Carrier 50PG20-28 Controls, Start-up, Operation, Service And Troubleshooting Instructions

Also see for 48PG20---28: User's information manual User's information manual Installation and service instructions

Carrier 50PG20-28 Controls, Start-up, Operation, Service And Troubleshooting Instructions Manual pdf 6 page image

START-UPUse the t'ollowing information and Start-Up Checklist onpage CL-1 to check out unit PRIOR to start-up.Unit Preparation -- Check that unit Ms been installed inaccor&mce with these installation instructions and all applica-ble codes.Compressor Mounting- Compressors are internallyspring mounted. Do not loosen or remove compressor hold-down bolts.Refrigerant Service Ports -- Each independent re-ft-igerant system has a total of 3 Schrader-type service gageports per circuit. One port is located on the suction line, one onthe compressor dischaNe line, and one on the liquid line. Besure that caps on the ports are ti_lt.Crankcase Heater(s)- Craalkcase heaters are ener-gized as long as there is power to the unit and the compressor isnot operating.IMPORTANT: Unit power must be on for 24 hours prior Ito start-up. Otherwise, damage to compressor mayIresult.Compressor Rotationhnproper wiring wilt cause compressor stoppage and alarm.Correct wiring by switching leads as indicated below.It is important to be certain the compressors are rotating inthe proper direction. To determine whether or not compressorsare rotating in the proper direction, use a phase-rotation meteron the unit input power to check tbr L1-L2-L3 or cloclcwise ro-tation or use the Service Test mode to energize a compressor. Ifthe compressor is rotating in the wrong direction, the controlswill stop the compressor and display alarm for "Circuit x Fail-ure to Pressurize," where x is the corresponding A or B com-pressor circuit.NOTE: Indoor or outdoor thn rotation direction may not indi-cate proper input power phase sequence, as some 3-phase unitsuse single-phase tan motors.To correct the wrong compressor rotation direction, performthe following procedure:1. Turn offpower to the unit and lock out the power.2. Switch any two of the incoming unit power leads.3. Turn on power to the unit.4. Verii_ corrected compressor rotation.Internal Wiring--Check all electrical connections inunit control boxes; tighten as required.Subcooler Heat Exchanger (SHX) -- The subcool-er heat exchanger adds approximately 10 to 15° F of sub-cooling to the system. Check all valves aald TXMEvaporator Fan- Fan belt and variable pulleys arefactory-installed. See Tables 3-26 for tan performance data. Besure that fans rotate in the proper direction. See Tables 27 and28 for air quantity limits. See Tables 29 and 30 for evaporatortan motor specifications. See Tables 31 and 32 for accessoryFIOP static pressure. See Tables 33 and 34 for tan rpm atvarious motor pulley settings. To alter tan performance, seeEvaporator Fan Performance Adjustment section on page 87.Condenser Fans and Motors -- Condenser thns andmotors are factory set. Refer to Condenser-Fan Adjustmentsection (page 88) as required.Return-Air Filters -- Check that correct filters are in-stalled in filter tracks (see Physical Data table in InstallationInstructions). Do not operate unit without return-air filters.NOTE: For units with 4-in. filter option, units are shipped withstandard 2-in. filters. To install 4-in. filters, the filter spacersmust be removed.Outdoor-Air Inlet Screens --Outdoor-air inlet screensmust be in place before operating unit.Gas Heat (48PG Only) -- Veril_ gas pressures beforeturning on heat as follows:1. Turn off field-supplied manual gas stop, located externalto unit.2. Connect pressure gage to supply gas tap, located on field-supplied manual shutoffvalve (see Fig. 4).3. Connect pressure gage to manifold pressure tap.4. Turn on field-supplied manual gas stop. Enter ServiceTest mode by setting TEST to "YES" using the ScrollingMarquee display. Temporarily install the jumper wirebetween "R" and "WI" on TB2. Use the Sin:ice Testfeature to set HT. 1 to ON (first stage of hea 0 using theScrolling Marquee.5. After the unit has mn for several minutes, veri_ the sup-ply gas press_ureis between 5.5 in. wg to 13.0 in. wg, andthe manitbld pressure is 2.95 in. wg on horizontal dis-charge applications and 3.00 on vertical dischaige appli-cations. If manifold pressure must be adjusted, refer toGas _alve Adjustment section.NOTE: Supply gas pressure must not exceed 13.0 in. wg.6. Set HT. 1to OFF using Scrolling Marquee.7. Remove jumper wire if the unit will be operating underthermostat mode. The jumper must remain if a space tem-perature sensor (T-55, T-56, or T-58) wilt control the unit.8. Exit Service Test mode by setting TEST to "NO" usingthe Scrolling Marquee.MANUALSHUTOFF(FIELD SUP_ GASPRESSURE TAP(1/8" NPT PLUG)Fig. 4-- Field Gas Piping