Measure the old unit, and find a new one that fits the same measurements. If it is larger, you will need a saw to make a larger hole.
Disconnect the ceiling portion of the air conditioner from inside. Return outside and climb up the ladder to the roof. Use caution.
Disconnect the roof portion of the air conditioner. Carefully scrape away the old sealant from the roof, and avoid scratching the roof.
Place the roof portion of the new unit into position, and secure with mounting bolts. Return inside the RV.
Install the bolts that hold the ceiling portion in place, and mount the ceiling unit with the screwdrivers. Secure it to the roof part of the unit.
Apply sealant between the roof and roof air conditioner portion.
Connect all of the wires, and plug the ceiling unit into the roof unit.
