2004 jeep grand cherokee larado

First the mechanic has to "blow down" the old system to recycle it. Then he has to replace the part (expansion valve) and then recharge the system. It will take a few hours, but giving a cost is hard because he might have "environmental fees" that he has to charge for the "capture and recycling" of the old Freon and new Freon. If you are going to have him "open up the system" have him also replace the "inline screen filter" that is inside the condenser tube at the connection with the condenser and the compressor line leading to it. High pressure gas is fed from the "Compressor" (belt run pump) to the "Condenser" (radiator looking thing in front of the engine radiator) were is converted into a high pressure liquid as it goes to the "Dryer", then it is fed as a high pressure liquid into the "Expansion Valve". Leaving the "Expansion Valve" as a low pressure liquid it is fed into the "Evaporator" (near the interior blower) where it becomes a low pressure gas as it passes thru the "Evaporator" on its way back to the Expansion Valve". From the "Expansion Valve" it is sent back to the "Compressor" as a low pressure gas to be recompressed and continue on.