Every September, I get some version of the same question from customers: “So… when do I actually switch over?”
I get it. Nobody wants to flip on the heat too early and waste money, but nobody wants to wake up shivering because they waited too long, either. After 40 years running Moon Air and crawling through more attics and crawlspaces across Maryland and Delaware than I can count, I’ve got a pretty reliable way I walk my own family through this decision every fall. I’m sharing it here so you can use the same approach.
My Quick Rule of Thumb
I tell people this: once your overnight lows are consistently sitting in the mid-60s or lower for about a week straight, it’s time to stop relying on your AC and get your heating system checked and ready. Here in Elkton, North East, Newark, Middletown, and the rest of our service area, that usually lands somewhere in late September through early-to-mid October, though I’ve seen it swing earlier or later depending on the year.
The key word is consistently. One cool night doesn’t mean anything. A full week of chilly mornings and evenings does.
Signs It’s Time to Make the Switch
Beyond just watching the thermometer, here’s what I tell my own customers to look out for:
Your AC is running but not really doing anything. If you’re setting your thermostat to cool and the house still feels clammy or just “off,” that’s usually a sign the outdoor temps have dropped enough that your AC isn’t operating efficiently anymore. AC systems are built to cool, not to dehumidify or fine-tune comfort in cooler weather.
You’re layering up indoors. If you’ve started keeping a sweatshirt on the back of the couch just for evenings, that’s your body telling you what the thermostat should already be handling.
Your furnace hasn’t been touched since last winter. This is the one people skip, and it’s the one that costs them. A furnace that sat idle all spring and summer can develop issues you won’t know about until the first genuinely cold night, usually a Friday at 9pm, in my experience.
Why I Push People to Get a Tune-Up Before They Actually Need It
Here’s the honest truth from someone who’s fielded thousands of emergency calls: the worst time to find out your furnace has a problem is the first time you turn it on for the season. That’s exactly when everyone else is calling us too, and exactly when a small, cheap fix can turn into “we need you tomorrow because it’s 38 degrees in my house.”
A pre-season tune-up does three things:
Catches small problems while they’re still small. A cracked heat exchanger, a failing igniter, or a dirty flame sensor are all things we can usually fix in one visit if we catch them early.
Keeps your system running efficiently. A furnace that’s been cleaned and checked burns fuel more efficiently, which shows up directly on your winter utility bill.
Gets you ahead of the rush. Once temperatures really drop, our schedule fills up fast with no-heat emergencies. Booking now means you get a convenient appointment time instead of an emergency one.
What I’d Do in Your Shoes
If your AC has been carrying you through summer and you can feel the season turning, don’t wait for the first cold snap to think about your furnace. Get it checked now, while it’s still convenient, not urgent.
That’s really the whole philosophy behind how we’ve run Moon Air since 1985: take care of the small stuff before it becomes the big stuff. It’s cheaper, it’s less stressful, and it means your system is actually ready when you need it, not just when you remember to think about it.
Frequently Asked Questions
How do I know if my house is ready to switch from AC to heat?
Once nighttime temperatures are consistently in the mid-60s or below for about a week, it’s a good time to stop cooling and get your furnace inspected and ready for the season.
How much does a furnace tune-up cost?
Costs vary depending on your system and what’s found during the inspection, but a routine tune-up is far less expensive than an emergency no-heat repair in the middle of winter. Call us at 410-384-6146 and we can give you a straight answer for your specific system.
What does a furnace tune-up include?
At minimum, it should include a check of your heat exchanger, igniter or pilot assembly, flame sensor, blower motor, filter, thermostat calibration, and a check for any carbon monoxide safety concerns.
Can I switch from AC to heat myself, or do I need a technician?
Switching your thermostat mode is simple and something any homeowner can do. But before you rely on your furnace for the season, it’s worth having a technician confirm the system itself is actually safe and ready to run, especially if it hasn’t been serviced since last year.
Ready to get your furnace checked before the cold really sets in? Give us a call at 410-384-6146, or ask about our maintenance plans, which cover both your fall furnace tune-up and your spring AC check-up in one visit. We’ve been keeping Maryland and Delaware families comfortable since 1985, and we’d love to make sure you’re ready for whatever this winter brings.
By Steve Moon, Owner, Moon Air