 Deborah McCoy has diabetes, which makes her especially sensitive to excess heat. A federally funded nonprofit helped her install central air conditioning this year at her home in Macon, Mississippi. It's a big improvement from her old window unit, but running the AC costs McCoy, who's on disability, about $200 a month. The next few days is going to be hot, hot, hot here, and I'm probably going to have to run around the clock.