According to PG&E, most central air conditioning systems use two to four pounds of refrigerant per ton of cooling capacity. A three-ton air conditioner would typically have six to 12 pounds of refrigerant for a proper charge.
When estimating the amount of refrigerant in a residential A/C unit, the general rule that is used is in the 2-4 pounds per ton of cooling. For instance, recharging a 3-ton A/C with a 35-foot line set from empty level will need an approximately 6-12 pounds of refrigerants.
The general guideline used when calculating the amount of Freon in a residential A/C unit is 2-4 pounds per ton of cooling. For example, if you install a new A/C system rated for a five-ton load, the system will require 10-20 pounds of refrigerant.
Typical residential systems hold between 5 and 20 pounds of refrigerant. On average it's about 3 pounds per ton (12,000 BTU) of air conditioning.
On average, most residential AC systems require between 2 to 4 pounds of Freon per ton of cooling capacity. However, the exact amount depends on several factors, including the size of your system, its age, and whether there are any leaks.
As mentioned earlier, Freon costs about $125 – $150 per pound. Most homeowners will pay in the range of $200 to $400 for a refill, depending on the type and size of their HVAC unit.
Most cars hold between 28 and 32 ounces of refrigerant (or about 2—3 12oz cans), however larger vehicles and those with rear A/C will likely hold more. Check your vehicle manual for the system capacity for your specific vehicle.
Look for the refrigerant level gauge. The gauge is usually on the side of the AC unit.
R-22 refrigerant prices range from $90 to $250 per pound. Since you'll need between 6 and 12 pounds to refill a home AC, costs can reach between $660 and $2,400 for a refill of R-22 refrigerant.
Under EPA regulations, only a certified professional can recharge your home's HVAC system.
A three-ton air conditioner would typically have six to 12 pounds of refrigerant for a proper charge. During the installation of a central air conditioning system, technicians carefully measure the refrigerant level and test the system.
Theoretically, Freon can last forever. It is not burned up like fuel. When an air conditioning system is in top shape, the refrigerant will be continually recycled within a closed system, to cool your home. However, as the AC tubing ages and wears out, it tends to develop leaks in the system.
Steps to Check Refrigerant Levels
Turn off the air conditioner and locate the service valves. Attach the manifold gauge set to the service valves. Turn on the air conditioner and observe the pressure readings, which should be between 30-40 PSI for most systems (though some may require higher or lower pressures).
Most ACs nowadays come shipped from the manufacturer with the exact amount of refrigerant that it will need for the duration of its life. So, unlike a car, your AC won't ever need to “fill up” on refrigerant unless something goes wrong with the system.
Your desired suction pressure is 33-48 degrees or 58-80 psi depending on the indoor temperature. (Note: The hot or warm air from a hot house traveling across the evaporator coil will warm the refrigerant faster than normal causing a higher suction pressure.
You also don't want to buy a model that's too powerful for a room. Sure, a 12,000-BTU air conditioner will cool a small space (150 square feet or less) quickly. But it might cool it too quickly, preventing it from removing some of the ambient humidity from the room and leaving the room damp.
This sounds too simple, but, it will feel empty. Shake the can or strike it with your fingernail. If it feels like it's empty, it is.
The correct amount of refrigerant lets the AC system cool your air correctly and efficiently, maintaining the correct pressure levels and system functions. Too much refrigerant leads to an overcharged air conditioner, which can reduce your unit's efficiency and cause several other problems for your system.
Weighing in at a 14.7 grams per can, you will need 32 cans per pound.