Alarms; Phase - Voltage Detection; Service Relays - Lennox Core Unit Controller Setup Manual

13. Alarms

13.1. Phase - Voltage Detection

The CORE Unit Controller has the ability to detect that the rooftop unit power source has the correct frequency, phasing
and voltage levels. When this feature is enabled, the detection of frequency and phasing is determined at power-on and the
voltage level is continuously monitored. If any of these is out of range, then an alarm is logged and the rooftop unit operation
is locked out.
a. Alarms Detected at Power-On Start up:
• 121 - LINE FREQ DOES NOT MATCH UNIT CONFIG
• 126 - LINE PHASING DOES NOT MATCH UNIT CONFIG
b. Alarms - Continuously Monitoring
• 122 - 24VAC PRIMARY VOLTAGE LOW
• 123 - 24VAC PRIMARY VOLTAGE HIGH
• 134 - 24VAC SECONDARY VOLTAGE LOW
• 125 - 24VAC SECONDARY VOLTAGE HIGH
Alarms 122 through 125 are auto-resetting. The rooftop operation will be restored five (5) minutes after the proper voltage
levels are restored. Alarms 121 and 126 requires removing the power and correcting the issue before restoring the rooftop
operation.
The frequency (60 or 50 Hz) and the phasing (single or three-phase) of the power source is determined by the model
number stored in the CORE Unit Controller. This model number and enabling/disabling the Phase-Voltage Detection feature
can be modified through the CORE Unit Controller user interface. See the Installation and Setup Guide for instructions on
how to configure the CONFIGURATION ID 2, Position 5. Options are:
• N = NOT INSTALLED
• 1 = ENABLED INTERNAL (LENNOX)
• 2 = EXTERNAL (A42) PHASE DETECTION ON DI-2
• 3 = EXTERNAL (A42) PHASE DETECTION ON DI-3
When an event occurs, the CORE Unit Controller will display a code which corresponds to control function. Error codes are
stored and can be recalled later.
NOTE: Any references in the user interface referencing Advanced Airflow actually indicates SmartAirflow

13.2. Service Relays

Selected alarms (marked with * in the following table result in the closure of the service relay contacts (DO1). The contacts
remain closed until the CORE Unit Controller resets, or alarm condition is cleared and alarm status is read via explicit S-BUS
command. Other modes of operation may be selected and are described in the CORE Unit Controller Application Guide
(Advanced Features).
NOTE: Any references in the user interface referencing Advance Airflow actually indicates SmartAirflow
13.3. CORE Unit Controller Alarm and Event Codes
SELECTED ALARMS (MARKED WITH * IN TAbLE RESULT IN THE CLOSURE OF THE SERVICE RELAY CONTACTS (DO1).
ALARM
DISPLAY MESSAGE
CODE
ERRATIC POWER
1
(single phase units)
2 PARAMETER ACCESS ERROR
3 RESERVED
4* SMOKE
Table 11. CORE Control System Alarm and Event Codes
EVENT ACTION
Power loss for two cycles. This may indicate that the unit power is dirty or is of low quality.
Check power connections.
The CORE Unit Controller will set an alarm "Erratic Power" whenever service is turned off
due to detection of power loss. User will be able to clear "Erratic Power" alarm via user
interface. The CORE Unit Controller will clear "Power Erratic" after the Compressor Min
OFF Delay has expired. If compressor demand is still present the CORE Unit Controller
will restart compressor(s) after the Compressor Min OFF Delay has expired.
Parameter access error. This may indicate a problem with the Parameter memory chip and
parameters may not be changeable.
A173 input is sensed as closed. Will automatically clears once input is detected open. For
smoke mode, check for source of smoke. While Smoke Alarm is active, the CORE Unit
Controller will not service any cooling, heating or ventilation demands.
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