If y'all don't mind, I'll try to help the OP...
I have an Alfa motorhome with a Coleman basement air conditioner/heat pump, and I have some experience getting it worked on. I do not have a Winnebago but probably the same or very similar Coleman.
OP, do you know what the HVAC guy did? Did he add freon, and if so, do you know how he determined it was necessary? Or did he do something else and tell you you're going to need freon soon? Your post isn't clear on that.
If he added freon, how did he do it? As others have noted, these units don't come with the port(s?) necessary to add freon. I've never heard of a vampire port, but when Alfa owners go to the trouble to have the unit removed to be worked on (which is necessary on an Alfa, and not cheap), the advice is to have a port (or ports?) brazed on, in order to be able to add freon in the future.
Or, I guess I should ask--what do you mean the air conditioner was "not working"? Wouldn't come on? Wouldn't put out cold air? Would come on and then turn itself off after a while?
Someone said these basement units aren't designed to be serviced, but replacement ones aren't available any more (the new ones have the ductwork reversed), so many Alfas have had theirs worked on and keep them running. The newest Alfa out there is a 2008, which means there are lots of air conditioners still running that are substantially older than the OP's. Like my 2003--replaced one of the compressors a couple of years ago, and it's working fine.
Can you be more specific about what was wrong and what was done to fix it?
