To replace an air conditioner evaporator coil, disconnect the unit, examine it for damage, cut the tubing to remove the coil, and then insert the new coil into the port. The procedure for replacing an evaporator coil varies with the make and model of the air conditioner.
Disconnect the power supply to the unit, and examine the coil for damages or cracks to ascertain that it needs replacement. Remove the coil from the air conditioner. To remove a cracked coil, cut the inbound and exit tubes. The tubing must be cut in case the refrigerant leaked to the areas around the coil. Once you have removed the old coil from the unit, insert a new coil into the port previously occupied by the old coil, and secure the new coil in place with a silver solder.
After soldering the new coil, put a vacuum on the conditioner to eliminate air from the lines. If needed, charge or recharge the coolant to bring it to a proper level. Reconnect the power supply to the air conditioner. To test the new coil, switch on the unit by setting the thermostat to a cool mode, and then lower the thermostat to a desired temperature.