162
TROUBLESHOOTING
Table 78 is an abbreviated list of symptoms, probable
causes, and potential remedies.
Alarms and Alerts — These are warnings of abnormal
or fault conditions, and may cause either one circuit or the
whole unit to shut down. They are assigned code numbers as
listed in Table 79. Active pre-alerts/alerts/alarms are shown in
Currently Active Alarms, Alarms
CRNT. Up to 20 current
alarms will be displayed. Pressing and
buttons simultaneously will expand the alarm code description
only. Time and date stamps are available in Alarm History.
If the unit is in alarm and unable to operate, Control Mode
will show Run Status
VIEW
STAT=4 (Off Emrgcy). Au-
tomatic alarms will reset without operator intervention if the
condition corrects itself. Manual alarms will require operator
intervention to reset the alarm.
RESETTING ALARMS — Before resetting any alarm, first
determine the cause of the alarm and correct it. After determin-
ing and correcting the cause of the alarm, toggle
Alarms
RCRN (Reset All Current Alarms) from NO to
YES. The control may prompt the user for a password, by dis-
playing PASS and WORD. See Configuration and Service
Password on page 22 for information on the password. If the
condition has been resolved, the alerts/alarms will be cleared
from the active alert/alarm set.
ALARM HISTORY — The scrolling marquee and Naviga-
tor
™
display have the ability to display the latest alarms and
alerts up to 20 events. This is a first-in, first-out alarm buffer.
As a Pre-alert, Alert, or Alarm is generated, it is written to the
Alarm History. To access Alarm History, enter Alarms
HIST.
Use the arrow keys to move through the history. The latest pre-
alerts, alerts and alarms will appear first on the list. Pressing
and simultaneously will provide a time
and date stamp and expand the pre-alert/alert/alarm code.
Table 78 — Troubleshooting
SYMPTOM POSSIBLE CAUSES POSSIBLE REMEDIES
Unit does not run
Check for power to unit Check overcurrent protection device.
Check non-fused disconnect (if equipped).
Restore power to unit.
Check for 24 volts at the control boards.
Wrong/incorrect unit configuration Check unit configuration.
If unit is controlled by a Local Schedule, check to
be sure that the Day of the Week is properly set.
Enable-Off-Remote Switch is not in a position to
allow the unit to operate.
Fan Status Switch is open.
Active alarm Check alarm status. See Alarms and Alerts begin-
ning on page 162 and follow troubleshooting
instructions.
Active operating mode Check for Operating Modes. See the Operating
Modes section beginning on page 135 and follow
troubleshooting instructions.
No cooling load Cooling Load is satisfied.
Unit runs when it is not called for Incorrect unit configuration If unit is controlled by a Local Schedule, check to
be sure that the Day of the Week is properly set.
Unit operates too long or continuously
Low refrigerant charge Check for leak and add refrigerant.
Compressor or control contacts welded Replace contactor or relay.
Non-condensables in refrigerant circuit Remove refrigerant and recharge.
Circuit does not run
Active alarm Check alarm status. See Alarms and Alerts begin-
ning on page 162 and follow troubleshooting
instructions.
Active operating mode Check for Operating Modes. See the Operating
Modes section beginning on page 135 and follow
troubleshooting instructions.
Circuit does not load
Active alarm Check alarm status. See Alarms and Alerts begin-
ning on page 162 and follow troubleshooting
instructions.
Active operating mode Check for Operating Modes. See the Operating
Modes section beginning on page 135 and follow
troubleshooting instructions.
Low Saturated Suction Temperature See Alarms, Pre-Alerts, and Alerts A120, A121,
P120,121, T120,121, page 168.
Faulty compressor discharge check-valve Replace compressor.
Compressor does not run
Active alarm Check alarm status. See Alarms and Alerts begin-
ning on page 162 and follow troubleshooting
instructions.
Active operating mode Check for Operating Modes. See the Operating
Modes section beginning on page 135 and follow
troubleshooting instructions.
Inoperative compressor contactor Check control wiring.
Check contactor operation, replace if necessary.
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