Carrier 50TC*17 Series Service And Maintenance Instructions

823. Install the motor drive V-belt to the motor pulley andblower wheel pulley. See CAUTION.24. Align the motor pulley and blower wheel pulley usinga straight edge. See Fig. 7.25. Adjust the V-belt tension using the adjustment tool.26. Turn the two jack bolts clockwise, moving the motorassembly away from the blower pulley, increasing theV-belt tension.27. Tighten the four bolts securing the motor mountingbrackets to the unit. Torque bolts to 120 ± 12 in-lbs(14 ± 1.4 Nm).28. Remove the cover on the motor connection box.29. Re-connect all electrical leads to the motor and replace the connection box cover.30. Re-connect all electrical power to the unit. Removelockout tags on all electrical power sources.31. Start the unit and allow to run for a designated period.32. Shut off the unit and make any necessary adjustmentsto the V-belt tension or the motor and blower wheelpulley alignment.BROWNING BELTTENSION CHECKERSTRAIGHTEDGE1/2”(1.3 cm)BELTDEFLECTIONC12093Fig. 11 − Adjusting V−belt TensionChanging Fan Wheel Speed by Changing PulleysThe horsepower rating of the belt is primarily dictated bythe pitch diameter of the smaller pulley in the drivesystem (typically the motor pulley in these units). Do notinstall a replacement motor pulley with a smaller pitchdiameter than provided on the original factory pulley.Change fan wheel speed by changing the fixed fan pulley(larger pitch diameter to reduce wheel speed, smallerpitch diameter to increase wheel speed) or select a newsystem with both pulleys and matching belt(s).Before changing pulleys to increase fan wheel speed,check the fan performance at the target speed and airflowrate to determine new motor loading (bhp). Use the fanperformance tables or use the Packaged Rooftop Buildersoftware program. Confirm that the motor in this unit iscapable of operating at the new operating condition. Fanshaft loading increases dramatically as wheel speed isincreased.EQUIPMENT DAMAGE HAZARDFailure to follow this CAUTION can result in equipmentdamage.Drive packages cannot be changed in the field. Forexample: a standard drive cannot be changed to a highstatic drive. This type of change will alter the unit’scertification and could require heavier wiring to supportthe higher amperage draw of the drive package.CAUTION!To reduce vibration, replace the motor’s adjustable pitchpulley with a fixed pitch pulley (after the final airflowbalance adjustment). This will reduce the amount ofvibration generated by the motor/belt-drive system.To determine variable pitch pulley diameter, perform thefollowing calculation:1. Determine full open and full closed pulley diameter.2. Subtract the full open diameter from the full closeddiameter.3. Divide that number by the number of pulley turnsopen from full closedThis number is the change in pitch datum per turnopen.EXAMPLE:– Pulley dimensions 2.9 to 3.9 (full close to full open)– 3.9 - 2.9 = 1– 1 divided by 5 (turns from full close to full open)– 0.2 change in pulley diameter per turn open– 2.9 + 0.2 = 3.1″ pulley diameter when pulley closedone turn from full openCONDENSER COIL SERVICEROUND TUBE PLATE FIN (RTPF)CONDENSER COILThe condenser coil is fabricated with round tube copperhairpins and plate fins of various materials and/or coatings(see the Model Number Nomenclature in Appendix 1 toidentify the materials provided in this unit). The coil maybe one−row or composite−type two−row. Compositetwo−row coils are two single−row coils fabricated with asingle return bend end tubesheet.Recommended Condenser Coil Maintenanceand CleaningRoutine cleaning of coil surfaces is essential to maintainproper operation of the unit. Elimination of contaminationand removal of harmful residues will greatly increase thelife of the coil and extend the life of the unit. Thefollowing maintenance and cleaning procedures arerecommended as part of the routine maintenance activitiesto extend the life of the coil.