Will my air conditioner unit cool my whole house? Jessica 24 November 2021 13:38 Updated An air conditioner will only cool down the room it is placed in. Related articles What size air conditioner shall I get? How often do I need to drain the water tank? Does my air conditioner unit double up as a heater in the winter? Can I use a portable air conditioner in a room without a window? What size is the window kit?