Before You Turn On the Furnace: 10 Things Illinois Homeowners Should Check This Fall
Updated: Oct 4
The Home Inspector’s Early-Fall HVAC & Safety Check
The Midwest Homeowner Survival Guide: Summer → Fall — Part 4
The worst time to discover your furnace doesn’t work is the exact same morning everyone else in Illinois discovers theirs doesn’t work.
You know the morning.
Yesterday it was 78°.
Today it’s 39°.
Because Illinois weather apparently spins a wheel before going to bed.
You shuffle over to the thermostat, switch it from COOL to HEAT, hear a few mysterious noises from the basement...
...and nothing happens.
Or worse:
Something happens, but your furnace suddenly sounds like a washing machine full of lug nuts.
After spending the summer talking about roofs, drainage, foundations, gutters and everything Mother Nature has been throwing at the exterior of your house, Part 4 of the Midwest Homeowner Survival Guide: Summer → Fall is moving inside.
As a home inspector with Midwest Inspect, fall is when I start thinking about the systems we're about to depend on for the next several months.
Your furnace.
Your ventilation.
Your smoke alarms.
Your carbon monoxide alarms.
And a handful of other things that have been quietly sitting around all summer waiting for their seasonal comeback.
Before you need the furnace every day, give your house a little preseason inspection.
Here are 10 things Illinois homeowners should check before the first real cold snap arrives.
1. 🔥 Have the Furnace Serviced
Before Everyone Else Has the Same Idea
Your furnace may have been mostly relaxing since spring.
Soon, you're going to ask it to work around the clock for several months.
This is a good time to have a qualified HVAC professional inspect and service the system.
A professional may identify problems such as:
ignition issues
dirty components
deteriorated parts
blower problems
combustion concerns
venting issues
corrosion
abnormal operation
I've inspected plenty of furnaces that technically worked.
That's not the same thing as saying everything looked good.
And if your furnace has been making strange noises, producing unusual odors or behaving differently than it did last winter, don't wait for a 10° January night to investigate.
Midwest Inspector Translation:
Your furnace doesn't need a pep talk.
It may need maintenance.
2. 🌬 Check the Furnace Filter
Yes, That Thing You Were Going to Replace Three Months Ago
Few home-maintenance items are cheaper or easier than replacing an HVAC filter.
And somehow...
Filters still get forgotten.
I've pulled filters during inspections that looked less like air filters and more like something recovered from an archaeological excavation.
A severely dirty filter can restrict airflow and make your system work harder.
But there's another issue I encounter:
The wrong filter.
Too small.
Improperly installed.
Wrong orientation.
Or my personal favorite:
A filter that's technically in the general vicinity of where a filter should be.
Check the manufacturer's requirements for the proper size and type for your equipment, and make sure the airflow arrow is facing the correct direction.
Midwest Inspector Translation:
Your furnace shouldn't have to inhale through a dirty bath towel.
3. 🌡 Test the Thermostat Before You Actually Need Heat
Don't wait for the first freezing morning.
Turn the thermostat to heating mode while the weather is still comfortable enough that a problem isn't an emergency.
Listen.
Does the furnace start?
Does warm air eventually come from the registers?
Does it shut down when the thermostat reaches the set temperature?
If you have a programmable or smart thermostat, this is also a good time to check:
schedules
batteries, if applicable
temperature settings
heating modes
Because discovering at 6:15 AM that somebody accidentally programmed the house for 58° every weekday is a very specific kind of family argument.
4. 👂 Listen to Your Furnace
Houses Make Noise. Some Noises Deserve Attention.
Furnaces aren't silent.
You may hear:
clicking
airflow
burners operating
metal expanding and contracting
the blower starting and stopping
Those can be normal.
What gets my attention?
Grinding.
Screeching.
Banging.
Rattling.
Repeated clicking without ignition.
Or a blower motor that sounds like it's attempting to leave the furnace.
New or unusual noises are worth investigating.
Midwest Inspector Translation:
Your furnace should sound like mechanical equipment.
It should not sound like someone threw a handful of silverware into a garbage disposal.
5. 🔍 Look for Rust, Corrosion & Soot
Your Furnace Leaves Clues Too
You don't need to disassemble anything.
In fact, please don't.
But homeowners can visually check accessible areas around heating equipment.
Look for:
corrosion
rust
water staining
unusual deposits
soot or carbon-like staining
damaged venting
disconnected components
During inspections, soot or dark deposits around combustion equipment immediately get my attention because they can be associated with improper combustion or venting conditions.
Corrosion can also indicate that moisture or condensate has been somewhere it shouldn't.
These aren't conditions to diagnose with a YouTube video and a screwdriver.
If something doesn't look right, have it professionally evaluated.
Midwest Inspector Translation:
Black soot around combustion equipment isn't rustic farmhouse décor.
6. 💧 Check Condensate Drainage
Because Furnaces Can Have Water Problems Too
Depending on the HVAC equipment in your home, condensate may need to be properly collected and drained.
Check accessible condensate piping for:
leaks
disconnected lines
standing water
staining
damaged tubing
improper drainage
I've seen relatively small condensate problems damage:
furnace cabinets
flooring
drywall
nearby building materials
Water remains one of the most persistent enemies of a house.
Apparently it doesn't take winter off either.
7. 🏠 Look at the Combustion Venting
Exhaust Needs Somewhere Safe to Go
Fuel-burning appliances create combustion gases that need to be safely vented from the home.
Visible venting should not appear:
disconnected
badly corroded
damaged
improperly supported
separated at joints
I've encountered vent pipes during inspections with corrosion, questionable connections and evidence suggesting condensation or venting concerns.
That's not something to ignore.
A qualified professional should evaluate suspected combustion or venting defects.
Because unlike a squeaky floorboard, combustion safety isn't something we joke around with.
8. ☠️ Test Your Carbon Monoxide & Smoke Alarms
The Five-Minute Fall Maintenance Job That Actually Matters
This one is important.
As heating season begins, you're going to be using fuel-burning appliances more frequently.
Make sure your home has properly located, functioning:
Smoke alarms
and
Carbon monoxide alarms.
Test them.
Check their age.
Replace batteries where applicable.
And replace expired alarms according to manufacturer guidance and applicable requirements.
Carbon monoxide is colorless and odorless.
You cannot rely on smell to warn you.
Midwest Inspector Translation:
The little plastic thing on the ceiling isn't decoration.
Give it some attention.
9. 🧺 Check the Dryer Vent
Your Dryer Shouldn't Be Exhaling Into the House
While we're doing our indoor fall safety inspection, let's visit the laundry room.
Dryer vents are one of those things homeowners rarely think about until something goes wrong.
Look for:
crushed ducting
disconnected vent pipes
excessive lint
damaged exterior termination
improper materials
restricted airflow
The dryer should vent properly to the exterior.
Excessive lint accumulation can reduce dryer performance and create a fire concern.
If drying one load of towels now requires approximately the same amount of time as smoking a brisket...
It's worth investigating.
Midwest Inspector Translation:
Lint belongs in the lint trap.
Not packed inside six feet of dryer duct.
10. 🚿 Don't Forget Bathroom Exhaust Fans, Humidifiers & Ductwork
The Supporting Cast Matters Too
Your furnace gets all the attention.
But fall is a good time to look at the rest of the home's ventilation system.
Bathroom exhaust fans
Turn them on.
Do they work?
Are they actually moving air?
Bathroom fans help remove moisture from the home.
And ideally, they should exhaust to the exterior—not simply relocate shower humidity into an attic.
Whole-house humidifiers
If your HVAC system has a humidifier, fall is a good time to have it checked and prepared for heating season.
Too little winter humidity can be uncomfortable.
Too much can contribute to condensation and moisture problems.
Visible ductwork
Look for:
disconnected sections
damaged ducts
loose connections
visible gaps
significant corrosion
You don't need to crawl through your duct system wearing a headlamp.
That's my kind of poor life decision.
Just pay attention to what's visible and accessible.
BONUS: Your Nose Is Also an Inspection Tool
When you first turn on the furnace after months of inactivity, a brief dusty or "burning dust" odor can sometimes occur as accumulated dust heats up.
But persistent or unusual odors deserve attention.
Especially odors resembling:
burning electrical components
melting plastic
fuel or gas
persistent smoke
If something smells seriously wrong, don't shrug and say:
"Eh... furnaces probably smell like that."
Stop and investigate safely.
Your house has many ways of communicating.
Smell is one of them.
🏡 Buyers: HVAC Age Isn't the Whole Story
This is something I frequently explain during home inspections.
An older furnace isn't automatically a bad furnace.
And a newer furnace isn't automatically a good one.
Maintenance matters.
Installation matters.
Condition matters.
Performance matters.
I've inspected older systems that appeared well maintained.
I've also inspected relatively new equipment with installation defects, corrosion, poor filter arrangements or other concerns.
That's why a home inspection shouldn't simply say:
Furnace: 12 years old.
The useful question is:
What condition is it in today?
🏠 Sellers: This Is Easy Pre-Listing Homework
If you're thinking about selling your home this fall or winter, HVAC maintenance is one of those things worth addressing before the buyer's inspection.
Consider:
replacing the dirty filter
having overdue service completed
testing alarms
addressing known HVAC issues
clearing access around the furnace
gathering maintenance records
And please...
Clear the furnace closet.
I need to actually inspect the furnace.
If I open the utility closet and discover six winter coats, a vacuum cleaner, Christmas decorations, three Costco boxes and enough wrapping paper to supply Santa...
my inspection just became unnecessarily difficult.
Your furnace is mechanical equipment.
Not bonus closet space.
The First Cold Morning Is Coming
That's the thing about Illinois.
Fall can trick you.
We get beautiful 70° afternoons.
Windows open.
Perfect weather.
Football.
Bonfires.
Then one morning...
37°.
And suddenly several million people walk over to their thermostats at approximately the same time.
That's not when you want to discover:
the furnace won't ignite
the blower motor is failing
the thermostat isn't working
the venting is damaged
the filter hasn't been changed since the Bears' last winning streak
Okay...
Maybe don't use that as your maintenance interval.
Your 15-Minute Early-Fall HVAC Check
You don't need to be an HVAC technician to give your home a basic visual check.
Before heating season:
✓ Replace or inspect the furnace filter.
✓ Test the thermostat.
✓ Turn the heat on before you actually need it.
✓ Listen for unusual noises.
✓ Look for visible rust, corrosion or staining.
✓ Check accessible condensate lines.
✓ Visually inspect accessible venting.
✓ Test smoke and carbon monoxide alarms.
✓ Check the dryer vent.
✓ Test bathroom exhaust fans.
And if something doesn't look, sound or smell right?
Don't guess.
Have it evaluated by the appropriate qualified professional.
Final Thoughts
Fall home maintenance isn't about trying to become your own HVAC technician.
Please don't.
It's about catching obvious problems before they become emergency problems.
Because there's a significant difference between calling an HVAC company on a comfortable October afternoon and calling one at 6:30 AM when it's 14° outside and your family is wearing coats in the kitchen.
Your house has spent the summer battling:
☀️ Heat
💦 Humidity
⛈ Storms
🌧 Heavy rain
Now the next shift is coming.
❄️ Cold.
🌬 Wind.
🧊 Ice.
And several months of your furnace quietly carrying the team.
Give it a little attention before kickoff.
Because the worst time to discover your furnace has opinions...
is the exact same morning everyone else in Illinois discovers theirs does too.
Coming Next — Part 5: The Finale of The Midwest Homeowner Survival Guide: Summer → Fall
The First Freeze Is Coming: The Things I'd Do to My Own House Before Winter
We'll bring everything together with the final pre-winter checklist: exterior faucets, hoses, gutters, downspouts, sump systems, roof drainage, trees, exterior penetrations, weatherstripping, outdoor equipment, and the handful of small repairs that become considerably less enjoyable once you're doing them with frozen fingers.
Because in Illinois...
winter doesn't send a calendar invite.
Inspect Today. Protect Tomorrow.
— Sean Evans, CPI
Founder of Midwest Inspect
Serving Northern Illinois & Southern Wisconsin with professional home inspections designed to help buyers, sellers, and homeowners make informed decisions. Schedule your inspection today at MidwestInspect.com
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