putting it on the roof is one way to get rid of the small noise that it makes, and for places with limited room. perferably the air conditioner should be on the shaded side of the house(during the heat of the day) to allow it to operate more efficiently to disperse the heat it generates.without the hot sun beating down on it.
the pump for the unit doesn't push air, just the refridgerant.
and air handlers that push the cool air get put in the attic or crawl space for ease of a retrofit installation.