83OperationUnit operations should be controlled withthermostat, or unit controller, never at themain power supply, except for servicing,emergency, or complete shutdown of theunit.Thermostat OperationThermostat system switch - "Heat"HeatingThermostat fan switch - "Auto" or "On"Thermostat temperature set to desired point.Thermostat system switch - "Cool"CoolingThermostat fan switch - "Auto" or "On"Thermostat temperature set to desired point.Thermostat system switch - "Off"Air CirculationThermostat fan switch - "Auto" or "On"No change of the thermostat temperature.With these settings, the supply blower willrun continuously but the supply air will notbe heated, cooled, or dehumidified.Thermostat system switch - "Off"System OffThermostat fan switch - "Auto"No change of the thermostat temperature.With these settings the system is shut down,with the exception of control system power.To reduce the operating time of the unitwhen the space is unoccupied, such as nightsand weekends, it is recommended that thetemperature setting be raised about 5°Fwhile unoccupied during the cooling seasonand lowered about 10°F during the heatingseason.Night and Weekend Unoccupied OperationPackaged DX Cooling Operation andControlWhen a call for cooling (G and Y1, Y2, etc.)is made the supply blower motors andcompressors will energize.Gas Heater OperationWhen heat (G and W1, W2, etc.) is calledfor the combustion motor starts and theignition control is energized. The controlsends 24 VAC to the main gas valve andhigh voltage to the igniter. If a burner flamehas been detected within 10 seconds, thespark is extinguished and the flamecontinues. If a flame has not been detectedafter 10 seconds, the gas valve closes, thespark ceases and the induced draft blowercontinues to purge the heat exchanger. After45 seconds of purge, the ignition system willattempt to light the burners again. Should noflame be detected after 3 tries, the ignitioncontrol will lock out the system. Power tothe ignition control must be cycled to resetthe heater control.On a fault the gas train is shut down by amain limit located in the heat exchanger areaCOMPRESSOR CYCLING5 MINUTE MINIMUM OFF TIMETo prevent motor overheatingcompressors must cycle off for aminimum of 5 minutes.5 MINUTE MINIMUM ON TIMETo maintain the proper oil levelcompressors must cycle on for aminimum of 5 minutes.The cycle rate must not exceed 6starts per hour.WARNING
