Carrier 50TC*17 Series Service And Maintenance Instructions

50Return−Air FiltersEnsure correct filters are installed in unit (see Appendix II− Physical Data). Do not operate unit without return−airfilters.Outdoor−Air Inlet ScreensOutdoor−air inlet screen must be in place before operatingunit.Compressor MountingCompressors are internally spring mounted. Do not loosenor remove compressor hold down bolts.Internal WiringCheck all electrical connections in unit control boxes.Tighten as required.Refrigerant Service PortsEach unit system has two 1/4” SAE flare (with checkvalves) service ports: one on the suction line, and one onthe compressor discharge line. Be sure that caps on theports are tight.Compressor RotationEQUIPMENT DAMAGE HAZARDFailure to follow this CAUTION could result inequipment damage.Scroll compressors can only compress refrigerant ifrotating in the right direction. Reverse rotation forextended times can result in internal damage to thecompressor. Scroll compressors are sealed units andcannot be repaired on−site.CAUTIONNOTE: When the compressor is rotating in the wrongdirection, the unit will make an elevated level of noiseand will not provide cooling.On 3−phase units with scroll compressors, it is importantto be certain compressor is rotating in the properdirection. To determine whether or not compressor isrotating in the proper direction:1. Connect service gauges to suction and discharge pres-sure fittings.2. Energize the compressor.3. The suction pressure should drop and the dischargepressure should rise, as is normal on any start−up.If the suction pressure does not drop and the dischargepressure does not rise to normal levels:1. Note that the evaporator fan is probably also rotatingin the wrong direction.2. Turn off power to the unit and install lockout tag.3. Reverse any two of the unit power leads.4. Reapply electrical power to the compressor.5. The suction pressure should drop, and the dischargepressure should rise, which is normal for scroll com-pressors on start−up.6. Replace the compressor if suction/discharge pressuresare not within specifications for the specific compres-sor.CoolingSet space thermostat to OFF position. To start unit, turn onmain power supply. Set system selector switch at COOLposition and fan switch at AUTO. position. Adjustthermostat to a setting below room temperature.Compressor starts on closure of contactor.Check unit charge. Refer to Refrigerant Charge section.Reset thermostat at a position above room temperature.Compressor will shut off. Evaporator fan will shut offafter a 30−second delay.To shut off unit, set system selector switch at OFFposition. Resetting thermostat at a position above roomtemperature shuts unit off temporarily until spacetemperature exceeds thermostat setting.NOTE: The default value for the evaporator−fan motoron/off delay is 45 seconds. The Integrated Gas UnitController (IGC) modifies this value when abnormal limitswitch cycles occur. Based upon unit operating conditions,the on delay can be reduced to 0 seconds and the off delaycan be extended to 180 seconds. When one flash of theLED is observed, the evaporator−fan on/off delay hasbeen modified.Ventilation (Continuous Fan)Set fan and system selector switches at ON and OFFpositions, respectively. Evaporator fan operatescontinuously to provide constant air circulation. When theevaporator−fan selector switch is turned to the OFFposition, there is a 30−second delay before the fan turnsoff.START−UP, PREMIERLINK CONTROLSELECTRICAL OPERATION HAZARDFailure to follow this warning could result in personalinjury or death.The unit must be electrically grounded in accordancewith local codes and NEC ANSI/NFPA 70 (AmericanNational Standards Institute/National Fire ProtectionAssociation.)! WARNINGUse the Carrier network communication software to startup and configure the PremierLink controller.Changes can be made using the ComfortWORKSsoftware, ComfortVIEW software, Network ServiceTool, System Pilot device, or Touch Pilot device. TheSystem Pilot and Touch Pilot are portable interfacedevices that allow the user to change system set−up andsetpoints from a zone sensor or terminal control module.During start−up, the Carrier software can also be used toverify communication with PremierLink controller.