Carrier SINGLE PACKAGE ROOFTOP UNITS ELECTRIC COOLING/GAS HEATING 48EJ Installation And Service Instructions Manual

Also see for 48EJ: Installation, Start-Up and Service Instructions User manual

Contents

START-UPUse the following information and Start-Up Checkliston page CL-1 to check out unit PRIOR to start-up.Unit Preparation — Check that unit has been installedin accordance with these installation instructions and appli-cable codes.Compressor Mounting — Loosen the compressor hold-down bolts until sidewise movement of the washer undereach holddown bolt head can be obtained. Do not loosencompletely as bolts are self-locking and will maintainadjustment.Service Valves — Ensure that the suction, discharge,and liquid line service valves are open. Damage to the com-pressor could result if they are left closed.Internal Wiring — Check all electrical connections inunit control boxes; tighten as required.Refrigerant Service Ports — Each refrigerant sys-tem has one suction port located in the top of the compressormotor casing. All units also have one service port on the liq-uid line valve and one on the compressor discharge valve.Be sure that caps on the ports are tight.Crankcase Heaters — Crankcase heaters are ener-gized as long as there is power to the unit, except when thecompressors are operating.IMPORTANT: Unit power must be on for 24 hoursprior to start-up. Otherwise, damage to compressor mayresult.Variable Frequency Drive (VFD) — The variablefrequency drives are factory set. These settings include factory-installed jumpers and software configurations. The onlyfield configured set point is duct static pressure. An Opera-tion Manual is shipped with each VAV unit. This manual shouldbe used if the drive needs to be customized for a particularapplication.NOTE: The VFD will always provide the proper phasesequence to the indoor-fan motor. The indoor-fan motor op-erates in proper rotation regardless of the phase sequence tothe unit. If, upon start-up, the outdoor fans operate back-wards but the indoor fan operates in the correct direction,reverse any two leads to the main terminal block. All fanswill then operate in the correct direction.To set the duct static pressure, perform the following steps.The factory setting is zero. The duct transducer has a rangefrom 0 to 5 in. wg. The transducer output is 4 to 20 mA,therefore, 0 to 5 in. wg is proportional to the 4 to 20 mA andmust be expressed to the VFD in terms of percentage of thefrequency range. Refer to Table 7. The set point value is apercentage of the maximum output frequency. Locate the ductstatic pressure closest to that desired and use the correspond-ing set point value. If necessary, interpolation between ductstatic pressures is permissible.Fig. 40A — Motormaster III Sensor Location(Sizes 024-034)Fig. 40B — MotormasterT III Sensor Location(Sizes 038 and 044)Fig. 40C — Motormaster III Sensor Location(Size 048)31