The refrigerant must be evacuated and lines disconnected, as well as the engine coolant and heater hoses. The dash assembly must be removed to get to the heating and cooling unit. The heating & cooling unit must be removed and taken apart to access the evaporator to replace it. While in there, it may make sense to also replace the heater core, as well. It's a pretty big job for most DIY'ers. You can check a site like repairpal.com to get an idea of what the job costs in your area.is it hard to change the air condition evaporator core the mechanic want $2200 to chanege it its probably better to trade in for another vechile it only have 80000 miles