37
Table 17 — PIC 5 Alarm Codes (cont)
ALARM
CODE
(ALARMRST)
ALARM TEXT
DESCRIPTION
RESET TYPE
ACTION TAKEN
BY CONTROL
POSSIBLE CAUSE
PROTECTIVE LIMITS (CONT)
Alm-253
ALM-253 Protective Limit
— High Discharge
Temperature
Manual
Unit shuts down.
Check for closed compressor discharge
isolation valve.
Check if chiller was operating in surge
conditions.
Check compressor discharge tempera-
ture sensor resistance or voltage drop.
Check for proper wiring to IOB connectors.
Check for proper condenser flow and
temperature.
Check for proper inlet guide vane and
optional diffuser actuator operation.
Check for COMP DISCHARGE TEMP >
220 F (104 C)
Check for fouled tubes, plugged water
strainers, or noncondensables in the
condenser.
Alm-254
ALM-254 Protective Limit
— Low Evaporator Refrig-
erant Temperature
Manual
Unit shuts down.
Check for proper refrigerant charge.
Check float valve operation.
Check for closed condenser liquid line
isolation valve.
If problem occurs at high load, check for
low condenser pressure which causes
inadequate refrigerant flow through con-
denser flasc orifices.
Check for proper chilled water flow and
temperature.
Confirm that condenser water enters bot-
tom row of condenser tubes first (reversed
condenser water flow may cause refriger-
ant to stack in the condenser).
Check evaporator pressure transducer
and evaporator refrigerant liquid tempera-
ture and leaving chilled water sensors.
Check for division plate gasket bypass.
Check for fouled tubes.
Check pressure transducer and tem-
perature sensor wiring to the IOB.
Alm-255
ALM-255 Protective Limit
— High Motor
Temperature
Manual
Unit shuts down.
Check compressor motor winding tem-
perature sensor accuracy and wiring to
IOB.
Check motor cooling line and spray noz-
zle for proper operation or restrictions.
Check motor cooling filter/drier and iso-
lation valves.
Look for refrigerant flow through motor
cooling line sight glass.
Check for excessive starts within a short
time span.
Alm-256
ALM-256 Protective Limit
— High Bearing
Temperature
Manual
Unit shuts down.
Check oil heater for proper operation;
confirm that oil heater is de-energized
when compressor is running.
Check for low oil level, partially closed
oil line isolation valves, or clogged oil
filter.
Check oil cooler refrigerant thermal
expansion valves; confirm that expan-
sion valve bulbs are secured to the oil
lines and insulated.
Check compressor bearing temperature
sensors accuracy and wiring to IOB.
This fault can result from excessive
operation at low load with low water flow
to the evaporator or condenser. Very
high discharge and volute temperatures
may increase the oil sump temperature.
Elevated sump temperature may result
from an excessively high oil level reach-
ing the bottom of the bull gear, causing it
to churn the oil.