Estimated Read Time: 10 minutes
When you are without cooling, every hour counts. So how long does AC installation take, and what really affects the schedule? Here’s a clear, St. Louis–focused guide to help you plan, avoid surprises, and get your home cool again fast. If you are shopping now, ask about our free estimate and flexible financing to keep your project on track.
How Long Does AC Installation Take?
Most single-family AC replacements finish in one working day. A straightforward split system, with no duct repairs and accessible equipment, typically takes 6 to 10 hours from arrival to final walkthrough. Homes that need ductwork changes, electrical upgrades, or indoor air quality add-ons can extend to a second day.
General ranges we see in the St. Louis area:
- Standard AC or heat pump changeout with compatible ductwork: 6 to 10 hours.
- Full system replacement (furnace/air handler and AC or heat pump) with minor modifications: 1 day, sometimes 1.5 days.
- Installations with significant duct repairs, new line sets through finished spaces, or attic-only access: 1.5 to 2 days.
- Specialty installs, high-efficiency communicating systems with zoning, or condo/rooftop projects: 2 to 3 days.
Our goal is a clean, code-compliant, right-sized install that performs on day one and years after. Cutting corners to save an hour costs comfort and money later.
What Factors Speed Up or Slow Down an AC Installation?
Several variables determine your timeline. The big ones:
- Equipment match and accessibility
- Location of the indoor unit (basement, closet, attic) and outdoor pad or rooftop.
- Clearances for code and service.
- Ductwork condition
- Proper sizing, leakage, and insulation. Leaky or undersized ducts call for repairs or resizing.
- Electrical readiness
- Correct breaker size, disconnect, and grounded outlet for the condensate pump if used.
- Refrigerant line set
- Reuse vs new lines. New lines through finished walls or long runs add time.
- Condensate and drain routing
- Gravity drain vs pump, secondary drain pan in attics, and float switch placement.
- Controls and thermostat
- Standard vs communicating controls, zoning panels, and sensor placement.
- Add-ons and indoor air quality
- Air cleaners, UV lamps, humidifiers, or dehumidifiers add installation steps.
- Permits and inspections
- Municipal requirements and scheduling. We pull permits and coordinate the inspection.
- Weather and site logistics
- Heavy rain, extreme heat, or limited parking can slow outdoor and rooftop work.
Local tip: St. Louis summers bring high humidity, which makes attic work hotter and slower. Early start times and proper ventilation help keep schedules on track.
What Happens on Installation Day? A Step-by-Step Walkthrough
Knowing the sequence helps you plan your day and spot professional workmanship.
- Arrival and home protection
- Floor coverings and protective runners go down. Tools and materials are staged.
- Decommission and remove old system
- Recover refrigerant per EPA standards. Disconnect, cap, and remove equipment.
- Set outdoor unit and pad
- Level the pad, set the condenser or heat pump, and align for service clearances.
- Line set and brazing
- Run new copper or verify existing lines are clean and sized correctly. Braze with nitrogen flowing to prevent oxidation.
- Evacuation and charge
- Pull a deep vacuum (target 500 microns). Weigh in charge, then verify with superheat and subcooling.
- Electrical and safety devices
- Install new disconnect if needed, tighten lugs to spec, and add surge protection if selected.
- Indoor unit and airflow
- Set the air handler or coil, seal transitions, confirm blower orientation, and set airflow to design CFM.
- Controls and thermostat
- Wire the thermostat, integrate any zoning or IAQ equipment, and confirm communication.
- Commissioning and test run
- Check static pressure, delta T, amperage, and refrigerant metrics under load.
- Clean up and homeowner walkthrough
- Remove debris, review system operation, and explain filter changes and maintenance.
Commissioning is not optional. It validates performance and protects your warranty.
Ductwork: The Biggest Wildcard
Airflow quality determines comfort and efficiency. Here is how duct status changes the timeline:
- Good ducts, verified with static pressure and simple visual checks: no added time beyond sealing small gaps.
- Minor repairs: sealing, adding returns, or resizing a few runs may add 2 to 6 hours.
- Major corrections: replacing trunk lines, adding zones, or fixing collapsed or uninsulated ducts can add 1 to 2 days.
If your rooms cool unevenly, are noisy, or have dust issues, expect some duct attention. It is worth it. A right-sized system on bad ducts will still underperform.
Heat Pump vs Traditional AC: Any Difference in Time?
For most homes, a heat pump replacement takes about the same time as a standard AC replacement. Where time increases:
- Dual-fuel setups with a gas furnace add controls and safety checks.
- Cold-climate heat pumps or variable-speed systems require more commissioning.
- Thermostat and outdoor sensor wiring can add steps.
Our team installs both AC and heat pump systems every week. We will recommend the option that fits your home’s envelope, comfort goals, and utility rates.
Retrofit vs New Construction
- Retrofit replacement in existing homes: 1 to 2 days depending on access and ductwork.
- New construction or full gut remodels: schedules vary with trades and inspections. We coordinate with your builder to keep the critical path moving.
For commercial properties with rooftop units or chillers, crane time, safety plans, and permits affect duration. Our commercial team handles these logistics end-to-end.
How We Keep Your Install On Schedule
Air Comfort Service, Inc. has refined an installation process that balances speed with precision:
- Skilled, credentialed teams
- Carrier Factory Authorized Dealer and multi-time Carrier President’s Award winner. Technicians train continuously on the latest equipment.
- Permits and paperwork handled
- We pull permits, meet code, and file warranty paperwork so you do not lose coverage.
- Right-sizing and planning
- Load calculations, duct checks, and site photos reduce surprises on install day.
- Clean, safe workspace
- Home protection, daily cleanup, and careful staging keep work moving without mess.
- Surge protection option
- We recommend and install HVAC surge protection devices to protect new systems from power events.
- Aftercare built in
- Preferred Partner Plan with two HVAC system checks per year, priority service, and discounts keeps your system efficient and avoids breakdowns.
Two hard facts to consider as you plan:
- We have served St. Louis homeowners since 1969.
- Our Preferred Partner Plan includes two HVAC system checks annually and starts at $19 per month.
Cost-Saving and Scheduling Tips for St. Louis Homeowners
- Book shoulder-season installs
- Spring or fall appointments are easier to schedule and may finish faster.
- Clear access before the crew arrives
- Move cars, pets, and fragile items. Clear 3 to 4 feet around indoor and outdoor equipment.
- Decide on add-ons during the estimate
- Air cleaners, UV, humidifiers, or dehumidifiers are quicker to install during the main job.
- Consider financing to avoid delays
- We offer flexible options, including 0% plans for qualified buyers.
- Plan for attic or crawlspace time
- Early start times help beat midday heat, which can slow attic work in July.
After Installation: Inspections, Warranty, and Maintenance
- Municipal inspection
- We coordinate the inspection where required. You may need brief access for the inspector.
- Warranty
- We register your equipment so the manufacturer warranty starts correctly.
- Maintenance plan
- Join the Preferred Partner Plan. You get two system checks per year, priority service, and exclusive discounts. Routine care reduces energy costs and helps keep your warranty intact.
What you can do next:
- Replace or clean filters on schedule.
- Keep the outdoor unit free of debris and vegetation.
- Call us if you notice odd sounds, poor airflow, or uneven temperatures.
Signs It May Be Time to Replace, Not Repair
- Your system is 12 to 15 years old and has frequent breakdowns.
- Repair costs exceed 30 to 40 percent of a new system.
- Comfort is inconsistent across rooms.
- Your energy bills are rising despite maintenance.
- The unit uses outdated refrigerant and parts are hard to source.
If you are unsure, we will compare repair vs replacement with clear numbers and a free estimate on a new AC system.
Special Offer
Save on your project planning. Special Offer: Free Estimate on AC Installation. Contact us today for a free estimate on a new A/C system. Call 314-814-8455 or visit https://www.aircomfortservice.com/ to schedule.
What Homeowners Are Saying
"Fantastic job on installing new AC and Furnace. Very professional and so appreciate the quick installation." –St. Louis Homeowner
"The entire team was awesome. Installed a new AC unit and furnace and everything went perfect and looks incredible. I couldn’t be happier with the entire experience." –St. Charles Homeowner
"Tyler and Tim arrived on time... The installation process for furnace and air conditioning units were seamless... Cleanup was excellent. Could not have asked for better technicians!" –O'Fallon Homeowner
"Great team at Air Comfort! Efficient install. Workers were helpful and hardworking. They explained everything and left no mess!" –Chesterfield Homeowner
Frequently Asked Questions
How long does AC installation take for a typical St. Louis home?
Most changeouts finish in 6 to 10 hours. If ductwork, electrical upgrades, or add-ons are needed, plan for 1.5 to 2 days.
Do I need to be home during the entire installation?
You do not need to stay all day. Please be present for the initial walkthrough and final handoff so we can review controls and maintenance.
Will you pull permits and handle inspections?
Yes. We pull required permits for your city and coordinate the inspection. We also file your equipment warranty for you.
Can you install during rain or extreme heat?
Light rain is fine. Severe weather or lightning can pause outdoor work. Attic installs may take longer during extreme heat.
What can I do to help the job finish faster?
Clear access to equipment, decide on add-ons before install day, secure pets, and ensure outdoor space for the crew and materials.
In Summary
Most AC installations wrap up in one day, but ductwork, access, and add-ons can extend the schedule. For a smooth, code-compliant project in St. Louis, plan with a pro who explains each step and commissions the system right.
Ready to Get Started?
Call 314-814-8455 or schedule at https://www.aircomfortservice.com/ for your free estimate on AC installation in St. Louis. Ask about 0% financing and our $19/month Preferred Partner Plan to protect your new system.
Call now: 314-814-8455. Or book online at https://www.aircomfortservice.com/ for your free AC installation estimate. Protect your investment with two annual system checks starting at $19/month in our Preferred Partner Plan.
About Air Comfort Service, Inc.
Family-owned and proudly serving St. Louis since 1969, Air Comfort Service, Inc. is a Carrier Factory Authorized Dealer with an A+ BBB rating. Our licensed installers pull permits, protect your home, and file your warranty. We offer 24/7 availability, flat-rate pricing, and flexible financing options, including 0% plans for qualified buyers. Our Preferred Partner Plan keeps systems efficient with two annual checks and priority service.