What Happens During AC Installation?
AC installation takes 1 to 3 days: one day for a straightforward replacement, two to three if the ductwork needs modification or repair. Knowing the sequence helps you verify the work is being done correctly, from equipment delivery and old system removal through installation, refrigerant charging, and startup testing.
Day 1: Equipment Delivery and Old System Removal
The installation begins with delivery of the new equipment (outdoor condenser and indoor air handler or coil). The technician shuts off power to the existing system and recovers the existing refrigerant into an EPA-approved recovery cylinder federal law requires capturing existing refrigerant rather than venting it. The old equipment is disconnected and removed. The installation site (pad for the outdoor unit, air handler location) is inspected and prepared for the new equipment. (For more on this, see How Long Does a New AC System Last?.) ENERGY STAR publishes certified efficiency ratings for heating and cooling equipment, which is the cleanest way to compare models.
Equipment Installation and Connection
The new outdoor condenser is set on the pad and the new air handler (or evaporator coil on an existing air handler) is positioned. Refrigerant lines (suction and liquid lines) connect the indoor and outdoor units. Electrical connections are made the outdoor condenser connects to the disconnect and main panel; the air handler connects to its circuit. The condensate drain line is connected and the drain is tested for proper flow. Ductwork connections are inspected and sealed.
Refrigerant Charging and System Startup
After all connections are made, the technician pressurizes the system with nitrogen to check for leaks. After a successful pressure test, a vacuum is pulled on the refrigerant circuit to remove air and moisture before refrigerant is added. The system is charged with refrigerant to manufacturer specifications the technician measures superheat and subcooling readings to verify the correct charge. The system is started and run through a complete operational test: checking supply and return air temperatures, verifying thermostat operation, and confirming the system reaches the set temperature. (For more on this, see Questions to Ask Before Getting a New AC System.)
Working With a Contractor on This Project
Getting the right outcome on any home services project starts before the work begins. A few consistent practices make the difference between a smooth project and a frustrating one.
Get at least two or three quotes. A single quote gives you no basis for comparison. Two or three quotes reveal the market rate for the work, expose scope differences between bidders, and let you assess contractor communication quality before any commitment is made. The lowest bid is not automatically the best value if the scope is thin or the materials are underspecified.
Ask for licenses and insurance before work starts. Verify current general liability insurance and, for any work involving workers on your property, workers compensation coverage. Licensing requirements vary by state and trade; confirm the specific requirements in your jurisdiction. A licensed contractor who carries appropriate insurance protects both parties if something goes wrong during the project.
Get the scope in writing. A written proposal that specifies materials, labor scope, timeline, what is included (permits, cleanup, disposal), and warranty terms is the foundation of a professional engagement. Verbal agreements on any of these points invite misunderstanding. For any project over $500, written scope is non-negotiable.
Clarify the payment schedule upfront. A reasonable payment schedule ties major payments to project milestones: a deposit at signing, a payment at material delivery or project start, and a final payment at completion after a walkthrough confirms satisfaction. A contractor who requires full payment upfront before work begins is a red flag in any trade.
Making a Confident Decision
The information in this article is designed to help you ask better questions of the professionals you work with, evaluate their answers with more confidence, and understand the decisions involved in this type of home services project. It is not a substitute for professional assessment of your specific home.
Every home is different. Roof slopes, local weather, tree exposure, soil conditions, and existing system condition all affect what the right solution is for your specific situation. The general principles here apply broadly, but a professional who assesses your home in person will give you guidance that accounts for the details that general articles cannot.
When you are ready to move forward, getting at least two or three quotes from licensed, insured, local contractors is the most important practical step. It lets you compare approaches, assess contractor quality, and confirm that the solution proposed matches your specific situation and budget.
AC Installation Cost at a Glance
Unit size and tonnage: Larger homes need larger systems, which cost more.
Efficiency rating (SEER2): Higher-efficiency units cost more upfront but lower bills over time.
Ductwork and installation complexity: New or modified ductwork raises the total significantly.
Overall range: $6,000 to $15,000, averaging $8,500 for a standard replacement in a home with usable ducts.
Cost figures on this page were checked against published pricing on September 2, 2026. How we source cost data.