As September rolls in, many homeowners in Great Falls know the drill: chilly mornings, warm afternoons, and cool evenings again. It’s what we call the “overlap season,” when your air conditioner and furnace may both get used within the same 24 hours. If you’re not careful, switching back and forth can lead to higher utility bills and extra wear on your equipment. The good news is that with a few simple adjustments, you can stay comfortable without breaking the bank.
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1. Don’t Chase the Thermostat
One of the biggest mistakes we see this time of year is constant thermostat changes. If you’re cranking the heat at sunrise, dropping it for AC by noon, and bumping it back up at night, you’re forcing your system to work harder than it should. Instead, choose a moderate temperature range, such as 68-70 in the morning and evening, and let it drift a few degrees warmer during the day. A smart thermostat can handle these adjustments automatically, which is especially helpful for Montana’s wide daily temperature swings.
Thinking about a smart thermostat? Read this to help you know if it’s right for you.
2. Use Nature to Your Advantage
Montana’s dry climate gives us big benefits during the overlap season. On sunny afternoons, let in natural warmth by opening blinds on south-facing windows. At night, when the air cools quickly, turn off your AC, open a few windows, and let the crisp breeze cool your home naturally. Just be mindful of wildfire smoke if it’s in the forecast since that is a common late-summer concern in our area.
3. Check Your Filters and Settings
We can’t say it enough: clean filters save money. A dirty furnace filter forces your system to work harder whether it’s heating or cooling. Also, make sure your thermostat is set to “Auto” rather than “On.” This way, the fan only runs when heating or cooling is actually happening, instead of constantly pulling electricity.

Air Filter Change Tips: Keep Your Great Falls HVAC Efficient
4. Layer Up Before You Power Up
Before you switch on the heat, try simple fixes like throwing on a sweatshirt or keeping a lightweight blanket nearby for the evenings. Likewise, a ceiling fan on low can circulate air and make a warm afternoon more tolerable before you flip on the AC.
5. Schedule a Pre-Season Tune-Up
Overlap season is also the perfect time to schedule furnace maintenance. By tackling it now, you’ll avoid the rush of emergency calls once the first real cold snap hits. Our technicians can spot small issues that might otherwise turn into breakdowns in December.
Why You Should Schedule Furnace Maintenance Before It Gets Cold
Stay Comfortable Without the Surprise Bill
The overlap season does not have to drain your wallet. With a few smart adjustments and a little planning ahead, you can stay comfortable while protecting your HVAC system. If you’d like help getting your furnace ready, give Halcro Heating and Cooling a call. We serve Great Falls and the surrounding 100-mile area, and we’d be glad to get your system tuned up before winter settles in.


