Carrier WeatherExpert 48N2 Controls, Start-Up, Operation, Service, And Troubleshooting page 130

alert. When the rooftop loses its link, the temperature and set
points are derived locally. Recovery is automatic on re-establish-
ment of communications. Reason for failure may be wiring er-
ror, too much bus activity, or damaged RS-485 drivers.
T210 (Building Pressure Transducer Failure)
If the building pressure transducer (Pressures  AIR.P  BP)
fails, building pressure control fails also. Recovery is automat-
ic. Reason for error is either a faulty sensor, wiring error, or
damaged input on the RXB control board.
T211 (Static Pressure Transducer Failure)
If the static pressure transducer (Pressures  AIR.P  SP) fails,
static pressure control fails also. Recovery is automatic. Rea-
son 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 controlled ventilation is not possible. The control de-
faults to the max vent position. Recovery is automatic. Reason
for error is either a faulty sensor, wiring error, or damaged in-
put on the MBB control board.
T221 (Outdoor Air Quality Sensor Failure)
If the outdoor air quality sensor (Inputs  AIR.Q  OAQ) fails,
OAQ defaults to 400 ppm and demand controlled 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 control board. This
error only occurs when the unit is configured for minimum posi-
tion 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 econ-
omizer (Configuration  IAQ  DCV.C  IAQ.M, Configura-
tion  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. Re-
covery is automatic. Reason for error is either a faulty sensor,
wiring error, or damaged 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. Recov-
ery is automatic. Reason for error is either a faulty sensor, wir-
ing error, or damaged 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 au-
tomatic. Reason for error is either a faulty sensor, wiring error,
or damaged input on the EXB control board.
T300 (Space Temperature Below Limit)
If the space temperature is below the configurable SPT Low Alert
Limits (occupied [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 au-
tomatically reset.
T301 (Space Temperature Above Limit)
If the space temperature 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 tempera-
ture sensor is below the configurable SAT LO Alert Limit/Occ
(Configuration  IAQ  ALLM  SA.L.O) for 5 minutes or the
Low Supply air temperature alert limit unoccupied mode (Con-
figuration  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 (Configura-
tion  IAQ  ALLM  SA.H.U) for 10 minutes, then an alert
will be broadcast. The alert will automatically reset.
T304 (Return Temperature Below Limit)
If the return air temperature measured by the RAT sensor is be-
low 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)
10 minutes, then an alert will be broadcast.
T305 (Return Temperature Above Limit)
If the return air temperature is below the RAT HI Alert Limit/Occ
(Configuration  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 auto-
matically 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 (Configura-
tion  UNIT  SENS  RRH.S) setting, and the measured lev-
el is below the configurable RH Low Alert Limit (Configura-
tion  IAQ  ALLM  R.RH.L) for 5 minutes, then the alert
will occur. The unit will continue to run and the alert will auto-
matically reset.
T309 (Return Air Relative Humidity Above Limit)
If the unit is configured to use a return air relative humidity sensor
through the Return Air RH Sensor (Configuration  UNIT 
SENS  RRH.S) setting, and the measured level is above the con-
figurable RH High
IAQ  ALLM  R.RH.H) for 5 minutes, then the alert will occur.
Unit will continue to run and the alert will automatically reset.
T310 (Supply Duct Static Pressure Below Limit)
If the unit is a VAV unit with a supply duct pressure sensor and
the measured supply
sures  AIR.P  SP) is below the configurable SP Low Alert
Limit (Configuration  IAQ  ALLM  SP.L) for 5 minutes,
then the alert will occur. The unit will continue to run and the
alert will automatically reset.
T311 (Supply Duct Static Pressure Above Limit)
If the unit is a VAV unit with a supply duct pressure sensor and
measured supply duct static pressure (Pressures  AIR.P  SP)
is above the configurable SP Low Alert Limit (Configura-
tion  IAQ  ALLM  SP.H) for 5 minutes, then the alert will
occur. The unit will continue to run and the alert will automati-
cally reset.
T312 (Building Static Pressure Below Limit)
If the unit is configured to use modulating power exhaust, then
a building static pressure limit can be configured using the BP
Low Alert Limit (Configuration  IAQ  ALLM  BP.L). If
the measured pressure (Pressures  AIR.P  BP) is below the
limit for 5 minutes then the alert will occur.
T313 (Building Static Pressure Above Limit)
If the unit is configured to use modulating power exhaust, then
a building static pressure limit can be configured using the BP
HI Alert Limit (Configuration  IAQ  ALLM  BP.H). If the
130
Alert Limit (Configuration 
duct static pressure
for
(Pres-