Carrier 50JZ024 Installation, Start-up And Service Instructions Manual

Also see for 50JZ024: Installation and operating instructions Guide to operating and maintaining Guide to operating and maintaining Product data Product data

Contents

1. Place room thermostat SYSTEM switch or MODE control inOFF position. Observe that blower motor starts when FANmode is placed in FAN ON position and shuts down within 60sec (030-060 size) or 30 sec (024 size) when FAN MODEswitch is placed in AUTO position.2. Place SYSTEM switch or MODE control in COOL positionand FAN mode in AUTO position. Set control below roomtemperature. Observe that cooling cycle shuts down whencontrol setting is satisfied.3. Place SYSTEM switch or MODE control in HEAT position.Set control above room temperature. Observe that compressor,outdoor fan, and indoor blower motors start. Observe thatheating cycle shuts down when control setting is satisfied.4. When using an automatic changeover room thermostat, placeboth SYSTEM or MODE control and FAN mode switches inAUTO positions. Observe that unit operates in Cooling modewhen temperature control is set to ‘‘call for Cooling’’ (belowroom temperature), and unit operates in Heating mode whentemperature control is set to "call for Heating" (above roomtemperature).IMPORTANT: Three-phase, scroll compressors are direction ori-ented. Unit must be checked to ensure proper compressor 3-phasepower lead orientation. If not corrected within 5 minutes, theinternal protector may shut off the compressor. The 3-phase powerleads to the unit must be reversed to correct rotation. When turningbackwards, the difference between compressor suction and dis-charge pressures may be dramatically lower than normal.CHECKING AND ADJUSTING REFRIGERANT CHARGE— The refrigerant system is fully charged with R-410A refriger-ant and is tested and factory sealed.NOTE: Adjustment of the refrigerant charge is not requiredunless the unit is suspected of not having the proper R-410Acharge. The charging label and the tables shown refer to systemtemperatures and pressures in cooling mode only. A refrigerantcharging label is attached to the outside of the service access door.If charge level is suspect in Heating mode, reclaim all refrigerantand charge to nameplate amount. (This information may beobtained from the physical data table also.)IMPORTANT: When evaluating the refrigerant charge, an indi-cated adjustment to the specified factory charge must always bevery minimal. If a substantial adjustment is indicated, an abnormalcondition exists somewhere in the cooling system, such as insuf-ficient airflow across either coil or both coils.REFRIGERANT CHARGE — The amount of refrigerant chargeis listed on the unit nameplate and /or the physical data table. Referto Carrier Refrigeration Service Techniques Manual, RefrigerantsSection.NO CHARGE — Check for leak. Use standard evacuating tech-niques. After evacuating system, weigh in the specified amount ofrefrigerant (refer to system data plate).LOW CHARGE COOLING — Use Cooling Charging Charts(Fig. 23-28). Vary refrigerant until the conditions of the chart aremet. Note that charging charts are different from type normallyused. Charts are based on charging the units to correct superheatfor the various operating conditions. Accurate pressure gauge andtemperature sensing devices are required. Connect the pressuregauge to the service port on the suction line. Mount the tempera-ture sensing device on the suction line and insulate it so that theoutdoor ambient does not effect the reading. Indoor air CFM mustbe within the normal operating range of the unit.TO USE COOLING CHARGING CHARTS — Take the outdoorambient temperature and read the suction pressure gauge. Refer tothe chart to determine what the suction temperature should be.NOTE: If the problem causing the inaccurate readings is arefrigerant leak, refer to Check for Refrigerant Leaks section.INDOOR AIRFLOW AND AIRFLOW ADJUSTMENTSFor heating and cooling operation, the recommended airflowis 350 to 450 cfm for each 12,000 Btuh of rated coolingcapacity. for units with optional electric heat, the airflow mustnot be reduced below the levels stated in Table 2.Table 4 shows both heating and cooling airflows at variousexternal static pressures. Refer to these tables to determine theairflow for the system being installed.NOTE: Be sure that all supply-and return-air grilles are open, freefrom obstructions, and adjusted properly.Airflow can be changed by changing the lead connection of theblower motor.Unit 50JZ three-speed motors (except size 030 and 048) arefactory wired for low speed operation. Unit 50JZ 030 and 048 arefactory wired for medium speed.For 208/230v Motors:—The motor leads are color-coded asfollows:3-SPEEDBlack = high speedBlue = medium speedRed = low speedTo change the speed of the blower motor (BM), remove the fanmotor speed leg lead from the blower relay (BR). This wire isattached to IGC terminal BM for single-phase and 3-phase units.To change the speed, remove and replace with lead for desiredblower motor speed. Insulate the removed lead to avoid contactwith chassis parts.For 460v GE Motors—The motor leads are color coded as follows:3-SPEEDBlack = highViolet = jumperOrange = mediumRed = lowTo change the speed of the blower motor (BM), remove fan motorspeed lead from the blower relay (BR) and replace with the leadfor the desired blower motor speed. The motor speed lead isattached to terminal BM. For low and medium speeds black mustbe connected to the jumper wire. Insulate removed lead end toavoid contact with chassis parts. To select high speed on 460v GEmotors, separate the black female quick connect (QC) from thejumper lead male quick connect (QC) and connect the black leadto the BR. Insulate the jumper to avoid contact with any chassisparts.Step 3—Defrost ControlQUIET SHIFT — Quiet Shift is a field-selectable defrost mode,which will eliminate occasional noise that could be heard at thestart of defrost cycle and restarting of heating cycle. It is selectedby placing DIP switch 3 (on defrost board) in ON position.When Quiet Shift switch is placed in ON position, and a defrost isinitiated, the following sequence of operation will occur. Revers-ing valve will energize, outdoor fan will turn off, compressor willturn off for 30 sec and then turn back on to complete defrost. Atthe start of heating after conclusion of defrost reversing valve willde-energize, compressor will turn off for another 30 sec, and theoutdoor fan will stay off for 40 sec, before starting in the heatingmode.16