In a side ventilator, the air conditioner vents out of the side of the unit, as opposed to the rear of the unit. Thus, side ventilators generally should not be used with sleeves, and should be installed so that the ventilation grates are situated outside the house.
(In order to figure out how many BTU you will need to properly cool a room, multiply the square footage of the room by 25. Then add 1,000 for each window, and 400 for each occupant. Thus, if your room is 500 square feet and you have two windows and three occupants, the total BTU you will need is: (500 x 25) + (1,000 x 2) + (400 x 3) = 15,700 BTU.)
There are hundreds of options to choose from for a window or wall air conditioner from Rainbow Appliance. Find a window unit air conditioner or thru the wall air conditioner in any btu range, to fit any living space. Most are Energy Star efficient and many include both heating and cooling capabilities.