Operating instructions

TM 11574A-OI
2-62
h. Controller Alarms.
Alarm display is an independent controller software function. If an operating parameter is outside
of expected range or a component does not return the correct signals back to the controller, an
alarm is generated. A listing of the alarms is provided in Table 2-6. The alarm philosophy
balances the protection of the refrigeration unit and that of the refrigerated cargo. The action
taken when an error is detected always considers the survival of the cargo. Rechecks are made
to confirm that an error actually exists. Some alarms requiring compressor shutdown have time
delays before and after to try to keep the compressor on line. An example is alarm code “LO,”
(low main voltage), when a voltage drop of over 25% occurs, an indication is given on the display,
but the unit will continue to run. An alarm is indicated by flashing an alarm code on the display
panel, and for some alarms, by the alarm light illuminating.
When an Alarm Occurs:
1. The red alarm light will illuminate for “20 series” alarms.
2. If a detectable problem is found to exist, its alarm code will be alternately displayed with
the set point on the left display.
3. The user should scroll through the alarm list to determine what alarms exist or have
existed. Alarms must be diagnosed and corrected before the Alarm List can be cleared.
To Display Alarm Codes:
1. While in the Default Display mode, press the ALARM LIST key. This accesses the Alarm
List Display Mode, which displays any alarms archived in the Alarm Queue.
2. The alarm queue stores up to 16 alarms in the sequence in which they occurred. The
user may scroll through the list by depressing an ARROW key.
3. The left display will show “AL##,” where ## is the alarm number sequentially in the
queue.
4. The right display will show the actual alarm code. “AA##” will display for an active alarm,
where “##” is the alarm code. Or “IA##” will display for an inactive alarm (refer to Table
2-6).
5. “END” is displayed to indicate the end of the alarm list if any alarms are active.
6. “CLEAr” is displayed if all alarms are inactive. The alarm queue may than be cleared by
pressing the ENTER key. The alarm list will clear and “ -- -- -- -- -- ” will be displayed.
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.