You won't get reimbursed for you travel expenses. Had you called a mobile RV repair guy and had the a/c repaired you may have gotten that reimbursed from the mfr.
Either:
1. The a/c never worked, it was a cool day in Sept when you did the pdi and it was just blowing air but felt like it was working;
2. The a/c developed a mysterious slow leak over the winter and now has no refrigerant left in it;
3. The CG had low voltage at the pedestal so the fan aould come on but the compressor wouldn't start;
4. There was a problem with the 12v control circuit to the t-stat.
Not sure if you asked, but I would have seen if my neighbors were having a/c problems, and also asked around to see if anybody could lend some diagnostic help. At a minimum, ask to borrow a multi-meter, odds are good that somebody in the CG would have one.
Last resort, call the mobile RV tech. Let's see, 5 1/2 hour drive each way, that's 11 hours total @ an average 50 mph = 550 miles, @ at 10 mpg = 55 gals, @ $4.00/gallon = $220 in fuel with no vacation to show for it...
I would have driven to Wal*Mart and bought a small a/c for $99 before I would have cancelled the trip. Just my $.02.