The air conditioning evaporator is the heat absorption unit in the air conditioning system. Warm air from the passenger compartment is drawn through the evaporator and cooled. Then the cool air is redirected to the interior of the vehicle. It also dehumidifies the air.
The most common failure of the evaporator is leakage cause by corrosion. Once the evaporator begins to leak, it can no longer cool the warm air and it will need replacing.
Most manufacturer's factory warranty cover the air conditioning evaporator under the bumper-to-bumper warranty, if it fails due to a manufacturer defect or workmanship. There are extended auto warranties available that will extend coverage of the air conditioning evaporator after the factory warranty has expired. When purchasing an extended warranty, make sure to look at which coverage level includes the evaporator.