What an AC replacement includes
A central AC has two halves, the condenser outside and the evaporator coil inside. The coil sits on the furnace or inside the air handler in the attic or a closet. We replace both together because AHRI, the group that certifies AC ratings, rates the indoor and outdoor units as a pair, so a new unit’s rating holds only with its matching coil.
We check the copper refrigerant lines between the two units. For newer R-454B systems, Rheem’s installation instructions call for flushing an old line set with nitrogen before reuse and recommend replacing it. We recover the old refrigerant, and the old equipment leaves with us.
Sizing the new AC to your house
We size your new AC with a Manual J load calculation, a method from ACCA (the Air Conditioning Contractors of America) that works from the house itself. It accounts for room sizes, windows and which way they face, insulation, and the attic. Austin’s residential code adopted in 2025 requires equipment to be sized from that kind of calculation. The old unit’s size is only a starting point because the house may have changed since it went in, with new windows, more insulation, or an addition.
Install day
The city permit is in place before we start, and we recover the refrigerant, remove the old condenser and coil, and set the new ones. We braze the refrigerant lines, pressure-test them with nitrogen, and pull them into a vacuum before charging the system. Swapping both units on existing ducts is usually a one-day job. We start the system, check the refrigerant charge and airflow, and show you the thermostat and filter.
What to have ready
A few things make install day go smoothly:
- A clear path to the outdoor unit and the attic hatch or equipment closet.
- Room around the indoor unit, with boxes and holiday decorations moved out of the attic walkway.
- Pets kept away from open doors and work areas.
- Someone home at the start and end for the walkthrough.
- The gate code or side-gate key, if there is one.
What AC replacement costs in Austin
Angi’s Austin page, updated August 2026, publishes an average AC replacement cost in Austin of $5,966, with a normal range of $4,135 to $7,811. Our AC replacement cost guide covers how size, efficiency level, and duct and line work affect the price, and how other published ranges compare.
Efficiency, refrigerant, and permits
In Texas, the U.S. Department of Energy standard since January 1, 2023 requires a new split-system AC under 45,000 Btu/h to have an efficiency rating of at least 14.3 SEER2. The EPA says new systems made since January 1, 2025 use newer refrigerants such as R-454B, with R-410A systems built before then still able to be installed while supply lasts. Inside Austin city limits, the City requires a mechanical change-out permit and a final inspection for an AC changeout. Our SEER2 and refrigerant guide covers these rules and the permits in nearby cities.
AC replacement questions
Can you replace just the outdoor unit?
Sometimes we can replace just the outdoor unit if the indoor coil is fairly new and certified as a match. Each outdoor unit is certified with specific indoor coils, and a federal rule bars installing one in the South if any of those certified combinations falls below the federal minimum for the region. An R-454B outdoor unit needs an indoor coil approved for R-454B, which rules out most older coils, and Austin Energy’s rebate requires the whole system to be replaced.
What size AC does my house need?
A load calculation on your house determines your AC size using information beyond square footage. The calculation uses an outdoor summer design temperature, which ACCA’s table lists as 98°F for Camp Mabry, Austin’s official weather station. An oversized unit cools the house fast and shuts off before it pulls the humidity out.
Do you replace the air handler too?
Yes, we replace the air handler when the coil sits inside it, as it usually does in homes with electric heat or a heat pump. In a home with a gas furnace, the coil sits on top of the furnace, which can stay if it’s in good shape. We’ll tell you which setup you have at the visit.