June in DuPage County hits different. One week you’re in a sweater, and then suddenly it’s 91°F and your AC is running flat-out while your electric bill quietly stages a coup.
We’re a pressure washing company — not HVAC techs — but we know a thing or two about exterior maintenance. And the number of homes we clean where the AC condenser is caked in cottonwood, dirt, and debris? Startling.
Here’s the short version of what summer actually costs when your cooling system is fighting against you.
The Thermostat Setting Nobody Gets Right
Most homeowners set their thermostat to a target temperature and walk away. That’s not wrong, but it’s not efficient either.
The Department of Energy’s recommendation: 78°F when you’re home, 85°F when you’re not. Every degree lower than 78°F adds roughly 3% to your cooling costs. If you’re keeping it at 70°F all summer, you’re paying a premium for comfort you may not even notice.
Programmable and smart thermostats handle this automatically. If you don’t have one yet, a basic programmable model runs $25–40. The payback period is usually a single billing cycle.
What to set:
Home, awake: 78°F
Away (work hours): 85°F
Sleeping: 82°F (ceiling fan bridges the gap)
Window Unit vs. Central AC: The Real Tradeoff
Central AC wins on comfort. Window units win on cost — if you’re using them right.
The mistake most homeowners make: running a window unit in an open-plan space it wasn’t sized for, then wondering why the room never cools down. Window units are zoned cooling. They work best in a closed room they can actually manage.
A quick size guide for window ACs:
150–250 sq ft: 5,000–6,000 BTU
250–350 sq ft: 7,000–8,000 BTU
350–550 sq ft: 9,500–10,500 BTU
Undersized: runs constantly, never catches up. Oversized: short-cycles, leaves the room humid. Get the right BTU and a window unit can cool a bedroom for pennies a night.
The Exterior Problem No One Talks About
Your outdoor condenser unit needs airflow to do its job. When it’s buried in cottonwood, dirty, or blocked by overgrown shrubs — efficiency drops. The system runs longer, works harder, and wears out faster.
Basic exterior maintenance for your AC:
Clear a 2-foot radius around the condenser
Rinse the coils with a garden hose (low pressure, top-down) once a season
Replace air filters every 60–90 days, more if you have pets
Keep nearby dryer vents clear — lint and heat near the unit is a bad combo
When to Call a Tech (Don’t Guess)
Some things you can DIY. Some things you absolutely should not touch. Here’s the line:
Call a licensed HVAC technician when you notice:
The system is blowing room-temperature air after 15+ minutes
Ice on the refrigerant lines or the unit itself
Unusual sounds — grinding, squealing, banging
A sudden unexplained spike in your electric bill
Refrigerant smells (sweet, chemical odor)
A tune-up runs $80–150. A compressor replacement runs $1,200–2,800. The math isn’t complicated.
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