123
cause a complete system shut down when communication fail-
ure occurs. Recovery is automatic. Reason for failure may be
due to incorrect wiring, power loss to the EXB board, or dam-
age to the RS-485 drivers on the LEN bus.
A175 (Supply Fan VFD Communication Failure)
— The
supply fan is disabled until communication with the supply fan
VFD is re-established. Recovery is automatic. Reason for fail-
ure may be due to incorrect wiring, power loss to the VFD, or
damage to the RS-485 drivers on the LEN bus.
T176 (Exhaust Fan VFD Communication Failure)
— The
exhaust fan is disabled until communication with the exhaust
fan VFD is re-established. Recovery is automatic. Reason for
failure may be due to incorrect wiring, power loss to the VFD,
or damage to the RS-485 drivers on the LEN bus.
T177 (4-20 mA Demand Limit Failure)
— If this transducer
fails, and the unit is configured to perform demand limiting
with this transducer, no capacity limiting will be performed and
an alert will be generated. Recovery is automatic. Reason for
error is either a faulty sensor, wiring error, or damaged input on
the CEM control board.
T178 (4-20 mA Static Pressure Reset Fail)
— If this trans-
ducer fails, and the unit is configured to perform static pressure
reset with this transducer, no static pressure reset will be per-
formed and an alert will be generated. Recovery is automatic.
Reason for error is either a faulty sensor, wiring error, or dam-
aged input on the CEM control board.
A179 (Cir A EXV Control Board Comm Failure)
A180 (Cir B EXV Control Board Comm Failure) — Alarm
codes 179 and 180 are for circuits A and B respectively. The
EXV PCBs are integral to the proper functionality of each re-
frigeration circuit. The corresponding circuit is disabled until
communications with the EXV is re-established. Recovery is
automatic. Reason for failure may be due to incorrect wiring,
power loss to the EXB board, or damage to the RS-485 drivers
on the LEN bus.
A200 (Linkage Timeout Error — Comm Failure)
— If link-
age is established via the CCN with ComfortID™ terminals, a
5-minute timeout on loss of communication will be monitored.
If 5 minutes expires since the last communication from a VAV
Linkage Master, the unit will remove the link and flag the alert.
When the rooftop loses its link, the temperature and set points
are derived locally. Recovery is automatic on re-establishment
of communications. Reason for failure may be wiring error, too
much bus activity, or damaged RS-485 drivers.
T210 (Building Pressure Transducer Failure)
— If the build-
ing pressure transducer (Pressures
AIR.P
BP) fails, build-
ing pressure control fails also. Recovery is automatic. Reason
for error is either a faulty sensor, wiring error, or damaged in-
put on the RXB control board.
T211 (Static Pressure Transducer Failure)
— If the static
pressure transducer (Pressures
AIR.P
SP) fails, static pres-
sure control fails also. Recovery is automatic. Reason for error
is either a faulty sensor, wiring error, or damaged input on the
RXB control board.
T220 (Indoor Air Quality Sensor Failure)
— If the indoor air
quality sensor (Inputs
AIR.Q
IAQ) fails, demand control
ventilation is not possible. The control defaults to the max vent
position. Recovery is automatic. Reason for error is either a
faulty sensor, wiring error, or damaged input on the MBB con-
trol board.
T221 (Outdoor Air Quality Sensor Failure)
— If the out-
door air quality sensor (Inputs
AIR.Q
OAQ) fails, OAQ
defaults to 400 ppm and demand control ventilation will
continue. Recovery is automatic. Reason for error is either a
faulty sensor, wiring error, or damaged input on the CEM
control board.
T229 (Economizer Min Pos Override Input Failure)
— If
the economizer minimum position override input fails, the
economizer will operate as if it were not configured for
override. Recovery is automatic. Reason for error is either a
faulty sensor, wiring error, or damaged input on the MBB con-
trol board. This error only occurs when the unit is configured
for minimum position override and a 4 to 20 mA signal is not
present.
T245 (Outside Air Cfm Sensor Failure)
— If the outside air
cfm sensor (Inputs
CFM
O.CFM) fails, the economizer
will default to discrete positioning of the economizer (Con-
figuration
IAQ
DCV.C
IAQ.M, Configuration
ECON
EC.MN). Recovery is automatic. Reason for error
is either a faulty sensor, wiring error, or damaged input on
the CEM control board.
T246 (Supply Air Cfm Sensor Failure)
— If the supply air
cfm sensor (Inputs
CFM
S.CFM) fails, fan tracking is not
possible and the system will shut down. Recovery is automatic.
Reason for error is either a faulty sensor, wiring error, or dam-
aged input on the EXB control board.
T247 (Return Air Cfm Sensor Failure)
— If the return air
cfm sensor (Inputs
CFM
R.CFM) fails, fan tracking is not
possible and the system will shut down. Recovery is automatic.
Reason for error is either a faulty sensor, wiring error, or dam-
aged input on the EXB control board.
T248 (Exhaust Air Cfm Sensor Failure)
— If the exhaust air
cfm sensor (Inputs
CFM
E.CFM) fails, exhaust air cfm
will not be properly reported. Recovery is automatic. Reason
for error is either a faulty sensor, wiring error, or damaged in-
put on the EXB control board.
T300 (Space Temperature Below Limit)
— If the space tem-
perature is below the configurable SPT Low Alert Limits (occu-
pied [Configuration
IAQ
ALLM
SP.L.O] for 5 minutes or
unoccupied [Configuration
IAQ
ALLM
SP.L.U] for 10
minutes), then an alert will be broadcast. The alert will automati-
cally reset.
T301 (Space Temperature Above Limit)
— If the space tem-
perature is above the configurable SPT High Alert Limits
(occupied [Configuration
IAQ
ALLM
SP.H.O] for 5
minutes or unoccupied [Configuration
IAQ
ALLM
SP.H.U] for 10 minutes), then an alert will be broadcast. The
alert will automatically reset.
T302 (Supply Temperature Below Limit)
— If the supply-air
temperature measured by the supply temperature sensor is below
the configurable SAT LO Alert Limit/Occ (Configura-
tion
IAQ
ALLM
SA.L.O) for 5 minutes or the Low Sup-
ply air temperature alert limit unoccupied mode (Configura-
tion
IAQ
ALLM
SA.L.U) for 10 minutes, then an alert
will be broadcast.
T303 (Supply Temperature Above Limit)
— If the supply
temperature is above the configurable SAT HI Alert Limit Occ
(Configuration
IAQ
ALLM
SAH.O) for 5 minutes or
the SAT HI Alert Limit/Unocc (Configuration
IAQ
ALLM
SA.H.U) for 10 minutes, then an alert will be broad-
cast. The alert will automatically reset.
T304 (Return Air Temperature Below Limit)
— If the re-
turn air temperature measured by the RAT sensor is below the
configurable RAT LO Alert Limit/Occ (Configura-
tion
IAQ
ALLM
RA.L.O) for 5 minutes or RAT HI Alert
Limit/Occ (Configuration
IAQ
ALLM
RA.L.U) for 10
minutes, then an alert will be broadcast.
T305 (Return Air Temperature Above Limit)
— If the return
air temperature is below the RAT HI Alert Limit/Occ (Configu-
ration
IAQ
ALLM
RA.H.O) for 5 minutes or RAT HI
Alert Limit/Occ (Configuration
IAQ
ALLM
RA.H.U)
for 10 minutes, then an alert will be broadcast. The alert will au-
tomatically reset.
T308 (Return Air Relative Humidity Below Limit)
— If the
unit is configured to use a return air relative humidity sensor
through the Return Air RH Sensor (Configuration
UNIT
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