Depending on your Ford Expedition or Lincoln Navigator model, you must get special tools to uncouple the refrigment lines at your air conditioning system. These different tools can find at regular auto parts stores to match the size of the piping. Before you can disconnect the air compressor, you need to get the vehicle to a dealership or automotive air conditioning shop to drain the system. Once there, you must also remove the negative battery terminal. Start by taking off the accessory drivebelts, put your vehicle securely on jackstands if you own an Expedition or Navigator, switch off the air suspension, and lift the car up. Before you take out the compressor, first scoop up all the refrigerant oil and then disconnect the 3 electrical connections and 2 refrigerant lines. Then, unfold the radiator's air plastic guard to get to the compressor, remove its mounting bolts, and lift off the compressor. When installing the new compressor, empty all shipping oil from it, then put back the same quantity of new oil as what you got from the old compressor. First undo all connections. Then slip new O-ring rings coated with fresh refrigerant oil onto the compressor as you reconnect the line block. Replace the orifice tube as well, possibly needing special tools to do so. Have a pro checkout, refresh, and test your system for leaks before you finish the installation.