Service manual

T -318
3-- 18
Table 3-6 Controller Alarm Indications (Sheet 1 of 3)
Code
No.
TITLE DESCRIPTION
AL11
Evaporator Motor 1
IP Trip
Alarm 11 is applicable to units with Single Evaporator Fan Capability (CnF32 set
to 1EFO) only. The alarm is triggered if the evaporator fan motor #1 internal
protector opens. If the alarm is active, probe check is deactivated.
AL12
Evaporator Motor 2
IP Trip
Alarm 12 is applicable to units with Single Evaporator Fan Capability (CnF32 set
to 1EFO) only. The alarm is triggered if the evaporator fan motor #2 internal
protector opens. If the alarm is active, probe check is deactivated.
AL20
Control Circuit Fuse
Open (24 vac)
Alarm 20 is triggered by control power fuse (F3A, F3B) opening and will cause
the software shutdown of all control units. This alarm will remain active until the
fuse is replaced.
AL21
Micro Circuit Fuse
Open (18 vac)
Alarm 21 is triggered by one of the fuses (F1/F2) being opened on 18 volts AC
power supply to the Controller. The suction modulation valve (SMV) will be
opened and current limiting is halted. Temperature control will be maintained by
cycling the compressor.
AL22
Evaporator Fan Mo-
tor Safety
Alarm 22 responds to the evaporator motor internal protectors. On units with
Normal Evaporator Fan Operation (CnF32 set to 2EFO) the alarm is triggered by
opening of either internal protector. It will disable all control units until the motor
protector resets. On units with Single Evaporator Fan Capability (CnF32 set to
1EFO), the alarm is triggered by opening of both internal protectors. It will disable
all control units until a motor protector resets.
AL24
Compressor Motor
Safety
Alarm 24 is triggered by the opening of the compressor motor internal protector .
This alarm will disable all control units except for the evaporator fans and will
remain active until the motor protector resets. This alarm triggers the failure
action code set by Function Code Cd29.
AL25
Condenser Fan Mo-
tor Safety
Alarm 25 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 condensing.
AL26
All Supply and Re-
turn temperature
Control Sensors
Failure
Alarm 26 is triggered if the Controller determines that all of the control sensors
are out-of-range. This can occur for box temperatures outside the range of -50 C
to +70 C (-58 F to +158 F). This alarm triggers the failure action code set by
Function Code Cd29.
AL27
Probe Circuit Cal-
ibration Failure
The Controller has a built-in Analog to Digital (A-D) converter, used to convert
analog readings (i.e. temperature sensors, current sensors, etc.) to digital read-
ings. The Controller continuously performs calibration tests on the A-D converter.
If the A-D converter fails to calibrate for 30 consecutive seconds, this alarm is
activated.This alarm will be inactivated as soon as the A-D converter calibrates.
AL50
Fresh Air Position
Sensor (VPS)
Alarm 50 is activated whenever the sensor is outside the valid range. There is a
five minute adjustment period where the user can change the vent position
without generating an alarm event. The sensor requires five minutes of no move-
ment to confirm stability. If the vent position changes at any point beyond the five
minute adjustment period, the sensor will generate an alarm event. The alarm is
triggered off when the unit power cycles and the sensor is within valid range.
AL51 Alarm List Failure
During start-up diagnostics, the EEPROM 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 activated. During control processing, any operation
involving alarm list activity that results in an error will cause Alarm 51 to be
activated. Alarm 51 is a “display only” alarm and is not written into the alarm list.
Pressing the ENTER key when “CLEAr” is displayed will result in an attempt to
clear the alarm list. If that action is successful (all alarms are inactive), Alarm 51
will be reset.
AL52 Alarm List Full
Alarm 52 is activated 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.
AL53 Battery Pack Failure
Alarm 53 is caused by the battery pack charge being too low to provide sufficient
power for battery-backed recording. Renew replaceable batteries. If this alarm
occurs on start up, allow a unit fitted with rechargeable batteries to operate for up
to 24 hours to charge rechargeable batteries sufficiently to deactivate the alarm