HVAC terms in plain English

SEER2 (Seasonal Energy Efficiency Ratio 2) measures how much cooling a system delivers per unit of electricity over a season. It replaced the older SEER metric on January 1, 2023, using a tougher test that reflects real ductwork. Higher numbers cost more upfront but less to run. In Texas (the DOE’s South region) the legal minimum is 14.3 SEER2; ENERGY STAR certification starts at 15.2, the federal tax credit at 17.0, and the New Braunfels Utilities rebate at 18.

Source: U.S. Department of Energy

The Texas Department of Licensing and Regulation (TDLR) is the state agency that licenses air-conditioning and refrigeration contractors. Every legitimate HVAC contractor in Texas holds a TDLR license, and the public can verify one’s status, class, and expiration free of charge at the TDLR license search.

Source: TDLR license search

Texas issues air-conditioning contractor licenses in two classes. A TACLA (Class A) license covers systems of any size, including commercial. A TACLB (Class B) license covers residential and light-commercial systems under 25 tons. For a typical home, a Class B contractor is fully qualified. Individual technicians work under a licensed contractor.

Source: TDLR ACR program

NATE (North American Technician Excellence) is the leading voluntary certification for HVAC technicians. It tests real-world installation and service knowledge. It is a quality signal layered on top of the legally required TDLR license, not a replacement for it.

Source: NATE

Section 608 of the Clean Air Act requires that any technician who opens a system and handles refrigerant hold an EPA Section 608 certification. It is a federal legal requirement, so a technician charging or recovering refrigerant without it is working illegally.

Source: U.S. EPA

R-410A is the hydrofluorocarbon refrigerant used in most residential AC systems installed before 2025. Under the EPA’s AIM Act, manufacturing of new residential systems using R-410A ended January 1, 2025, in favor of lower-global-warming refrigerants such as R-454B. Existing R-410A systems remain legal to service, but parts and refrigerant will grow scarcer and pricier over time.

Source: U.S. EPA (AIM Act)

Tonnage measures an air conditioner’s cooling capacity: one ton equals 12,000 BTU per hour, roughly the cooling for 500–600 square feet. The right tonnage comes from a load calculation, not a rule of thumb. An oversized system short-cycles and wastes energy; an undersized one runs constantly and wears out early.

Source: U.S. Department of Energy

A load calculation determines exactly how much heating and cooling a home needs, accounting for square footage, insulation, windows, orientation, and local climate. The industry standard method is ACCA Manual J. A contractor who sizes a system by Manual J rather than by guesswork or by simply matching the old unit is doing the job properly.

Source: U.S. Department of Energy

The condenser is the outdoor half of a split air-conditioning system. It contains the compressor and a coil that releases the heat the system has removed from indoor air. It pairs with an indoor air handler or coil; replacing one without matching the other is generally not recommended.

Source: U.S. Department of Energy

The air handler is the indoor component that circulates conditioned air through the home’s ductwork. It houses the evaporator coil and blower. In a matched system it is paired with the outdoor condenser; the two are designed and rated to work together.

Source: U.S. Department of Energy

The evaporator coil sits inside the air handler and absorbs heat from the air passing over it — that is what cools your home. Restricted airflow (a dirty filter or blocked vents) or low refrigerant can drop its temperature below freezing, icing it over so the system blows warm air. Thawing it (turn cooling off, fan on) restores airflow, but a coil that refreezes points to a deeper problem for a licensed technician.

Source: Carrier