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APPENDIX 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 circuit
SCT is above the HPSP or if OAT is greater than 75°F then
condenser fan B (MBB Relay 5) will be energized (CD.F.B =
ON). Condenser fan B will remain on until all compressors
have been commanded off, or the highest active circuit SCT
drops 40°F below the HPSP for greater than 2 minutes and
OAT is less than 73°F.
NOTE: For size 60 units with RTPF condenser heat exchangers
not configured for Motormaster control, the control stages down
differently than the other units. For these units, the control will
first turn off condenser fan relay A. After 2 minutes, the control
will turn off relay B and turn back on relay A.
For 48/50A060 size units with MCHX condensers, there are
four 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 until
all compressors have been commanded off. If SCTA is above the
HPSP or if OAT is greater than 75°F, then condenser fan A (MBB
Relay 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 than
2 minutes and OAT is less than 73°F.
When a circuit B compressor has been commanded on, then
Motormaster Fan Circuit B (SCB Relay 2) will be energized
(MM.F.B = ON). Motormaster Fan Circuit B will remain on
until all compressors have been commanded off. If SCTB is
above the HPSP or if OAT is greater than 75°F, then condenser
fan B (MBB Relay 5) will be energized (CD.F.B = ON) turning
on OFC2. Condenser fan B will remain on until all compres-
sors have been commanded off, or SCTB drops 40°F below the
HPSP 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. The
control turns on the second fan stage when the OAT is above
65°F and stages down when OAT drops below 50°F.
If the OAT sensor fails, then the control defaults to head pressure
control based on the SCT sensors. The control turns on the second
fan stage when the highest active circuit SCT is above the HPSP
and stages down when the highest active circuit SCT drops 40°F
below 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 units
and are able to diagnose a compressor stuck on (welded contac-
tor) condition. If the control commands a compressor off and the
CSB detects current flowing to the compressor, then the first fan
stage is turned on immediately. The second fan stage will turn on
when OAT rises above 75°F or the highest active circuit SCT ris-
es above the HPSP and remain on until the condition is repaired
regardless of the OAT and SCT values.
START-UP
The Motormaster V electronic control will be powered up as
long as unit voltage is present. When the system calls for cool-
ing, the Motormaster relay (MMR) will be energized to initiate
the start-up sequence for the Motormaster V electronic control.
The LED (light-emitting diode) will display the speed of the
motor. The display range will be 8 to 60 Hz. The
Motormaster V electronic control will start the condenser fan
when the compressor engages. The control will adjust the fan
speed 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 Motormaster
V controller is used. For size 060 MCHX units, two Motormas-
ter V devices are used, one for each circuit. Please refer to
Fig. 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 be
used to program and troubleshoot the drive.
Drive Programming
Table M shows all program parameters for each of the operat-
ing modes. Refer to Troubleshooting section before attempting
to change programming in the Motormaster V control.
TO ENTER PASSWORD AND CHANGE PROGRAM
VA L UE S:
1. Press MODE.
2. The display will read "00" and the upper right-hand decimal
point will be blinking. This will activate the PASSWORD
prompt (if the password has not been disabled).
3. Use the UP and DOWN buttons to scroll to the password
value (the factory default password is "111") and press the
MODE 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 upper
right decimal point blinks. Use UP and DOWN buttons to
scroll to the desired parameter number.
5. Once the desired parameter number is found, press the
MODE button to display the present parameter setting. The
upper right-hand decimal point will begin blinking, indicat-
ing that the present parameter setting is being displayed. Use
the UP and DOWN buttons to change setting. Press MODE
to store new setting.
6. Press MODE to store the new setting and also exit the PRO-
GRAM mode. To change another parameter, press the
MODE button again to re-enter the PROGRAM mode (the
parameter menu will be accessed at the parameter that was
last viewed or changed before exiting). If the MODE button
is pressed within two minutes of exiting the PROGRAM
mode, the password is not required to access the parameters.
7. After two minutes, the password must be entered in order to
access the parameters again.
TO CHANGE PASSWORD — Enter the current password
then change P44 to the desired password.
TO RESET FACTORY DEFAULTS — To recognize a factory
reset, 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 then
press MODE. One of the 12 mode numbers will appear.
(Modes 1, 2 and 4 are used for these units.)
CAUTION
It is strongly recommended that the user NOT change any
programming without consulting Carrier service personnel.
Unit damage may occur from improper.
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