Operating instructions

TM 11574A-OI
2-31
Table 2-7 Controller Alarm Indications
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
Motor Safety
A
larm 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
Motor 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.
AL26
All Supply and
Return 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. Check the connector at the back of the controller, if it is loose or unplugged,
reconnect it. Then run a pre trip test (P5) to clear AL26.
AL27
Probe Circuit
Calibration 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 readings.
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 movement 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.