If your central AC equipment is over 10 years old, it might be losing efficiency and breaking down more often. There are circumstances where it makes more sense to replace your AC instead of paying for another repair: If its SEER rating is lower than 14-SEER, then upgrading to higher-efficiency equipment will pay off quickly with lower monthly bills. If your current system uses R-22 refrigerant, you should almost certainly replace it. R-22 refrigerant is environmentally harmful and has been discontinued. Finding R-22 and replacing parts for systems using it is expensive. You should replace your system if the cost of a repair is more than 50 percent of the cost of new equipment.