You got a problem...and it is NOT the a/c. It is something BEFORE the a/c unit.
Low voltage is a prime suspect. Have the a/c fixed one more time...then go to Progressive Industries or an RV internet supplier (I've had great luck at Tweetys.com) and get their 30AMP unit. (I presume that is what you have...they also have 50 AMP units if you have 50AMP) And while you're at it....presumably at your RV dealer for the a/c, have them check out your entire electrical circuits. Make sure the CONverter is working OK...they do get "weak" but not after only 2 years, as far as I know. Mine got "weak" after 16 years...and, BTW, my 2 roof a/c units are original and work fine.