1-20
Revised 8-6-93
Alarm 24 --- Condenser Fan Motor
Alarm 24 is triggered by the opening of the
condenser motor internal protector and will disable all
control units except for the evaporator fans. This alarm
will remain active until the motor protector resets. This
alarm is deactivated if the unit is operating on water
cooled condensers.
Alarm 25 --- Compressor High Pressure
Alarm 25 is triggered when the compressor high
discharge pressure safety switch remains open for at least
one minute. This alarm will remain active until the
pressure switch resets, at which time the compressor will
restart.
Alarm 26 --- All Sensors Failure
Alarm 26 is triggered by a reading that all of the
control sensors are out-of-range. This can occur for box
temperatures outside the range of ---40
_
C (---40
_
F) to
+55
_
C (+131
_
F) or in the unlikely event that two (four
in DataCORDER unit) probes are bad. This alarm is
masked for 15 minutes to give the unit time to bring the
box within range. If the problem is that the unit is
out-of-range, the DTT is used to determine if the high or
low limit is being exceeded. If still out-of-range after 15
minutes, the probes are considered in error and the alarm
is triggered.
This alarm triggers the failure action code set by
Code Cd28.
Alarm 27 --- Probe Circuit Calibration Failure
Every second, the probe circuit current source is
checked for proper calibration. If after three consecutive
seconds, the current source cannot be brought into
calibration, Alarm 27 is triggered.
The controller continues to try to calibrate. The
alarm will remain active until successful calibration is
achieved.
Alarm 51 --- List Failures
During start-up diagnostics, the alarm list is
examined to determine validity of its contents. This is
done by testing the set point and the alarm list. If the
contents are invalid, Alarm 51 is set.
During control processing, any operation involving
alarm list activity that results in an error will cause Alarm
51 to be set.
Alarm 51 is a “display only” alarm and is not written
into the alarm list. Pressing the
alarm reset
key will result
in an attempt to clear the alarm list. If that action is
successful (all alarms are inactive), Alarm 51 will be reset.
Alarm 52 --- List Full
Alarm 52 is set whenever the alarm list is determined
to be full; at start-up or after recording an alarm in the
list. Alarm 52 is displayed, but is not recorded in the alarm
list.
This alarm can be reset by clearing the alarm list. This
can be done only if all alarms written in the list are
inactive.
Alarm 53 --- Main Voltage Sensor Failure
Alarm 53 is caused by a line voltage reading of less
than 30V. It is a display alarm with no associated failure
action. While Alarm 53 is active, no range testing will be
done of the line voltage and, for current test purposes, the
voltage will be assumed to be 460 vac. Alarm 53 will be
reset by any voltage reading greater than 30V.
Alarm 54 --- Primary Supply Air Sensor
Alarm 54 is set by an invalid primary supply sensor
reading outside the range of ---38 to +54
_
C. This alarm is
ignored during the first 15 minutes of operation. See
Alarm 26.
If Alarm 54 is set and the primary supply is the
control sensor, the secondary supply sensor will be used
for control.
Alarm 55 --- Secondary Supply Air Sensor
Alarm 55 is set by an invalid secondary supply sensor
reading outside the range of ---38 to +54
_
C. This alarm is
ignored during the first 15 minutes of operation. See
Alarm 26.
If Alarm 55 is set and the secondary supply is the
control sensor, the the primary return sensor will be used
for control.
Alarm 56 --- Primary Return Air Sensor
Alarm 56 is set by an invalid primary return sensor
reading outside the range of ---38 to +54
_
C. This alarm is
ignored during the first few minutes of operation. See
Alarm 26.
If Alarm 56 is set and the primary return is the
control sensor, the primary supply sensor will be used for
control.
Alarm 57 --- Secondary Return Air Sensor
(not applicable for some units)
Alarm 57 is set by an invalid secondary return sensor
reading outside the range of ---38 to +54
_
C. This alarm is
ignored during the first 15 minutes of operation. See
Alarm 26.
This sensor is only used for data logging and has no
backup.
Alarm 58 --- Ambient Temperature Sensor
Alarm 58 is triggered by an ambient temperature
outside the valid range from ---50
_
C (---58
_
F) to +70
_
C
(+158
_
F). This is a display alarm and has no associated
failure action.
Alarm 59 --- Heat Termination Thermostat (HTT)
Alarm 59 is triggered by the opening of the heat
termination thermostat and will result in the disabling of
the heater. This alarm will remain active until the
thermostat resets.
Alarm 60 --- Defrost Termination Thermostat (DTT)
Closed Failure
Alarm 60 is an indication of a probable failure
(closed) of the defrost termination thermostat (DTT). It
is triggered by the opening of the heat termination
thermostat (HTT) or the failure of the DTT to open
(within 1.0 to 1.5 hours depending on voltage) during
defrost.
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