Does the back part of a window AC have to be outside to work? If an air conditioning unit has been designed for mounting in a window, the back part must be outside in order for the unit to function properly. These air conditioner units are designed to vent hot air out of the back. The hot air produced by the air conditioner is the system's exhaust. If the hot air is not allowed to vent to the outside to dissipate, the heat it generates is likely to negate the work of the air conditioner. This overworks the air conditioner's condenser, which reduces the operating life of the unit, and it may also void the product warranty. To clean a window air conditioner, slide the unit out of its case, move it outside to work, and straighten any bent fins. Vacuum the coils, spray with air ... How does a thermostat go bad in a house? How many trucks are part of the Schneider trucking company? How do Goodman furnaces compare to other furnaces? What are some different types of soapstone wood burning stoves?