Electric air conditioning is the most common type of cooling system in homes, businesses, and vehicles. It uses electricity to power a compressor that circulates refrigerant through a closed loop, absorbing heat from indoor air and releasing it outside. Nearly every central air conditioner, window unit, mini-split, and heat pump sold today is an electric air conditioning system. A typical home unit draws between 1,200 and 3,500 watts depending on its size and efficiency rating.
How the Cooling Cycle Works
Electric air conditioning relies on a principle called vapor compression. A chemical refrigerant flows through four stages in a continuous loop, changing between liquid and gas states to move heat from one place to another. Electricity powers the compressor that keeps this cycle running.
In the first stage, the compressor squeezes refrigerant gas, raising its pressure and temperature. That hot, pressurized gas flows into the condenser coil (the part outside your home), where it releases heat into the outdoor air and condenses into a liquid. The liquid refrigerant then passes through an expansion valve, which drops its pressure suddenly and makes it very cold. Finally, this cold refrigerant enters the evaporator coil (inside your home), where it absorbs heat from your indoor air as it boils back into a gas. The cycle then repeats.
The key insight is that an electric AC doesn’t generate cold air. It removes heat. The refrigerant acts as a shuttle, picking up warmth inside and dumping it outside. The electricity is there to run the compressor and fans that keep the refrigerant moving and air flowing across the coils.
Core Components
The compressor is the heart of any electric air conditioning system. It draws in low-pressure refrigerant gas from the evaporator and compresses it into a high-pressure, high-temperature state before sending it to the condenser. Residential systems typically use one of two compressor designs: reciprocating compressors, which use a piston-like back-and-forth motion to compress the gas, and rotary compressors (including scroll types), which use a spinning motion to achieve compression. Scroll compressors have become the standard in most home systems because they run quieter and have fewer moving parts.
Beyond the compressor, the system includes the condenser coil and fan (outdoor unit), the evaporator coil (indoor unit), and the expansion valve that controls refrigerant flow. A blower fan inside pushes your home’s air across the cold evaporator coil, and the cooled air circulates through your ductwork or directly into the room in ductless systems.
How Much Electricity They Use
Power consumption depends heavily on the unit’s size and efficiency. Size is measured in tons of cooling capacity, with most homes using a 2- to 4-ton system. Efficiency is measured in SEER2, a rating that represents how much cooling you get per watt of electricity.
A 3-ton central air conditioner with a 16 SEER rating draws about 2,250 watts while running. A smaller 2-ton unit at the same efficiency uses around 1,500 watts, while a large 5-ton system can pull 3,750 watts or more. Higher-efficiency models use noticeably less power: that same 3-ton unit at 20 SEER drops to roughly 1,636 watts. Over a full cooling season, upgrading from a 14 SEER to a 20 SEER system can cut your cooling electricity use by about 30%.
For context, running a 3-ton system for 8 hours a day at average U.S. electricity rates adds roughly $5 to $8 per day to your electric bill, depending on efficiency and local rates.
Heat Pumps: Cooling and Heating in One
A heat pump is an electric air conditioner that can run in reverse. It contains a component called a reversing valve that switches the direction of refrigerant flow. In cooling mode, it works exactly like a standard AC, moving heat from inside to outside. In heating mode, it flips the cycle: the outdoor coil absorbs heat from the outside air, and the indoor coil releases that heat into your home.
This works even in cold weather because refrigerant can absorb heat from outdoor air at surprisingly low temperatures. Modern heat pumps perform well down to about 5°F, though their efficiency drops as temperatures fall. Because a heat pump moves heat rather than generating it (like a furnace does), it can deliver two to three times more heating energy than the electricity it consumes.
Current Efficiency Standards
As of January 2023, the U.S. Department of Energy requires all new central air conditioners and heat pumps to meet updated minimum efficiency standards using the SEER2 rating system, which reflects a more realistic testing method than the older SEER scale.
The minimums vary by region. In the northern United States, new central air conditioners must meet at least 13.4 SEER2. In the South and Southwest (including states like Texas, Florida, Arizona, and California), the minimum is 14.3 SEER2. Heat pumps have a national minimum of 14.3 SEER2 regardless of region. If you’re replacing an older system, any new unit you buy will meet or exceed these thresholds.
Refrigerant Changes
The refrigerant inside your AC system is changing. For the past two decades, most residential systems used R-410A, a chemical that doesn’t damage the ozone layer but has a high global warming potential. The EPA is now phasing down these compounds under federal rules aimed at reducing their climate impact.
Newer systems are transitioning to lower-impact refrigerants like R-454B and R-32, both of which fall below the EPA’s limit of 700 global warming potential for residential air conditioners. R-32, for example, is already approved and in use in U.S.-manufactured equipment. These newer refrigerants are classified as mildly flammable, so they can only be used in systems specifically designed for them. You cannot simply swap the refrigerant in an older R-410A system for a newer type.
Electric AC in Vehicles
In gas-powered cars, the AC compressor is traditionally driven by a belt connected to the engine. Electric vehicles take a different approach: they use a high-voltage electric compressor powered directly by the vehicle’s battery pack. These compressors run on 400 volts or more and serve multiple roles beyond cabin cooling, including keeping the battery pack and drivetrain at safe operating temperatures.
The advantage of an electric compressor is that it runs independently of engine speed (since there is no engine), so it can adjust its output precisely based on demand. The tradeoff is that running the AC in an EV draws from the same battery that powers the wheels, which can reduce driving range by 10% to 20% on hot days depending on conditions and the vehicle.