HVAC System Replacement Cost in Mount Prospect, Illinois
Full HVAC system replacement in Mount Prospect runs about $18,300 for a typical job. Basic installs start near $11,100. High-efficiency equipment with duct or electrical work can reach $24,200.
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Mount Prospect Weather and HVAC Load
In a normal year, Mount Prospect racks up 6,085 heating and 933 cooling degree days (NOAA 1991-2020 normals). Heating is the bigger job here, and furnaces and heat pumps in Mount Prospect put in far more hours than the air conditioner. A normal year brings 122 nights at or below freezing and 17 days over 90°F. Snowfall averages about 38 inches. For a 2,000 sq ft house, this climate points to a heating load somewhere near 65,000 BTU/h. Treat that as a starting number. A Manual J calculation will move it up or down based on insulation and windows.
| Heating degree days / year | 6,085 |
|---|---|
| Cooling degree days / year | 933 |
| Nights at or below 32°F | 122 |
| Days above 90°F | 17 |
| Average low / high | 42.3°F / 59.2°F |
Mount Prospect Housing Stock
Census figures put the median build year in Mount Prospect at 1969, so a typical house here has about 57 years on it. A lot of these homes are on their second or third system by now. The ductwork is usually original, and leaky joints are common. Mount Prospect has roughly 15,000 owner-occupied homes, or 70% of households. The median home value is $377,000, and median household income is $103,911. We use both figures to adjust labor and pricing for this page.
NOAA storm reports for Cook County show 27 hail days and 75 days with damaging thunderstorm winds over the six years from 2020 to 2025. The largest hail reported was 2.75 inches across. Hail flattens the thin aluminum fins on condenser coils and cuts airflow. After a big storm, take a look at the outdoor unit; homeowners insurance often covers the damage. Cook County also had 8 tornado days in that period. In Mount Prospect, 18.3% of residents are 65 or older. For older adults, a house with no heat in January or no AC during a heat wave is a medical risk. Mention it when you call, since many companies put those calls first.
When Replacement Makes Sense
- An old R-22 AC paired with an aging furnace
- Some rooms are uncomfortable, and the energy bills are high
- Both units keep needing repairs
What Moves the Price
- Furnace plus AC, or heat pump plus air handler
- Efficiency ratings: SEER2, AFUE and HSPF2
- Thermostat and zoning upgrades
- Permits and electrical work
- Equipment sized to the house and climate
- Duct repair or replacement
We raised the national figures about 31% for Mount Prospect using local income, home values and the equipment size this climate needs. Real bids can still come in outside the range, so collect three written quotes.
What the Quote Should Cover
- Startup, testing and warranty registration
- A load calculation and system design
- New, matched heating and cooling equipment
- Duct connections and sealing
- Removing the old equipment
Illinois Permits, Efficiency Rules and Rebates
Illinois falls in the DOE's North region. New split central air conditioners must meet at least 13.4 SEER2, and heat pumps sold anywhere in the U.S. need 14.3 SEER2 and 7.5 HSPF2. Equipment replacements in Mount Prospect generally need a mechanical permit, and a reputable contractor will pull it for you. Ask for their Illinois license or registration number and a certificate of insurance with the quote. The federal 25C tax credit ended for equipment installed after December 31, 2025, so incentives now come mostly from utilities and state programs. Check your electric and gas utility's rebate page before you pick equipment.
Before You Hire
- Get one quote for a heat pump system and one for a furnace plus AC.
- Replacing both pieces at once usually costs less than two separate jobs a few years apart.
- Ask for a duct leakage test. Leaky ducts can lose 20 to 30% of what the system puts out.
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HVAC System Replacement Questions from Mount Prospect Homeowners
How much is full HVAC system replacement in Mount Prospect?
Plan on $11,100 to $24,200, with most jobs near $18,300. Equipment efficiency, house size and the condition of the ducts and wiring decide where your quote falls.
When is the best time to schedule full HVAC system replacement in Mount Prospect?
Between late spring and early fall. Mount Prospect averages 122 freezing nights a year, and heating calls spike from November through February.
Can I replace only the AC and keep my furnace?
Yes, as long as the indoor coil and blower work with the new AC. A mismatched system loses efficiency and can void the warranty.
How often should an HVAC system be replaced?
Most systems get replaced every 15 to 20 years. AC units and heat pumps usually wear out before gas furnaces do.
HVAC System Replacement Near Mount Prospect
- Des Plaines $10,500 to $22,800
- Arlington Heights $11,700 to $25,600
- Oak Lawn $9,700 to $21,200
- Berwyn $9,600 to $20,900
- Orland Park $10,800 to $23,500
- Tinley Park $10,800 to $23,600
- Wheaton $11,900 to $26,000
- Skokie $10,900 to $23,700
Sources: U.S. Census Bureau ACS 5-year estimates 2019-2023 and 2024 population estimates; NOAA NCEI U.S. Climate Normals 1991-2020, station Chicago Palwaukee Airport; NOAA Storm Events Database 2020-2025, Cook County. Prices are our estimates, not contractor quotes. Updated 2026.