I would replace it. I live just outside of Houston, and here we have one of the largest, and least expensive, RV parts houses in the country.
PPL RV Parts.
Bought a ducted 13,500 upper and lower unit from them last month for, after taxes, just under $600.
I believe they ship anywhere in the country for a very reasonable rate.
Installing a rooftop is remarkably easy, biggest job is getting old one to ground and new one to roof. I'm lucky there, we have a tractor with front-end loader that handles it quite easily. I have seen 2 men take a unit up ladders and didn't seem too bad. Hooking up is no challenge even for an amateur.
I personally would not spend several hundred dollars with a A/C tech when I can get the whole package for around $600.
