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APPENDIX F — OPTIONAL FACTORY-INSTALLED LOW AMBIENT MOTORMASTER
®
V CONTROL (cont)
TROUBLESHOOTING
Troubleshooting the Motormaster V control requires a combina-
tion of observing system operation and VFD display information.
If the liquid line pressure is above the setpoint and the VFD is
running at full speed, this is a normal condition. The fan CAN-
NOT go any faster to maintain setpoint.
If the VFD is not slowing down even though liquid line pres-
sure is below setpoint, the VFD could be set for manual control
or the control may be receiving faulty pressure transducer out-
put. Corrective action would include:
• Check that VDC signal between TB5 and TB2 is between
0.5 V and 4.5 V.
• Restore VFD to automatic control.
• Change parameter P05 back to correct value shown in
Table M.
The Motormaster V control also provides real time monitoring
of key inputs and outputs. The collective group is displayed
through parameters P50 to P56 and all values are read only.
These values can be accessed without entering a password.
Press MODE twice and P50 will appear. Press MODE again to
display value.
To scroll to P51-P56 from P50, use UP and DOWN buttons
then press MODE to display the value.
• P50: FAULT HISTORY - Last 8 faults
• P51: SOFTWARE version
• P52: DC BUS VOLTAGE - in percent of nominal. Usual-
ly rated input voltage x 1.4
• P53: MOTOR VOLTAGE - in percent of rated output
voltage
• P54: LOAD - in percent of drives rated output current
• P55: VDC INPUT - in percent of maximum input: 100%
will indicate full scale which is 5 v
• P56: 4-20 mA INPUT - in percent of maximum input.
20% = 4 mA, 100% = 20 mA
NOTE: The Motormaster V transducer is attached to circuit A. If
circuit A compressor power is interrupted (overload, high pressure
cutout, etc.) the outdoor fans will operate at a reduced speed re-
sulting from erroneous low pressure readings. This process may
cause a high pressure safety cutout on circuit B compressor. If
only circuit B is capable of operating for a temporary period of
time because of a circuit A problem, the transducer will have to be
moved to the circuit B service port until circuit A can be repaired.
Once the problem is repaired, move the transducer back to circuit
A for proper unit operation.
Fault Lockout
If a fault lockout (LC) has occurred, view the fault history in P50
to find the last fault. Once P50 is displayed, use the arrow but-
tons to scroll through the last 8 faults. Any current faults or fault
codes from the fault history can be analyzed using Table N.
TO DISABLE AUTOMATIC CONTROL MODE AND EN-
TER MANUAL SPEED CONTROL:
1. Change P05 to '01- keypad.'
2. Push UP and DOWN arrow button to set manual speed.
3. Set P05 to proper value to restore automatic control accord-
ing to Table M.
TO PROVIDE MANUAL START/STOP CONTROL — With
power removed from VFD, remove start command jumper and
install a switch between the appropriate start terminals as re-
quired in Table L.
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