The most common installation mistake has nothing to do with brands. It is replacing a system with the same size as the old one without checking whether the old one was ever right. A room-by-room load calculation, known in the trade as a Manual J, looks at the square footage, insulation, windows, orientation and air leakage. An oversized system cools quickly and shuts off before it has pulled the humidity out, which leaves the house cool but clammy and wears the equipment out with constant starts and stops.
A replacement is the right time to fix sizing and duct problems the old system was living with.
What has changed
Efficiency minimums. In Texas and the rest of the southern region, a new home-sized central air conditioner must meet at least 14.3 SEER2.
New refrigerants. Most new systems use R-454B or R-32 rather than R-410A. The refrigerant usually comes with the brand; installation quality matters more.
No federal tax credit. The federal 25C credit ended for equipment installed after December 31, 2025.
Local rebates still matter. If Austin Energy is your electric utility, a qualifying new system may earn a rebate. Some systems, such as those with electric resistance heat, do not qualify. See Austin Energy rebates before you sign.
Permits and inspection
Inside Austin city limits, replacing HVAC equipment generally requires a mechanical permit, and the work is inspected. Ask the installer to pull the permit and arrange the inspection, and keep the paperwork. Buyers, lenders and Austin Energy rebate programs may all ask for it later.
Check the ducts before you replace
A new system connected to leaky, crushed or undersized ducts will never perform the way the label says. In attic installations, ask the installer to check the ducts for leaks and damage, and to look at whether the return air path is big enough. Austin Energy has offered rebates for duct sealing in some programs.
Ducts in a hot attic lose cooling through every leak. Check them before paying for a new system.
