What HVAC Service Costs in Plainfield & Naperville, IL (2026 Price Sheet)

Here is the full FortHouse Heating & Cooling price sheet. Service prices are flat. Repairs are a range because the failed part decides the number, and you get that number in writing after the diagnosis, before anyone picks up a wrench. Replacement prices are installed ranges; the free estimate turns the range into one written number for your house.

The diagnostic is the HVAC service call. A technician comes out, finds what actually failed, and hands you a written price for the fix. During regular hours that visit is $119 in Plainfield and in Naperville. We answer the phone 24 hours a day; the after-hours rate is quoted when you call (630) 318-6246, before anyone is dispatched.

A diagnosis takes a technician's time and a truck's fuel no matter what it's called. When a company advertises a free or very cheap service call, that cost doesn't disappear. It moves into the repair price, where it's harder to see. A stated fee is easier to compare: you know what the visit costs, and the repair quote that follows is just the repair.

The fee also buys you an exit. You get the written quote, and you decide. If the number is more than you want to spend on an old system, you've paid $119 to find that out, and you can put the quote next to a replacement estimate before deciding anything.

A furnace tune-up and an AC tune-up are each a flat $119. Each is a 21-point inspection that takes 60–90 minutes. The readings go on the invoice. If the paperwork just says "looks fine," nobody measured anything.

Book the furnace in early fall, before the first cold snap: furnace tune-up in Plainfield or furnace tune-up in Naperville. Book the AC in spring, before the first hot week.

Tune-ups advertised for $49 exist, and the math is simple. A real visit with combustion and refrigerant readings costs more than that to perform. At $49, the visit is a sales call with a wrench in hand, and the upsell is the actual product. At $119, the inspection is the product.

Most repairs run $150–$600 after the diagnostic. The part decides where in that range you land, and you see the number in writing before work starts.

On a furnace, an ignitor or a flame sensor sits at the low end and an inducer motor sits higher. On an AC, a capacitor or contactor is at the low end, and a fan motor or a refrigerant leak search runs higher. Details by city are on the AC repair in Plainfield and AC repair in Naperville pages.

Some failures don't belong in the repair column at all. A failed compressor on an AC or a cracked heat exchanger on a furnace usually means replacing the equipment is the better spend. The quote will say so instead of pricing a repair that doesn't make sense.

The shorthand we use is the 50% rule. If a repair costs more than roughly half of what a new unit would, or the unit's age times the repair cost tops $5,000, replacement usually wins on value.

An illustrative example: say a 16-year-old furnace needs a $450 repair. Sixteen times $450 is $7,200, which is past $5,000, so it's worth pricing a replacement before saying yes. The same $450 repair on a 6-year-old furnace is $2,700 on that math. Fix it.

Run the rule on each system separately. A dead furnace doesn't make a healthy AC a replacement candidate, and a crew already being in the basement isn't a reason to replace equipment with years of life left.

A furnace runs $5,000–$9,000 installed. The 80% AFUE tier is roughly $5,000–$7,000; the 95%+ AFUE tier is roughly $6,300–$9,000, including the new PVC venting it needs. See furnace installation in Plainfield or furnace installation in Naperville.

An AC runs $5,000–$10,000 installed, sized with a Manual J load calculation instead of a copy of the old unit's tonnage. A standard swap takes one day. See AC installation in Plainfield or AC installation in Naperville.

A complete system, furnace and AC together, runs $10,000–$20,000 and usually takes one to two days. The full HVAC replacement cost breakdown explains why replacing both at once tends to cost less per system than doing them years apart. We install and service all major brands, so the estimate is built around your house, not one manufacturer's catalog.

Prices don't change at the city line. Permits do, and so does who issues them.

Plainfield. Inside Village of Plainfield limits, a like-for-like furnace change-out doesn't need a permit. Some homes with a Plainfield mailing address sit in unincorporated Will County, though, and those do need a permit, from Will County rather than the village. A Plainfield address on your mail doesn't tell you which one you are.

Naperville. The City of Naperville issues permits citywide, on both the DuPage County and Will County sides of town. Its Guide to Building Permits says no permit is required for an in-kind furnace or A/C replacement.

In both cases the rule covers a like-for-like swap. Where a job does need a permit, filing it is part of the job, not something you chase down yourself. Neither town's rules change the price on this sheet.

This is the bigger difference, and it can be worth real money on a replacement.

Naperville runs its own electric utility. Naperville homes buy power from the City of Naperville Electric Utility, not ComEd, and the city pays its own equipment incentives, as funding allows. Per the city's Central Air Conditioner Incentive page, a replacement central AC of 15.2 SEER2 or higher (residential size, 65,000 Btu/hr or less) earns a $700 incentive. Its Air Source Heat Pump Incentive page lists $900 for a heat pump at 15.2 SEER2 or higher, $1,400 at 17 SEER2 or higher while keeping the furnace for backup, and $1,800 at 17 SEER2 or higher without one, with a minimum of 8.1 HSPF2.

Both city programs have the same conditions: a complete application within 120 days of installation, existing homes only (new construction isn't eligible), one incentive per household, and payment as a one-time credit on your utility bill. The city rates equipment by its AHRI certificate, which covers the matched condenser, coil, and furnace, so your quote should list all three model numbers. The city also offers a $25 AC tune-up incentive, but only to customers contributing to its Renewable Energy Program.

Plainfield is typically ComEd and Nicor Gas. ComEd's Home Heating & Cooling program offers instant discounts on high-efficiency heat pumps and smart thermostats; the page doesn't list amounts and says program details can change with funding. On the gas side, Nicor Gas's 2026 residential rebates pay $150 for a furnace of 95% AFUE or higher and $225 at 97% or higher ($200 and $275 with a smart thermostat on the same application), for installs during 2026, applied for within 90 days or by January 31, 2027. An 80% AFUE furnace doesn't qualify.

These programs change, and some run out of money mid-year. We confirm the current incentives on your quote rather than promising a number that may already be stale. More on both towns is on the Plainfield HVAC page and the Naperville HVAC page.

Service prices are flat. Replacement prices move, and they move for the same reasons in both cities.

Use it as a baseline, including against us. Ask any company for its diagnostic fee and its tune-up price before booking, and ask whether repairs are quoted in writing before work starts. A company that won't name a service-call price on the phone is telling you something.

For replacements, ask for a written, itemized quote with a Manual J and a ductwork check, and compare those line by line. How to choose an HVAC company in Plainfield covers the rest of the checklist.

If your system is down, book a repair visit: furnace repair in Plainfield, furnace repair in Naperville, or AC repair in Plainfield. If you're pricing a replacement, book a free estimate and get the range on this page turned into one written number.