99
T136 (Compressor A1 Low Differential Pressure)
T137 (Compressor A2 Low Differential Pressure)
T138 (Compressor B1 Low Differential Pressure)
T139 (Compressor B2 Low Differential Pressure) — If the
pressure differential between the discharge and suction pres-
sure transducers is less than 50 psig for more than 15 minutes
when the circuit is running, an alert will be issued and the cir-
cuit shut down. Any compressor that is currently on at the time
of the alert will have its own individual alarm sent. Reset is
manual.
T140 (Circ A Max Diff Operating Press Exceeded)
T141 (Circ B Max Diff Operating Press Exceeded) — De-
pending on the compressor loading, after 5 minutes of opera-
tion if the discharge versus suction pressure ratios exceed
the curves in Fig. 14, then all compressors in that circuit are
stopped and the alert tripped. Reset is manual.
A150 (Unit is in Emergency Stop) — If the CCN point name
“EMSTOP” in the System table is set to emergency stop, the
unit will shut down immediately and broadcast an alarm back
to the CCN indicating that the unit is down. This alarm will
clear when the variable is set back to “enable”.
A152 (Unit Down Due to Failure) — This alarm occurs
whenever both cooling circuits are unavailable to cool. Me-
chanical cooling is impossible due to a failure in the system ex-
plained through other current alarms.
Possible problems are:
• plenum pressure switch trips on a return fan tracking unit
• the supply fan status alarms have been instructed to shut
down the unit
• both circuits incapable of cooling due to multiple alerts of
compressors and/or pressure alerts
• a hardware failure of the main board's analog to digital con-
verter or EEPROM chip
• a critical storage failure in EEPROM has rendered the unit
inoperable
• the unit is configured for inlet guide vanes and the actuator
controlling the vanes is in fault.
Reset is automatic.
T153 (Real Time Clock Hardware Failure) — The RTC
clock chip on the MBB is not responding. Recovery is auto-
matic but typically board replacement may be necessary.
A154 (Serial EEPROM Hardware Failure) — The unit will
be completely shut down. The serial EEPROM chip on the
MBB which stores the unit's configurations is not responding.
Recovery is automatic but typically board replacement is
necessary.
T155 (Serial EEPROM Storage Failure Error) — Configura-
tion data in the serial EEPROM chip can not be verified which
may mean MBB replacement. It is possible a re-initialization
of the database or particular storage area(s) may clean up this
problem. Reset is automatic.
A156 (Critical Serial EEPROM Storage Fail Error) — The
unit is completely shut down. Critical configuration data in the
serial EEPROM chip can not be verified which may mean
MBB replacement. Recovery is automatic but typically board
replacement is necessary.
NOTE: The machine will shut down. This may happen after
downloading via the CCN if the device code was corrupted.
Try downloading again or use the LEN connection to
download.
A157 (A/D Hardware Failure) — The unit will be completely
shut down. The analog to digital conversion chip on the MBB
has failed. Recovery is automatic but typically board replace-
ment is necessary.
A171 (Staged Gas Control Board Comm Failure) — Staged
Gas Heating is disabled until communication with the staged
gas control board is re-established. Recovery is automatic.
Reason for failure may be due to incorrect wiring, power loss
to the staged gas control board, or damage to the RS-485 driv-
ers on the LEN bus.
T172 (Control Expansion Module Comm Failure) — Any
function associated with a sensor configured for use that re-
sides on the controls expansion module will be disabled until
communication is re-established. Recovery is automatic. Rea-
son for failure may be due to incorrect wiring, power loss to the
control expansion module, or damage to the RS-485 drivers on
the LEN bus.
A173 (RCB Board Communication Failure) — As the RCB
board is integral to all Z series units, the error will cause a sys-
tem shutdown until communication is re-established. Recovery
is automatic. Reason for failure may be due to incorrect wiring,
power loss to the RCB board, or damage to the RS-485 drivers
on the LEN bus.
A174 (ECB Board Communication Failure) — The ECB
board is responsible for building pressure control. Building
Pressure control configurations that require this board will
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 ECB board, or dam-
age 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.
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 RCB 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
RCB 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