Carrier 48LC 04 Controls, Start-Up, Operation And Troubleshooting page 28

Alert Codes T051 (with Current Sensor)
This alert can only be activated if Current Sensing A1 is enabled
(Configuration COOL CS.A1 = Enabled). There are 4 different
texts for the alert code. There are two different alerts which have
corresponding test mode alerts indicated with "Service Test" in the
expanded text. Pressing enter and esc on the marquee or navigator to
expand the T051 alert will show you one of the below alerts. Make
sure the expanded text is read correctly before troubleshooting.
S Compressor Safety Trip
This alert occurs when the Current Sensor (CS) does not detect
compressor current during compressor operation. When this occurs,
the control turns off the compressor and logs a strike for the circuit.
This alert resets automatically. The possible causes are: high-pressure
switch (HPS) open, Condensate overflow switch (COFS) open,
compressor internal protection is open, or a wiring error (a wiring
error might not allow the compressor to start). The HPS and optional
COFS are wired in series with compressor relays on the MBB. If one
of these opens during compressor operation, the compressor stops
causing the control to activate this alert.
S Compressor Detected After Turnoff
This alert occurs when the Current Sensor (CS) detects current when
the compressor should be off. When this occurs, the control turns off
all of the compressor relays, stays in cooling mode and keeps the
indoor fan on. Use the Scrolling Marquee to reset the alert. The
possible causes are a welded contactor, frozen compressor relay on
MBB, or adverse conditions.
Alert Code T064 - - Circuit Saturated Condensing Temp
Thermistor Failure
This alert occurs when the temperature is outside the range –40_ to
240_F (–40_ to 116_C). The cause of the alert is usually a faulty
thermistor, a shorted or open thermistor caused by a wiring error,
or a loose connection.
Alert Code T066 - - Circuit Saturated Suction Temperature
Thermistor Failure
This alert occurs when the unit's suction transducers are turned off
internally. Cooling will not operate. This is usually due to a
network force on a non exposed CCN point. Reload factory
defaults or reinstall software on the MBB. Consult the network
manager if alert continues.
Alert Code T073 - - Outdoor Air Temperature Thermistor
Failure
This alert occurs when the temperature is outside the range –40_ to
240_F (–40_ to 116_C). For all units, all ambient temperature
lockout limits for cooling and heating are ignored. For economizer
equipped units, the economizer will not operate to provide cooling.
The economizer will still operate for ventilation. This alert resets
automatically. The cause of the alert is usually a faulty thermistor, a
shorted or open thermistor caused by a wiring error, or a loose
connection.
Alert Code T074 - - Space Temperature Thermistor Failure
This alert occurs when the temperature is outside the range –40_ to
240_F (–40_ to 116_C). This alert will only occur if the unit
control type is configured for Space Sensor (versus Thermostat).
Cooling and heating will not operate. For economizer equipped
units, the economizer will still operate for ventilation. This alert
resets automatically. The cause of the alert is usually a faulty
thermistor in the T- -55, T- -56, or T- -58 device, a shorted or open
thermistor caused by a wiring error, or a loose connection.
Alert Code T075 - - Supply Air Temperature Thermistor Failure
This alert occurs when the temperature is outside the range –40_ to
240_F (–40_ to 116_C). Economizer cooling and adaptive
compressor staging cannot occur while this alarm is active. This
alert resets automatically. The cause of the alert is usually a faulty
thermistor, 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 will only occur if the unit is
configured for a return air sensor. Economizer differential dry bulb
control will not be allowed during this alert. This alert resets
automatically. The cause of the alert is usually a faulty thermistor, a
shorted or open thermistor caused by a wiring error, or a loose
connection.
Alert Code T077 - - Space Relative Humidity Sensor Failure
This alert occurs when the input is less than 3.5 mA and the sensor
is configured as installed. If a humidistat is not installed, then
dehumidification will not be functional. Check sensor and wiring.
This alert clears automatically.
NOTE:
An ECB must be installed to use the space relative
humidity sensor.
Alert Codes T092 – Circuit Suction Pressure Transducer
Failure
This alert occurs when the board does not properly read the
transducer voltage. A circuit cannot run when this alert is active.
Use the Scrolling Marquee to reset the alarm. The cause of the alert
is usually a faulty transducer, faulty 5- -v power supply, or a loose
connection.
Alert Codes T102 - Compressor Current Sensor Failure
This alert can only occur if the unit is configured to have
compressor current sensor (Configuration→COOL→CS.A1).
This is not factory installed so would have to be installed in the
field and configured accordingly. This alert occurs when the output
of the current sensor (CS) is a constant high value. This alert resets
automatically. The cause of the alert is a wiring error, a loose
connection, or when configured to have the sensors when they are
not actually installed. If the problem cannot be resolved and the CS
board must be replaced, the CS board can be disabled while
securing a replaced board. A CS board is disabled by setting the
corresponding configuration to DISABLE.
Alert Codes T110 – Circuit Loss of Charge
This alert has "Service Test" text that will be displayed if the alert
occurred during service test. This alert occurs when the compressor
is OFF and the suction pressure is less than 5 psig and OAT is
greater than –5_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 faulty suction pressure. This alert only
occurs when the compressor is OFF because the low refrigerant
pressure alarms (alert T133) handle this situation when the
compressor is operating.
Alert Codes T126 - - Circuit High Discharge Pressure
This alert has"Service Test" text that will be displayed if the alert
occurred during service test. This alert occurs when alert T051 is
active while the appropriate condensing temperature is greater than
150_F. This alert reset automatically. The cause of the alert is
usually an overcharged system, high outdoor ambient temperature
coupled with dirty outdoor coil, plugged filter drier, or a faulty
high- -pressure switch. See Alert T051for diagnostic procedure.
Alert Codes T133 - - Circuit Low Refrigerant Pressure
This alert has "Service Test" text that will be displayed if the alert
occurred during service test. This alert occurs when the compressor
is operating and the evaporating temperature (converted from the
suction pressure) is less than configured low suction control levels,
ConfigurationCOOLSSTSST.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 4 minutes), or SST.3 (for 3 minutes when using the
economizer and 1.5 minutes when not using the economizer) for
the alert to occur. When the outdoor temperature is less than 40_F,
the above values are reduced 1_F for every 2_F the OAT is below
40_F. An alert will also occur if the circuit SST value is less than
SST.3 –5_F for 20 seconds and the outdoor temperature is above
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