After 1 year we swapped out at 13,500 for a 15,000 (35 foot trailer with 3 slides). Yes, it made a big difference!
If you get the right replacement, you can just replace them with no problem. It needs to match the wiring plugs (everything is just plug in, no single splicing wires at all). It needs to match the design of the plenum (the part that you see inside your camper on the ceiling that hold the filter). And it needs to match your air flow, meaning duct work. You will not need to change the thermostat on your wall. If you get the same one you currently have, just the 15,000 btu version, you'll have no problems swapping them
I strongly suggest you check with your original dealer's repair shop service specialists to get the right model that matches your existing air conditioner. You don't necessarily have to purchase through them, but they could give you the model number, their price, and their price to install it. After you get all the information give them a wonderful "Thank-you" and you'll need to think about it and talk to the "wife" first about the cost. (That's your escape out of there making no commitments), but now, you've got the information.
You can then either use their services, or use someone elses, or do the work yourself.
But to answer your original question, if you get the right match, there is nothing special to do. Just pull the old one, drop in the new one, attach the wires and you're good to go.
