122
strike is tied to the circuit going off entirely, not reducing
capacity and recovering. Therefore it is possible that multiple
P126 and P127 alerts may be stored in alarm history but not
broadcast.
T128 (Digital Scroll High Discharge Temperature Alert)
A128 (Digital Scroll High Discharge Temperature Alarm)
— This alert/alarm is for units with a digital scroll compressor
only. The digital scroll compressor is equipped with a tempera-
ture thermistor that is attached to the discharge line of the
compressor.
The alert occurs when the discharge temperature thermistor
has measured a temperature above 268 F or the thermistor is
short circuited. The digital scroll compressor will be shut down
and alert T128 will be generated. The compressor will be al-
lowed to restart after a 30-minute delay and after the thermistor
temperature is below 250 F.
If five high discharge temperature alerts have occurred
within four hours, alarm A128 will be generated which will ne-
cessitate a manual reset to start the compressor.
T130 (Circuit A Filter Drier Alert)
T131 (Circuit B Filter Drier Alert) — Alert codes 130 and
131 are for circuits A and B respectively. These alerts occur
when a filter drier test has been run and pressure difference
DP.A-LP.A (or DP.B-LP.B) on the corresponding circuit is out-
side of ± Configuration
IAQ
PROG
AC.FD. This result
typically indicates the filter drier should be changed. The alert
will automatically clear when the test is re-run and the pressure
difference is within ± AC.FD. The cause of the alert is usually
dirty filter drier.
A140 (Reverse Rotation Detected)
— This alarm performs a
check for correct compressor rotation upon power up of the
unit. The method for detecting correct rotation is based on the
assumption that there will be a drop in suction pressure upon a
compressor start if the compressor is rotating in the correct
direction.
A test is made once, on power up, for suction pressure
change on the first compressor of the first circuit to start.
Reverse rotation is determined by measuring suction pres-
sure at 3 points in time:
• 5 seconds prior to compressor start.
• At the instant the compressor starts.
• 5 seconds after the compressor starts.
The rate of suction pressure change from 5 seconds prior to
compressor start to compressor start (rate prior) is compared to
the rate of suction pressure change from compressor start to 5
seconds after compressor start (rate after).
If (rate after) is less than (rate prior minus 1.25), alarm
A140 is generated.
This alarm will disable mechanical cooling and will require
a manual reset. This alarm may be disabled once the reverse ro-
tation check has been verified by setting Configuration
COOL
RR.VF = Yes.
It is important to note that in Service Test mode, reverse ro-
tation is checked on every compressor start.
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.
A169 (Expansion Valve Control Board Comm Failure)
—
Cooling is disabled until communication with the EXV control
board is re-established. Recovery is automatic. Reason for fail-
ure may be due to incorrect wiring, power loss to the control
board, or damage to the RS-485 drivers on the LEN bus.
T170 (Compressor Expansion Board Comm Failure)
—
Compressors A3, A4, B3 and B4 are disabled until communi-
cation with the CEB control board is re-established. Recovery
is automatic. Reason for failure may be due to incorrect wiring,
power loss to the control board, or damage to the RS-485 driv-
ers on the LEN bus.
A171 (Staged Gas Control Board Comm Failure)
— Staged
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 drivers 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 (RXB Board Communication Failure)
— As the RXB
board is integral to all P 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 RXB board, or damage to the RS-485 drivers
on the LEN bus.
A174 (EXB Board Communication Failure)
— The EXB
board is responsible for building pressure control. Building
Pressure control configurations that require this board will
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