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A170 (Loss of Communication with the Compressor
Expansion Module) — This alarm indicates that there are
communications problems with the compressor expansion,
which is required for unit sizes 070 to 100. The alarm will auto-
matically reset.
A173 (Energy Management Module Communication Fail-
ure) — This alarm indicates that there are communications
problems with the energy management. All functions per-
formed by the EMM will stop, which can include demand lim-
it, reset and capacity input. The alarm will automatically reset.
T174 (4 to 20 mA Cooling Set point Input Failure)
— This
alert indicates a problem has been detected with cooling set
point 4 to 20 mA input. The input value is either less than 2 mA
or greater than 22 mA.
T176 (4 to 20 mA Reset Input Failure)
— This alert indi-
cates a problem has been detected with reset 4 to 20 mA input.
The input value is either less than 2 mA or greater than 22 mA.
The reset function will be disabled when this occurs.
T177 (4 to 20 mA Demand Limit Input Failure)
— This
alert indicates a problem has been detected with demand limit
4 to 20 mA input. The input value is either less than 2 mA or
greater than 22 mA. The reset function will be disabled when
this occurs.
A200 (Fan Status Switch 1 Failure)
T201 (Fan Status Switch 1 Failure)
T202 (Fan Status Switch 2 Failure) — This alarm or alert in-
dicates the fan status input 1 or 2 is open when the unit is ON.
The unit will be in an alert condition until the fan status switch
is closed. The alarm or alert is an automatic reset when the fan
status switch closes. The A200 alarm is for single circuit units.
T303 (Condenser Coil Maintenance Due)
— Coil Service
Countdown (C.L.DN) expired. Complete condenser coil clean-
ing and enter ‘YES’ for Coil Maintenance Done (C.L.MN)
item.
T500, T501, T502 (Current Sensor Board Failure — A xx
Circuit A)
T503, T504, T505 (Current Sensor Board Failure — B xx
Circuit B) — Alert codes 500, 501, 502, 503, 504, and 505 are
for compressors A1, A2, A3, B1, B2, and B3 respectively.
These alerts occur when the output of the current sensor (CS) is
a constant high value. These alerts reset automatically. If the
problem cannot be resolved, the CS board must be replaced.
Table 26 — Alarm and Alert Codes
LEGEND
ALARM/
ALERT CODE
ALARM OR
ALERT
DESCRIPTION WHY WAS THIS ALARM GENERATED?
ACTION TAKEN
BY CONTROL
RESET
METHOD
T048 Alert
Circuit A Compressor
Availability Alert
Two compressors on circuit failed Circuit shut down Manual
T049 Alert
Circuit B Compressor
Availability Alert
Two compressors on circuit failed Circuit shut down Manual
T051, T052, T053 Alert
Circuit A
Compressor A1,A2,A3
Failure
Respective current sensor board (CSB)
feedback signal does not match relay state
Respective compressor shut
down in Circuit A.
Manual
T055, T056, T057 Alert
Circuit B
Compressor B1,B2,B3
Failure
Respective current sensor board (CSB)
feedback signal does not match relay state
Respective compressor shut
down in Circuit B.
Manual
A051, A052, A053 Alarm
Circuit A
Compressor A1,A2,A3
Failure
Respective current sensor board (CSB)
feedback signal is ON when the compressor
should be off
Unit shut down Manual
A055, A056, A057 Alarm
Circuit B
Compressor B1,B2,B3
Failure
Respective current sensor board (CSB)
feedback signal is ON when the compressor
should be off
Unit shut down Manual
A060 Alarm
Supply Air
Thermistor Failure
Thermistor outside range of –40 to 245 F
(–40 to 118 C)
Unit shut down Automatic
A060 Alarm
Supply Air Temperature
Update not received
Temperature not updated during 3 minutes Unit shut down Automatic
A061 Alarm
Return Air
Thermistor Failure
Thermistor outside range of –40 to 245 F
(–40 to 118 C)
Unit shut down Automatic
A061 Alarm
Return Air Temperature
Update not received
Temperature not updated during 3 minutes Unit shut down Automatic
T068 Alert
Circuit A Return Gas
Thermistor Failure
Thermistor is outside range of –40 to 245 F
(–40 to 118 C)
Circuit shut down Automatic
T069 Alert
Circuit B Return Gas
Thermistor Failure
Thermistor is outside range of –40 to 245 F
(–40 to 118 C)
Circuit shut down Automatic
T073 Alert
Outside Air
Thermistor Failure
Thermistor outside range of –40 to 245 F
(–40 to 118 C)
Temperature reset disabled.
Unit runs under normal
control/set points.
Automatic
T074 Alert
Space Temperature
Thermistor Failure
Thermistor outside range of –40 to 245 F
(–40 to 118 C)
Temperature reset disabled.
Unit runs under normal
control/set points.
Automatic
T090 Alert
Circuit A Discharge Pres-
sure Transducer Failure
The pressure is outside the range of
0.0 to 667.0 psig
Circuit A shut down Automatic
T091 Alert
Circuit B Discharge Pres-
sure Transducer Failure
The pressure is outside the range of
0.0 to 667.0 psig
Circuit B shut down Automatic
T092 Alert
Circuit A Suction Pressure
Transducer Failure
The pressure is outside the range of
0.0 to 420.0 psig
Circuit A shut down Automatic
T093 Alert
Circuit B Suction Pressure
Transducer Failure
The pressure is outside the range of
0.0 to 420.0 psig
Circuit B shut down Automatic
T094 Alert
Discharge Gas
Thermistor Failure
Discharge thermistor (DTT) is
either open or shorted
Digital compressor shut down. Automatic
CCN — Carrier Comfort Network
®
LWT — Leaving Fluid Temperature
CSB — Current Sensor Board MBB — Main Base Board
CXB — Compressor Expansion Module SCT — Saturated Condensing Temperature
DTT — Discharge Temperature Thermistor SST — Saturated Suction Temperature
EEPROM — Electrically Erasable Programmable
Read-Only Memory
TSTAT — Thermostat
EMM — Energy Management Module