In the thread:
Try this first before you buy 2nd AC unit or bring your unit in for AC service.
You will see about placing a vent on the bottom face of your AC unit blowing into your cab...
This one 8.00 modification has made a world of difference in my VEGAS. On 90+ days now the coach is showing 74-78 degrees where before it was in the upper 80's.. Please don't dismiss this little modification (especially since it only takes a vent and a dremel)..