In a time where they developed nuclear bombs, the presidents car had to be cooled using blocks of ice. Awkward....,(reply>), A/C as we know it today was still in it's infancy. I think it was invented in the 1920's (and fun fact, I live right near where the inventor of it used to live) and it didn't really catch on until the 50's when the tech actually got reliable enough to use,(reply>), Electrically powered AC was in it's infancy during this time.  Most AC for railcars, if not ice cooled, had a form of mechanical operation, and modern style refrigerants were unheard of.  Ammonia gas was the prevailing formula used.