Vented vs unvented crawl space
I don't live in a hot climate, but I do know one thing, heat rises and cold falls. i can't understand the justification of putting AC into a crawl space that is not air tight.  I answered your question a long time ago about insulating and venting the crawl, and I still stand by that advise. I can not believe the air conditioning a dirt floor crawl space is going to positively effect the temp in the house above by any measurable amount. I think it will a waste of energy and money to AC the crawl.  I COULD BE WRONG, but I'd love to hear a compelling argument for doing it.