Carrier 48PG03-16 Controls, Start-Up, Operation, Service And Troubleshooting Instructions page 80

2. Compressor internal protection is open.
3. Wiring error. A wiring error might not allow the
compressor to start.
To check out alerts T051, T052, T055, and T059:
1. Turn on the compressor in question using Service Test
mode. If the compressor does not start, then most likely
the problem is one of the following: HPS open, open
internal protection, incorrect safety wiring, or incorrect
compressor wiring.
2. If the compressor starts, verify that the indoor and outdoor
fans are operating properly.
3. If the CS is always detecting current, then verify that the
compressor is on. If the compressor is on, check the
contactor and the relay on the MBB. If the compressor is
off and there is no current, verify CS wiring and replace if
necessary.
4. Return to Normal mode and observe compressor operation
to verify that compressor current sensor is working and
condenser fans are energized after compressor starts.
Alert Codes T051, T052, T055 and T059 (Current Detected
After Turnoff)
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 control 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 Off.
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. Return to Normal mode and observe compressor operation
to verify that compressor current sensor is working and
condenser fans are energized after compressor starts.
Alert Codes T064, T065 and T080 (Condensing Temp.
Failure)
Alert codes T064, T065, and T080 are 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 fail, then circuit
shutdown alarm will occur also. 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 T073 (Outdoor Air Temp. 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 all units, if
both SCT and OAT fail, then circuit shutdown alarm will also
occur. For economizer equipped units, the economizer will not
operate to provide cooling. The economizer will still operate for
ventilation. For units without Humidi-MiZer™ system, the
control will use condenser temperatures for outdoor fan control.
For Humidi-MiZer system equipped units, the Reheat2 mode will
operate at fan level 1. For units with CCH crankcase heat relay
control, the crankcase heat relay will be turned on if any
compressor is off. 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 Temp. 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 Temp. 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. There is no control action as a
result of 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. Check sensor and wiring. This
alert clears automatically.
Alert Code T080 (Condensing 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 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, T103, and T104 (Current Sensor Failure)
Alert codes T102, T103, and T104 are for compressors A1 and
A2, B1, 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 cannot be resolved and the CS
board must be replaced, the CS board can be temporarily disabled
while securing a replaced board. A CS board is disabled by
setting the corresponding
(Configuration→COOL→CIR.A→CS.A1, CS.B1 or CS.C1).
Alert Codes T110, T111, T140 (Loss of Charge)
Alert codes T110, T111, and T140 are for circuits A, B and C,
respectively. These alerts occur 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. These alerts only occur when the
compressor is OFF because the low refrigerant pressure alarms
(alerts T133, T134 and T141) handle this situation when the
compressor is operating.
Alert Codes T126, T127, T142 (High Refrigerant Pressure)
Alert codes T126, T127, and T142 are for circuits A, B, and C,
respectively. These alerts occur when alerts T051, T055, or T059
are active while the appropriate condensing temperature is greater
than 150_F. These alerts 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 Alerts T051, T055 and T059
for diagnostic procedure.
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configuration to DISABLE