A common rule of thumb in the HVAC industry is that if your air conditioning unit is more than 8 years old, it may be more beneficial to replace the entire unit rather than a single component. This is because air conditioners have an expected lifespan of around 10 to 15 years. The main components of an air conditioning system include the condenser, evaporator coil, compressor, and fan. The thermostat and ducts are also technically part of the system.
The refrigerant circulates continuously to remove heat from your home until the indoor air temperature reaches the one you chose on the thermostat. For example, if you have a 12 SEER unit that needs to replace the evaporator coil, it's quite possible that the replacement 12 SEER coils for that model are obsolete and no longer being manufactured. In this case, you'll need to at least replace the condensing unit and the attic evaporator coil to convert them into the new refrigerant. In many cases, replacing the evaporator coil means that it no longer matches the condenser (the outdoor unit) in terms of age, SEER rating (the degree of efficiency of the air conditioner), or type of refrigerant.
Most air conditioners worth their price have an average lifespan of between 10 and 15 years, with adequate and regular maintenance of 26%. A good rule of thumb is that if your air conditioner is nearing the end of its life and if repairs cost more than 50% of the cost of the air conditioner itself, it's time to replace it. However, in warm places where air conditioners are used almost all year round, their lifespan is much shorter. If your unit uses R-22, the best option is to replace the entire unit with one that uses a new generation of environmentally friendly, affordable refrigerant called R-410A. If your system is more than 10 years old and your condenser or compressor isn't working outside, you'll have to deal with an expensive replacement.
Even so, there is something to be said when replacing a very old unit, when choosing to replace the entire system. During a normal cooling cycle, the fan draws warm air from inside the house and blows it onto these small copper tubes. Suppose you have a system that is only 4 or 5 years old and the outdoor unit is damaged, you can replace it with another of the same type. The air conditioner coil, or evaporator coil, of your air conditioning system is one of its most important components. Contact a professional HVAC technician to help you evaluate costs and replacement options.