Who’s full of hot air? Mayor Bloomberg wants to maintain his politically correct credentials on global warming — but hates to get into a hot car when he leaves an air conditioned building. The solution his aides came up with could easily have doubled as a stunt on David Letterman’s show. In full view of bemused tourists and other passers-by, workers yesterday performed what looked like a comedy routine: They hoisted a standard room air conditioner to a side window of one of the mayor’s SUVs parked in the City Hall lot to see if it would fit... < snip...