first speed in a second mode and a third speed lower than the second speed in a ventilation mode application_number US 201314371784 A description shown in fig1 is a typical packaged rooftop air conditioner having a condenser section 11 an evaporator section 12 and an economizer section 13 the condenser section 11 includes a compressor 14 for receiving refrigerant vapor from the evaporator section 12 and compressing the vapor before it is condensed also included in the condenser section 11 is a condenser coil 16 and a condenser fan 17 for passing ambient air through the condenser coil 16 the evaporator section 12 includes a supply fan 18 which is driven by a fan motor 19 the fan motor 19 is adapted to operate at variable speeds to meet the cooling heating requirements of the system and provide ventilation as described in further detail herein a heater 23 is placed in a downstream position from the supply fan 18 leading into the evaporator section 12 from the economizer section 13 is a cooling coil 21 and its associated filters 22 in operation the supply fan 18 draws air in through the filter 22 and the cooling coil 21 where it is cooled by refrigerant passing through the cooling coil 21 the cooled air then passes to the supply air duct 24 from which it is distributed within the building alternatively in the heating mode the air is passed from the supply fan 18 through the heater 23 where it is heated prior to being passed.