Installation, Operation and Maintenance 10 - 7
Low Differential
Rfgt Pressure
MMR Friendly A low differential temperature/pressure condition was detected that
lasted for more than 240 continuous seconds. The trip point is 23.8
psid.
Check Condsr
Water Temp Too
Low and EXV
Low Differential
Refgt Press
Switch
MAR N/A If the 7.7 psid system differential pressure switch is not open on the
attempt to start, the MAR diagnostic will keep the unit latched out
until the switch is opened.
Check Low
Differential
Pressure Switch &
its Valving, EXV
Low Discharge
Superheat
MMR Friendly a.While Running Normally, the Discharge Superheat was less than
12
°
F +/- 1
°
F for more than 6500
°
F seconds. The must hold value is
13
°
F while the must integrate value is 11
°
F.
b. At start-up the UCP2 shall ignore the Discharge Superheat for a
minimum of 5 minutes and a maximum of 5.5 minutes.
See
Troubleshooting
Service Bulletin
Low Evaporator
Liquid Level
MMR Friendly The liquid level sensor is seen to be at or near its low end of range
for 80 continuous minutes while the compressor is running
Check EXV Sensor,
Stpr Module & Rfgt
Charge
Low Evap Rfgt
Temp.
MMR Immediate a. The Saturated Evap Rfgt Temp dropped below the Low Rfgt
Temp. Cutout Setpoint when the circuit was running for 60
°
F
seconds. The diagnostic is ignored during the first minute of
operation after a start. Special Note: During time-out of trip integral,
the unload solenoid is energized continuously and the load solenoid
de-energized continuously. Normal load/unload operation is
resumed if the trip integral is reset by return to temperatures above
the cutoff setpoint.
Check Oil Sump
Vent Line Valve, Oil
Return System.
Check for Oil
Overcharge
Low Oil Flow MMR MMR The oil flow pressure switch detects no flow (high differential
pressure/high logic state) for 5 continuous seconds while running.
Check Oil System
(Master Oil Line
Solenoid Valve &
Oil Filter, Hand
Valves and Diff.
Pressure Switch)
Low Pressure
Cutout
MMR Immediate The Low Pressure Cutout opened for more than 0.5-2 Seconds.
C.O. on fall @ 0 psig (+/- 3 psi), reset @ 20 psig (+/-5psi). The LPC
is set primarily to detect significant charge loss and thus ignore
times at start-up are not required (The sat evap temp sensor is used
for low temp / low pressure detection but it cannot function if
saturated conditions are not present such as in the event of charge
loss)
See
Troubleshooting
Service Bulletin
Max Acceleration
Setpts
Error
IFW N/A a. The redundant Maximum Acceleration settings did not agree for
30 continuous seconds. (Continue to use the previous value for the
30 second time-out.) When this diagnostic occurs, the affected
Starter Module shall use 6 seconds as a default until either the
UCP2 is reset or, if the redundant settings agree again, the starter
module can go back to using the actual setting.
Review Max
Acceleration Set Up
Memory Error
Type IV
IFW N/A A page time-out error was detected while trying to write data into
EEPROM. There will likely be a recall of Engineering ROM defaults
on the next reset or power transition. Replace the Chiller Module as
soon as a replacement is available.
Call Service to
Check all Settings
Memory Error
Type II: Shadow
RAM
IFW N/A a. A Shadow RAM memory error was detected. The UCP2 is
operating on all last valid values (pulled from NOVRAM) for all setup
parameters. No setup parameter changes were pending to be
loaded into NOVRAM, a complete recovery of all setup parameters
was made and there is no need to check unit setup parameters.
Compressor starts and hours were lost for not more than the last 24
hours. This is expected to be an isolated event and repair or
replacement is not required. If this diagnostic occurs repeatedly,
then replace the Chiller module.
No Settings Were
Lost
Diagnostic
Description
Diagnostic
Type
Shutdown
Action
Cause Help Message
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