Specifications

andthereisnocurrent,verilyCSwiringandreplaceif
necessary.
4. ReturntoNormalmodeandobsmTecompressoropera-
tiontoverifythatcompressorcurrentsensorisworking
andcoMenser/hnsareenergizedaftercompressorstarts.
Alert Codes T051. T052, T055 and T059 (Current Detected
After TurnofI) Alert codes T051, T052, T055, and T059
are for compressors A1, A2, B1, and C1, respectively. These
alerts occur when the Current Sensor (CS) detects current
when the compressor should be off'.When this occurs, the con-
trol turns off all of the compressors. Use the Scrolling Marquee
to reset the alert.
The possible causes are
1. Welded contactor.
2. Frozen compressor relay on MBB.
To check out alerts T051, T052, T055, and T059:
1. Place the unit in Service Test mode. All compressors
should be Ofl_
2. Verify that there is not 24 v at the contactor coil. If there is
24 v at the contactor, check relay on MBB and wiring.
3. Check for welded contactor.
4. Verify CS wiring.
5. Remm to Normal mode and obsm_e compressor opera-
tion to verify that compressor current sensor is working
and coMenser i_ansare eneNized after compressor starts.
Alert Codes T064, T065 and T080 (Condensin_ Temp. Fail-
ure) Alert codes T064, T065, and T080 axe for circuits A, B
and C, respectively. These alerts occur when the temperature is
outside the range _40 to 240 F (40 to 116 C). When this
occurs, the control will use only the outdoor temperature to
control the outdoor fans. If both the SCT and OAT tail, then
circuit shutdown alarm will occur also. The cause of the alert is
usually a thulty thermistor, a shorted or open thermistor caused
by a wiring error, or a loose connection.
Alert Code T073 (Outdoor Air Temp. Failure) This alert oc-
curs when the temperature is outside the range _40 to 240 F
( 40 to 116 C). For all units, all ambient temperature lockout
fimits for cooling and heating are ignored. For all units, if both
SCT and OAT tail, then circuit shutdown atann will also occur.
For economizer equipped units, the economizer will not
operate to provide cooling. The economizer wilt still operate
for ventilation. For units without Humidi-MiZer TM system, the
control will use coMenser temperatures for outdoor tan con-
trol. For Humidi-MiZer system equipped units, the Reheat2
mode will operate at tan level 1.For units with CCH crankcase
heat relay control, the cnmkcase heat relay will be turned on if
any compressor is off" This alert resets automatically. The
cause of the alert is usually a thulty thermistor, a shorted or
open thermistor caused by a wiring error, or a loose connection.
Alert Code T074 (Space Temp. Failure) This alert occurs
when the temperature is outside the range _40 to 240 F @40 to
116 C). This alert will only occm if the unit control type is con-
fi_red for Space Sensor &ersus Thermostat). Cooling and
heating will not operate. For economizer equipped units, the
economizer will still operate tbr ventilation. This alert resets
automatically. The cause of the alert is usually a thulty
thermistor in the T-55, T-56, or T-58 device, a shorted or open
thermistor caused by a wiring erroi; or a loose connection.
Alert Code T075 (Supply Air Temp. Failure) This alert oc-
curs when the temperature is outside the range _40 to 240 F
(40 to 116 C). Economizer cooling and adaptive compressor
staNng cannot occur while this atann is active. This alert resets
automatically. The cause of the alert is usually a thulty ther-
mistor, a shorted or open thermistor caused by a wiring error, or
a loose connection.
Alert Code T076 (Return Air Thermistor Failure) This
alert occurs when the temperature is outside the range _40 to
240 F (40 to 116 C). This alert wilt only occur if the unit is
confimlred for a return air sensor. There is no control action as
a result of this alert. This alert resets automatically. The cause
of the alert is usually a thulty thennistoi; a shorted or open
thennistor caused by a wiring error, or a loose connection.
Alert Code T077 (Space Relative Humidit¥ Sensor Failure)
This alert occurs when the input is less than 3.5 mA and the
sensor is configured as installed. Check sensor and wiring. This
alert clears automatically.
Alert Code T080 (Condensin_ Temp. Failure) See Alert
T064.
Alert Codes T092, T093, T101 (Suction Pressure Transducer
Failure) Alert codes T092, T093, and T101 are for circuits
A, B and C, respectively. These alerts occur when the pressure
is outside the range 0.5 to 134.5 psig. A circuit cannot mn
when this alert is active. Use the Scrolling Marquee to reset the
alarm. The cause of the alert is usually a thulty transducer,
thulty 5-v power supply, or a loose connection.
Alert Codes T 102, T 103, and T 104 (Current Sensor Failure)
Alert codes T102, T103, and T104 are for compressors A1
and A2, B 1,and C1, respectively. These alerts occur when the
output of the current sensor (CS) is a constant high value.
These alerts reset automatically. The cause of the alert is a
wiring error or a loose connection. If the problem calmot be
resolved and the CS board must be replaced, the CS board can
be temporm-ily disabled while securing a replaced board. A CS
board is disabled by setting the corresponding configuration to
DISABLE ((bnfiguration _'OOL _IR.A _'S.A1, CS.B1
or CS. (7).
Alert Codes Tll0, Tl11, T140 (Loss of Charge) Alert
codes Tll0, Tlll, and T140 are for circuits A, B and C, re-
spectively. These alerts occur when the compressor is OFF and
the suction pressure is less than 5 psig and OAT is meater than
F for 1 continuous minute. Use the Scrolling Marquee to
reset the alert. The cause of the alert is usually low refrigerant
pressure or a thulty suction pressure. These alerts only occur
when the compressor is OFF because the low refiigerant pres-
sure alarms (alerts T133, T134 and T141) handle this situation
when the compressor is operating.
Alert Codes T126. T127, T142 (High Refi-i_erant Pressure)
Alert codes T126, T127, and T142 axe for circuits A, B, and C,
respectively. These alerts occur when alerts T051, T055, or
T059 are active while the appropriate condensing temperature
is reeater than 150 F. These alerts reset automatically. The
cause of the alert is usually an overcharged system, high out-
door ambient temperature coupled with dirty outdoor coil,
plugged filter drier, or a thulty high-pressure switch. See Alerts
T051, T055 and T059 for diagnostic procedure.
Alert Codes T133, T134, T141 (Low Refiigerant Pressure)
Alert codes T133, T134, and T141 are for circuits A, B and C,
respectively. These alerts occur when the compressor is operat-
ing and the evaporating temperature (converted fiom the suc-
tion pressure) is less than confi_red low suction control levels,
(bnfiguration_DOL--_gST--agSr.1 (Low Suction
Level 1) or SST.2 (Low Suction Level 2) or SST.3 (Low
Suction Level 3). The circuit SST value must be less than
SST.1 for 5 minutes, SST.2 for 3 minutes, or SST.3 for 1.5mth-
utes for the alert to occur. When the outdoor temperature is less
than 40 E the above values are reduced by an ofl;et that scales
bewveen 0 and 20 as the outdoor temperature goes from 40 to
0° F.An alert will also occur if the circuit SST value is less than
SST.3 5 F for 20 seconds. These alerts cause a strike for the
respective circuit. These alerts will activate when the coil
becomes tiosted. However, during the 15-minute reset period,
the coils will thaw and strike should clear at restart if there is
nothing else ,aTongwith the circuit. The alert resets automatical-
ly. The cause of the alert is usually low refiigerant charge, dirty
filters, evaporator fan operating bac_vards, loose or broken
belt, plugged filter driei; thulty transducer, excessively cold
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