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I. Shut off power to unit. ------ J. Replace outdoor fan motor lead and turn on power. Heating SERVICE PORT SERVICE VALVE / ::_I P.EVERSIN6 VAL'!E OPERATION -GENERAL EXPLANATION AND GUIDANCE ACCUMULATOR The heat pump is a relatively simple device. It operates exactly as a Summer Air Conditioning unit when it is on the cooling I cycle.Therefore,all the charts and data for service that apply to COMPRESSOR summer air conditioning apply to the heat pump when it is on the cooling cycle, and most apply on the heating cycle except that"condenser"becomes"evaporator","evaporator"becomes PCATTlcc o "condenser" and "cooling" becomes "heating". o —S(RVI"Poor When the heat pump is on the heating cycle, it is necessary or to redirect the refrigerant flow through the refrigerant circuit NDOOR 0isrgv. OR ORIFICE CO,LI CMECKVALVE SERVICE VALVE CMECKVALVE ORIFICE 4 TDOOR UT COtL external to the compressor. This is accomplished with a HEATING DISTRIMTOR reversing valve. Thus, the hot discharge vapor from the compressor is directed to the inside coil (evaporator on the cooling cycle) where the heat is removed, and the vapor In addition to a reversing valve, a heat pump is equipped condenses into liquid. It then goes through a capillary tube,or with an expansion device and check valve for the inside coil, expansion valve, to the outside coil (condenser on the cooling and similar equipment for the outside coil. It is also provided cycle)where the liquid is evaporated, and vapor goes to the with a defrost control system. compressor. When the solenoid valve is operated either from heating to The expansion device performs the same function on the cooling or vice versa, it moves the pilot valve, thus putting heating cycle as on the cooling cycle.The check valves are suction pressure (low pressure) on one side of the piston of required due to the reverse flow of refrigerant when chang- the reversing valve,and since discharge pressure (high pres- ing from cooling to heating or vice versa. sure)is on the other side of the piston,the piston slides to the When the heat pump is on the heating cycle, at which time low pressure side and reverses the flow of the refrigerant in the outdoorcoil isfunctioning as an evaporator,the tempera- the circuit. ture of the refrigerant in the outdoor coil must be below the temperature of the outdoor air in order for the refrigerant in The following figures show a schematic of a heat pump on the outdoor coil to extract heat from the air.Thus,the greater the cooling cycle and the heating cycle. the difference in outdoor temperature and outdoor coil temperature, the greater the heating capacity of the heat Heat Pump Refrigerant Circuit pump. Since this is characteristic of heat pumps, it is good -- practice to provide supplementary heat for all heat pump I Cooling III RVICIPORT installations in areas where the temperature drops below SIRVICeVALVIE / R£VERSI%GVALVE 7.2°C. It is also good practice to provide sufficient supple- / mentary heat to handle the entire heating requirements if f there should be a failure of heat pump,such as a compressor SERVICE PORT ACCUMULATOR failure, or refrigerant leak, etc. I Since the temperature of the liquid refrigerant in the outdoor coil COMPRESSOR on the heating cycle is generally below the freezing point,frost forms on the surfaces of the outdoor coil under certain U weather conditions of temperature and relative humidity, n EZPAnSIONOEVICE P�TCE N Therefore, it is necessary to reverse the flow of the refriger- g —SERVICE PORT ant to provide hot gas in the outdoor coil to melt the frost accumulation. This is accomplished by reversing the heat OUrT m to the cooling I .A h m time, h outdoor n INDOOR COIL I �wtfa V•\Vf SE RwCE lALVE CMECKVALVE OAIfICE caa pump e coo g cycle. t the same e,the ou doo a DISTRIBUTOR stops to hasten the temperature rise of the outdoor coil and COOLING lessen the time required for defrosting. The indoor blower continues to run and the supplementary heaters are ener- gized. SERVICE: The following information is for use by qualified service agency only; others should service this equipment. 10 Downloaded from www.Manualslib.com manuals search engine