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

Step 11 — Install All Accessories — After all thefactory-installed options have been adjusted, install all field-installed accessories. Refer to the accessory installation in-structions included with each accessory.MOTORMASTERt III INSTALLATIONInstall Field-Fabricated Wind Baffles — Wind baffles mustbe field-fabricated for all units to ensure proper cooling cycleoperation at low-ambient temperatures. See Fig. 39 for baffledetails. Use 20-gage, galvanized sheet metal, or similarcorrosion-resistant metal for baffles. Use field-supplied screwsto attach baffles to unit. Screws should be 1⁄ 4-in. diameterand 5 ⁄8 -in. long. Holes for wind baffles are pre-punched inthe unit sheet metal.To avoid damage to the refrigerant coils and electricalcomponents, use recommended screw sizes only.On 48EJ,EK,EW,EY024-034 units, the wind baffles at-tach to flanges formed on the outer sheet metal of the unitwhere the condenser coil tube sheets attach.On 48EJ,EK,EW,EY038-048 units, the wind baffles at-tach to flanges formed on the outer sheet metal of the unitcorner post. The other end of the baffle is attached to thecenter panel between the condenser coil and the indoor sec-tion. Two baffles are required for 48EJ,EK,EW,EY038-048units.Install Motormaster III Controls — Only one MotormasterIII control is required per unit.Motor — The circuit no. 1 (lead compressor) outdoor-fanmotor (OFM) will need to be changed out in the field to ac-commodate the Motormaster III accessory. The replacementmotor part no. is HD52AK652.On 48EJ,EK,EW,EY038-048 units, only one OFM will needto be changed out. The no. 1 compressor is located at the leftside of the unit looking from the compressor end. The circuitno. 2 OFMs are controlled to shut off at 55 F and turn on at65 F outdoor-air temperature.Sensor — Install the sensor for thermistor input control inthe location shown in Fig. 40A-C. Connect sensor leads tothe violet and gray control signal leads on the MotormasterIII control.Signal Selection Switch — Remove the cover of the Motor-master III control. Set the switch to accept the thermistorsensor input signal. Set the frequency to match the unit powersupply (60 Hz).Motormaster III Control — The recommended mounting lo-cation is in the indoor fan section, mounted on the panel thatseparates the indoor and outdoor sections. On VAV units,this location is next to the VFD.Do not route the Motormaster III wiring next to the VFDon VAV units. Use a separate connector through the partitionwhen wiring to the OFM.Electrical ConnectionsTo avoid possibility of electrical shock and personal in-jury, turn off all power to unit before making electricalconnections.When replacing the OFM, reconnect the black, yellow, andblue wires form the outdoor fan contactor to the black, yel-low, and blue wires of the Motormaster III control. Run newwires from the red, orange, and brown wires to the leads ofthe new OFM. Connect the green wire from the control toground.NOTE: On all 575-v units, 2 transformers (part no.HT01AH851) must be used for each Motormaster III con-trol to lower the supply voltage to the control to 460-v. Trans-formers can be mounted anywhere outside the control box.VAV — Variable Air VolumeFig. 38 — Pressure Transducer Locations1877.71 BOTH SIDESCROSS-BREAK78.7 0.5614.6217.167BETWEENHOLES(TYPICAL)0.312 DIAHOLESNOTE: All dimensions are in inches. Material: 20 gage galvanizedsteel or other non-corrosive material.Fig. 39 — Motormaster III Baffle Details30