The chassis air on older coaches didn't keep the whole big house cool when they worked at max output. I have had 3 older coaches, including the one I have now and just run the genny and house air when traveling. You can spend $2000+ fixing the dash air and you still won't keep the house cool when temp gets above 80. If all else is good don't let the non-functioning dash air stop you.
By the way, we have friends in the Lake Charles area and we like your town.
"96" HR Navigator, 38' no slides, Cummins, Allison