My A/C was "broken" for the longest time. I found out the reason why was because a cable got shredded by rubbing against the alternator belt, which I thought was just a ground wire, turned out to be the wire to the A/C compressor. Fixed the wire and the A/C blows ice cold. It really makes you appreciate it when you go without it for so long. Now I use it like a luxury.
How about an "ice vest"? Read about it in the article that lead me to this site. Day before you take a trip, fill (almost fill) a life preserver jacket with water and toss it in a freezer. Will keep you nice and cool until the ice melts, which should take more than an hour.