Central air conditioning systems utilize a variety of refrigerants, most of which are generically called "Freon." While the chemical composition of refrigerant has improved over the years, it is still a threat to the environment and must be carefully contained within the system. A sealed system, not to be serviced by the homeowner, is not intended to leak refrigerant during its lifetime. Unfortunately for the environment and the expense of the homeowners, though, AC units are likely to develop a small leak at some point; however, the lost refrigerant can be replaced.
What is Freon?
Freon is the brand name of a coolant developed by DuPont in the 1920s as a safe alternative to noxious chemicals used in refrigerator units. As the development of air conditioning evolved, Freon became the industry standard. The product, simply referred to as "R-22," was removed from the market in 1987 due to a phase-out of ozone-depleting chlorofluorocarbons. At the time of publication, DuPont manufactures R-410A, which is still generically referred to as "Freon" but is actually branded as "Suva."
Freon, contained in a closed loop inside the AC system, is added when the unit is brought online. With no vents and no means to evaporate outside its confines, the chemical should last the lifetime of the unit. However, leaks in AC systems are fairly common and typically occur at a pressure point and in locations that leave the piping vulnerable. If a leak is suspected, the first place to look is the compressor unit located outside the home. This unit, which is usually a large round device with a fan, can be easily damaged by children, animals and lawn mowers. Repairs to this unit can be costly. A far greater problem occurs when a leak is within a wall. This is often due to homeowners placing nails in walls for shelves or hanging pictures and unintentionally puncturing the soft copper tubing embedded in the walls.
A homeowner's first indication of a possible Freon leak is the lack of cooling power from the AC system. Looking for escaped coolant can be difficult, as it tends to evaporate rapidly. If the Freon is around, look for a greasy, slightly viscous liquid. If the refrigerant has evaporated, look for white residue on or near the unit's pipes. An AC professional uses an electronic sniffing device that can pinpoint a leak and help determine the proper course of action. Minor leaks are not repaired, but rather a sealant is introduced into the line along with replacement refrigerant. Major leaks may require replacing one or more of the components that make up the system.
How Much Freon Is in an HVAC Unit?
Freon is measured in pounds. While the perfect unit, operating without any kind of failure, won't lose any Freon, a unit that requires servicing of any kind loses some Freon just from having the service technician's manifold gauge attached for a pressure check. Addition refrigerant can leak out of the Schroeder valves located at the compressor due to failure of the rubber seals. As for how much Freon is in each unit that could be lost due to damage, the general rule of thumb is 2 1/2 pounds of refrigerant per ton of cooling. The tonnage of an AC unit determines its size and the amount of space it can cool, with larger tonnage units providing greater cooling abilities. Since Freon is a gas, precise figures vary with air temperature and pressure.