What kind of AC unit do you have. I have the standard roof mounted Coleman AC. The air coming out of the vents was minimal to say the least. I took the inside cover off and found that much of the air coming from the AC was going right back up the return side due to poor installation. I also found the holes that were cut for the ducts were smaller than they could have been and enlarged them. And lastly, I noticed a lot of air escaping around the inside cover, corrected it.
Your situation may be different of course, but first check to see if you are losing air.
Tom Wilds
Blythewood, SC
2016 Newmar Baystar Sport 3004
2015 Jeep Wrangler 2dr HT