolk County homes built in the 60s and 70s. A good HVAC technician can inspect your ductwork during an annual tune-up and flag any problems.

Your system's age and overall lifespan. An AC unit that's 15 or 20 years old just isn't going to perform like it did when it was new. Even with regular AC tune-ups, every air conditioner eventually reaches a point where repair costs start outweighing replacement. The average life expectancy of a central air conditioner on Long Island is 15 to 20 years, and preventative maintenance can help you get to the upper end of that range. If you're noticing higher bills every year, it might be time to evaluate whether a replacement makes sense.

Bottom Line

The best thermostat settings for summer aren't complicated. 78 when you're home, 85 when you're away, 72 at night with a fan running. Keep the fan on Auto. Use a schedule instead of guessing.

But those settings only deliver real savings when your air conditioning system is in good shape. Regular AC tune-ups help keep your system running smoothly and efficiently, catch small problems before they turn into expensive repairs, and improve indoor air quality along the way. Getting an AC tune-up annually is one of the simplest things you can do to protect your investment and keep energy efficiency where it should be.

If your system is struggling to keep up even with the right settings, or if it's been a while since your last tune-up, give us a call at 631-209-7090 or schedule a service call online. We'll inspect your outdoor unit and indoor components, check your refrigerant, clean your coils, and let you know honestly what shape your system is in. No pressure, no upsell. Just an honest answer from an HVAC contractor who'd rather keep your air conditioner in top shape than sell you a new one.