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 92 page image

Filter Drier -- Replace whenever ref-igerant system is ex-posed to atmosphere. Only use factory specified liquid-linetilter driers with working pressures no less than 650 psig. Donot install a suction-line ftter drier in liquid line. A liquid-lineflter drier designed for use with Puron,_R)refi-igerant is requiredfor ca& circuit.Protective DevicesCOMPRESSOR PROTECTIONOvercu_rrent Each compressor has internal line break motorprotection.Overtemperature Each compressor has an intemal protectorto protect it against excessively high dischmge gas temperatures.Hi_h-Pressure Switch If the high-pressure switch trips, thecompressor will shut down and the currem sensor will notdetect current. See the Current Sensor section below for moreinformation.Current Sensor (CS) The purpose of the CS is to detectlosses in compressor power. After detecting a loss in compres-sor power, unit control locks out the compressor for 15 min-utes. After 15 minutes, the alarm will automatically reset. Ifthis atann occurs 3 times consecutively, the compressor will re-main locked out until an alarm reset is initiated via CCN ormanually via the Scrolling Marquee display (see Atanns andAlerts section on page 54 for more details).EVAPORATOR FAN MOTOR PROTECTION A manu-at reset, calibrated trip, magnetic circuit breaker protectsagainst overcurrent. Do not bypass connections or increase thesize of the breaker to correct trouble. Determine the cause andcorrect it before resetting the breaker.CONDENSER-FAN MOTOR PROTECTION Eachcondenser-fro1 motor is internally protected againstovertemperature.Fuses are also located in the control box and teed power tothe condenser fan motors. Always replace blown fuses with thecorrect size fuse as indicated on the unit fuse label.SATURATED SUCTION PRESSURE (SSP) If the SSPfor a particular circuit is reading below the alarm set point foran extended period of time, that circuit wilt be shut down. After15 minutes, the atann will automatically reset. If this alarmoccurs 3 times consecutively, the circuit will remain locked outuntil an alarm reset is initiated via CCN or manually via theScrolling Marquee display (see Alarms and Alerts section onpage 54 for more details).Relief Devices -- All units have relief devices to protectagainst d,'unage tiom excessNe pressures (i.e., fire). Thesedevices protect the high and low side and are located at the suc-tion line service port. Protect joint during brazing operationsnear joint.Control Circuit, 24-V- Each control circuit is pro-tected against overcurrent by a 3.2 amp circuit breaker.Breaker can be reset. If it trips, determine cause of troublebel\)re resetting.Replacement Parts -- A complete list of replacementparts may be obtained tiom any Carrier distributor uponrequest.Diagnostic LEDs -- The IGC control board Ms a LEDfor diagnostic purposes. See Heating Troubleshooting sectionon page 60 for more information.92