Carrier WeatherMaker 48A2020 Controls, Start-up, Operation, Service And Troubleshooting Instructions

201APPENDIX F — OPTIONAL FACTORY-INSTALLED LOW AMBIENT MOTORMASTER® V CONTROL (cont)When a compressor has been commanded on, then Motormas-ter Fan Circuit A (SCB Relay 1) will be energized (MM.F.A =ON). Motormaster Fan Circuit A will remain on until all com-pressors have been commanded off. If the highest active circuitSCT is above the HPSP or if OAT is greater than 75°F thencondenser fan B (MBB Relay 5) will be energized (CD.F.B =ON). Condenser fan B will remain on until all compressorshave been commanded off, or the highest active circuit SCTdrops 40°F below the HPSP for greater than 2 minutes andOAT is less than 73°F.NOTE: For size 60 units with RTPF condenser heat exchangersnot configured for Motormaster control, the control stages downdifferently than the other units. For these units, the control willfirst turn off condenser fan relay A. After 2 minutes, the controlwill turn off relay B and turn back on relay A.For 48/50A060 size units with MCHX condensers, there arefour outdoor fans, two for each independent refrigerant circuit.The control cycles two stages of outdoor fans for each circuit,one fan per stage, to maintain acceptable head pressure.When a circuit A compressor has been commanded on, then Mo-tormaster Fan Circuit A (SCB Relay 1) will be energized(MM.F.A = ON). Motormaster Fan Circuit A will remain on untilall compressors have been commanded off. If SCTA is above theHPSP or if OAT is greater than 75°F, then condenser fan A (MBBRelay 6) will be energized (CD.F.A = ON) turning on OFC4. Con-denser fan A will remain on until all compressors have been com-manded off, or SCTA drops 40°F below the HPSP for greater than2 minutes and OAT is less than 73°F.When a circuit B compressor has been commanded on, thenMotormaster Fan Circuit B (SCB Relay 2) will be energized(MM.F.B = ON). Motormaster Fan Circuit B will remain onuntil all compressors have been commanded off. If SCTB isabove the HPSP or if OAT is greater than 75°F, then condenserfan B (MBB Relay 5) will be energized (CD.F.B = ON) turningon OFC2. Condenser fan B will remain on until all compres-sors have been commanded off, or SCTB drops 40°F below theHPSP for greater than 2 minutes and OAT is less than 73°F.If either of the SCT or DPT sensors fails, then the control de-faults to head pressure control based on the OAT sensor. Thecontrol turns on the second fan stage when the OAT is above65°F and stages down when OAT drops below 50°F.If the OAT sensor fails, then the control defaults to head pressurecontrol based on the SCT sensors. The control turns on the secondfan stage when the highest active circuit SCT is above the HPSPand stages down when the highest active circuit SCT drops 40°Fbelow the HPSP for longer than 2 minutes.If the SCT, DPT, and OAT sensors have all failed, then the con-trol turns on the first and second fan stages when any compres-sor is commanded on.Compressor current sensor boards (CSB) are used on all unitsand are able to diagnose a compressor stuck on (welded contac-tor) condition. If the control commands a compressor off and theCSB detects current flowing to the compressor, then the first fanstage is turned on immediately. The second fan stage will turn onwhen OAT rises above 75°F or the highest active circuit SCT ris-es above the HPSP and remain on until the condition is repairedregardless of the OAT and SCT values.START-UPThe Motormaster V electronic control will be powered up aslong as unit voltage is present. When the system calls for cool-ing, the Motormaster relay (MMR) will be energized to initiatethe start-up sequence for the Motormaster V electronic control.The LED (light-emitting diode) will display the speed of themotor. The display range will be 8 to 60 Hz. TheMotormaster V electronic control will start the condenser fanwhen the compressor engages. The control will adjust the fanspeed to maintain head pressure setpoint. Above that pressure,the fan should operate at full speed.For size 48/50A 020-060 (RTPF) units, a single MotormasterV controller is used. For size 060 MCHX units, two Motormas-ter V devices are used, one for each circuit. Please refer toFig. Q for Motormaster V wiring details. The controller is con-figured by jumper wires and sensor input types. No field pro-gramming is required. If controller does not function properly,the information provided in the Troubleshooting section can beused to program and troubleshoot the drive.Drive ProgrammingTable M shows all program parameters for each of the operat-ing modes. Refer to Troubleshooting section before attemptingto change programming in the Motormaster V control.TO ENTER PASSWORD AND CHANGE PROGRAMVALUES:1. Press MODE.2. The display will read "00" and the upper right-hand decimalpoint will be blinking. This will activate the PASSWORDprompt (if the password has not been disabled).3. Use the UP and DOWN buttons to scroll to the passwordvalue (the factory default password is "111") and press theMODE button. Once the correct password value is entered,the display will read "P01", which indicates that the PRO-GRAM mode has been accessed at the beginning of the pa-rameter menu (P01 is the first parameter).NOTE: If the display flashes "Er", the password was incorrect,and the process to enter the password must be repeated.4. Press MODE to display present parameter setting. The upperright decimal point blinks. Use UP and DOWN buttons toscroll to the desired parameter number.5. Once the desired parameter number is found, press theMODE button to display the present parameter setting. Theupper right-hand decimal point will begin blinking, indicat-ing that the present parameter setting is being displayed. Usethe UP and DOWN buttons to change setting. Press MODEto store new setting.6. Press MODE to store the new setting and also exit the PRO-GRAM mode. To change another parameter, press theMODE button again to re-enter the PROGRAM mode (theparameter menu will be accessed at the parameter that waslast viewed or changed before exiting). If the MODE buttonis pressed within two minutes of exiting the PROGRAMmode, the password is not required to access the parameters.7. After two minutes, the password must be entered in order toaccess the parameters again.TO CHANGE PASSWORD — Enter the current passwordthen change P44 to the desired password.TO RESET FACTORY DEFAULTS — To recognize a factoryreset, the MMV controller must see a change in P48.1. Cycle power from Motormaster® V control.2. Enter PROGRAM mode by entering password.3. Scroll to P48 by using UP and DOWN buttons and thenpress MODE. One of the 12 mode numbers will appear.(Modes 1, 2 and 4 are used for these units.)CAUTIONIt is strongly recommended that the user NOT change anyprogramming without consulting Carrier service personnel.Unit damage may occur from improper.