Over the life of an AC system, you may have to add refrigerant to it once. However, adding refrigerant a second time, especially in a short span of time, could mean you have a leak. The refrigerant circuit of an air conditioning system is a closed circuit which means refrigerant should not be lost or gained. Leaks need to be addressed or you will lose functionality, the system will freeze up, and cause damage to other parts of the system like the compressor. Using several different techniques and tools (the most common is an electronic leak detector) the technician will first look for a leak in the evaporator coil. This is the coil inside your house and is the most common area for a refrigerant leak to occur. What to do next once you hear the news?
Depending on the age and type of refrigerant the system uses, you will need to decide on repair vs. replacement. A good rule of thumb is if the system is over 10 years old and/or uses R-22 refrigerant you should consider replacement. If replacing the entire system is not something you are prepared for, then be prepared for the cost of a coil replacement.
Since the evaporator coil is the most common component to leak, we are going to use it for our pricing example. As already mentioned, the evaporator coil is the coil inside your home responsible for heat transfer. In addition to the cost of material (the coil itself, new filter drier, refrigerant, miscellaneous brazing material) it is a labor-intensive job. A high-level view of the process is as follows – remove remaining refrigerant from system, remove coil and filter drier, braze in new coil and filter drier, pressure test with nitrogen, vacuum system to remove moisture, and finally re-charge and test operation.
The average cost to replace a coil in a residential system is $3,000.