I believe the salesman is trying to make you believe that because the AC is not working it's not worth it. I run my dash air all the time. If it gets hot I start the genny and one AC if necessary the 2nd AC. In any event I run the rear AC to cool down the heat in the bedroom.
Tony & Ruth........... FMCA#F416727
2016 London Aire 4519, Freightliner chassis, Cummins ISX, 2018 Jeep Wrangler Unlimited, Blue Ox Avail with AF1. TST 507 TPMS