Lennox Core Unit Controller Setup Manual page 44

SELECTED ALARMS (MARKED WITH * IN TAbLE RESULT IN THE CLOSURE OF THE SERVICE RELAY CONTACTS (DO1).
ALARM
DISPLAY MESSAGE
CODE
124* 24VAC SECONDARY VOLTAGE LOW
125* 24VAC SECONDARY VOLTAGE HIGH
126* LINE PHASING MISMATCH
127 ALARM BUFFER OVERLFOW
128 24VAC SECONDARY POWER LOSS
129* VFD SHUTDOWN
130 VFD BYPASS ENGAGED
131 RESERVED
132 VFD BYPASS UNCONFIG
133 RESERVED
134 LOW SUPPLY AIRFLOW
135* NO SUPPLY AIRFLOW
136* OA DAMPER MECH FAULT
137 LOW OUTDOOR AIRFLOW
138 RESERVED
139 HIGH OUTDOOR AIRFLOW
140 CFM TARGET TOO LOW
141 CFM TARGET TOO HIGH
142 RESERVED
143* OA DAMPER ERROR
144 FIRMWARE UPDATE COMPLETED
145 RESERVED
146 SERVICE EVENT
147* DAMPER FDBK LOSS
148* EP CONFIG ERROR
149* OA DIFF PRESS SENSOR ERROR
150* NOT ECONOMIZING WHEN OAS
151* ECONOMIZING WHEN OANS
152 - 162 RESERVED
163 LIQUID PRESS OPEN
164 STRIKE3 LIQUID PRESS OPEN
165 ECN UNCONFIGURED
Table 11. CORE Control System Alarm and Event Codes
EVENT ACTION
• Low output voltage on T1 transformer. alarm set when 24VAC voltage low if
calculated RMS voltage is below low voltage alarm threshold for more than two
seconds. System will stop unit operations (cooling, heating and ventilation). Low
voltage threshold is 18VAC.
• The CORE Unit Controller will clear alarm 24VAC Voltage Low if calculated RMS
voltage is above Low Voltage Alarm Threshold + 1 VAC for more than two seconds.
After the low 24VAC alarm has been cleared, the CORE Unit Controller will ignore all
service demands until the Error Time Off Delay has expired.
• High output voltage on T1 transformer. alarm set when 24VAC voltage high if
calculated RMS voltage is below low voltage alarm threshold for more than two
seconds. System will stop unit operations (cooling, heating and ventilation). Low
voltage threshold is 30VAC.
• The CORE Unit Controller will clear alarm 24VAC Voltage HIGH if calculated RMS
voltage is above high voltage alarm Threshold + 1 VAC for more than two seconds.
After the high 24VAC alarm has been cleared the CORE Unit Controller will ignore all
service demands until the Error Time Off Delay has expired.
During power up or reset of unit, Mismatch on single or 3 phase power, or reverse rotation
on 3 phase detected. This alarm is enabled by the Phase Voltage Detection feature.
Alarm buffer overflow.
Check transformer and wire connections.
VFD fault detected. Check belt and for blower overload. Fix source of fault and reset
CORE Unit Controller.
VFD bypass mode. Mode is engaged. Blower may or may not be disengage.
VFD bypass mode has not been selected. Unit operates as if bypass is not installed.
Advanced Airflow enabled RTU indicates airflow target cannot be achieved. Check cause
of airflow reduction such as dirty filter, changes in duct work, etc
Blower RPM is too low as indicates by blower status. This means that the blower is not
working. Repair blower and reset CORE Unit Controller.
Outdoor air damper stuck or actuator problem.
Outdoor airflow is too low so the building is not getting the designed outdoor airflow based
on IAQ.
Ventilation CFM is too high therefore the RTU is using excessive energy.
Verify the MSAV blower settings and set the CM targets below set CFM. The alarm value
will be displayed on the CORE Unit Controller screen.
Outdoor air differential pressure sensor value not in valid range. Might be tubing problem
or high return duct resistance.
System updated with new firmware.
Service event logged.
During free cooling damper is not modulating.
Economizer should be installed and blower should be ECM type.
Check outdoor air damper differential pressure sensor and wiring.
May be due to the damper motor being unplugged or disconnected.
This may be due to damper motor being blocked or stuck open and therefore not closing.
Configuration ID 1, position 2 is set to U. Select applicable option using setup/install
wizard.
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