Roof-mounted air conditioner system having modular evaporator and condensor units

In an air conditioner system mounted on the roof of a bus, in which the bus is characterized by having an upper relatively flat roof, a ceiling spaced beneath said roof with a return air inlet disposed in said roof intermediately between air circulating ducts, said ducts extending between said roof and ceiling for directing conditioned air into the interior of said bus, there being compressor means to draw refrigerant from evaporator coils and to discharge said refrigerant under pressure, and a condensor unit including condensor coils to receive refrigerant under pressure from said compressor means, and air circulating means for directing air across said condensor coils, the improvement comprising:

• a modular evaporator unit having an outer shallow, generally rectangular housing including mutually opposed sidewalls and front and rear end walls and a base panel conforming to the contour of said roof including means for attaching said base panel to said roof whereby said return air inlet and said air circulating ducts are in communication with the interior of said evaporator housing, said evaporator coils mounted on opposite sides of said return air inlet, and heater coils extending horizontally in side-by-side relation to each of said evaporator coils on opposite sides of said return air inlet, a fresh air inlet in said rear wall of said evaporator housing, and evaporator air blower means in said evaporator housing for inducing air through said return air inlet and said fresh air inlet across said evaporator coils and heater coils for discharge through said air circulating ducts into the interior of said bus;
• refrigerant lines extending between said condensor unit and said evaporator unit;
• and
• said evaporator unit including damper means to regulate the ratio of return air and fresh air induced to flow through said respective return air and fresh air outlets, said damper means including inside temperature sensing means adjacent said return air inlet and outside temperature sensing means adjacent said fresh air inlet, said damper means responsive to the temperatures sensed at said return air inlet and said fresh air inlet to regulate the ratio of return air to fresh air drawn into said evaporator housing.