In-dash air conditioner - Worth converting or fixing?

We do not use the dash AC we run the generator and the roof AC. Pull the curtains on the overhead and on HOT days close off the back end of the RV. We have a fan right behind the front seats to blow the air into the cab and have always been cool. We like it this way since it takes a huge heat load off of the engine and the back end is cool whenever we stop. Also when the boy is with us we would have to run the house AC for him so why run both.