Alarms And Alerts; Diagnostic Alarm Codes And Possible Causes - Carrier 48HG014 Controls Operation And Troubleshooting

Alarms and Alerts —
abnormal or fault conditions, and may cause either one circuit
or the entire unit to shut down. They are assigned code
numbers and descriptions as described below. The description
for an alarm can be viewed from the Scrolling Marquee display
by pressing
ESCAPE
while displaying the alarm code number. Be sure to expand the
description for each alert and alarm, because in some cases,
there are different possible descriptions for each number.
Table 27 contains a detailed description of each alarm and alert
code error and possible cause. Possible actions taken by the
electronic controls are:
• nothing
• adding a "strike" to the strike counter for a particular
circuit
• shutting down a circuit
• shutting down the unit.
When a "strike" is added, the circuit is shut down for
15 minutes. After 3 strikes, the circuit will be permanently shut
down until the alarms are reset via the Scrolling Marquee
display. More information concerning alarm handling can be
found in Alarm Handling on page 31.
DIAGNOSTIC ALARM
CAUSES
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Alert Codes 51, 55 and 59 (Compressor Safety) — Alert
codes 51, 55, and 59 are for compressors A1, B1, and C1, re-
spectively. These alerts occur when the Current Sensor (CS)
does not detect compressor current during compressor opera-
tion. When this occurs, the control turns off the compressor and
logs a strike for the respective circuit. These alerts reset
automatically.
The possible causes are:
1. High-pressure switch (HPS) open. The HPS-pressure
switch is wired in series with compressor relays on the
MBB. If the high-pressure switch opens during compres-
sor operation, the compressor stops, and the CS no longer
detects current, causing the control to activate this alert.
2. Compressor internal protection is open.
3. Wiring error. A wiring error might not allow the compres-
sor to start.
To check out alerts 51, 55 and 59:
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 in-
ternal protection, incorrect safety wiring, or incorrect
compressor wiring.
2. If the compressor starts, verify that the indoor and out-
door 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 con-
tactor 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 opera-
tion to verify that compressor current sensor is working
and condenser fans are energized after compressor starts.
Alert Codes 51, 55 and 59 (Current Detected After Turnoff)
— Alert codes 51, 55, and 59 are for compressors A1, 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 the compressor and logs a
strike for the respective circuit. Use the Scrolling Marquee to
reset the alert.
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Alarms and alerts are warnings of
and keys simultaneously
ENTER
CODES AND POSSIBLE
The possible causes are
1. Welded contactor.
2. Frozen compressor relay on MBB.
To check out alerts 51, 55 and 59:
1. Place the unit in Service Test Mode. All compressors
should be Off.
2. Verify that there is not 24V at the contactor coil. If there is
24V 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 opera-
tion to verify that compressor current sensor is working
and condenser fans are energized after compressor starts.
Alert Codes 64, 65 and 80 (Condensing Temp. Failure) —
Alert codes 64, 65, and 80 are for circuits A, B and C, respec-
tively. These alerts occur when the temperature is outside the
range –40 to 240 F (–40 to 116 C). When this occurs, the
control uses the outdoor temperature to control the outdoor
fans. If the outdoor temperature is greater than 40 F, the circuit
will run at Fan Level 2. If the outdoor temperature is less than
35 F, the circuits will run at Fan Level 1. If the outdoor-air sen-
sor is also bad, the circuit will be locked out, otherwise 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 73 (Outside Air Temp. Failure) — This alert occurs
when the temperature is outside the range –40 to 240 F (–40 to
116 C). 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 74 (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 is in Space Sensor
Mode. The unit will shut down if this alert occurs while in
Space Sensor mode. This alert resets automatically. The cause
of the alert is usually a faulty thermistor in the T55, T56, or
T58 device, a shorted or open thermistor caused by a wiring er-
ror, or a loose connection.
→
Alert Code 75 (Supply Air Temp. Failure) — This alert occurs
when the temperature is outside the range –40 to 240 F (–40 to
116 C). 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 80 (Condensing Temp. Failure) — See Alert 64.
Alert Codes 92, 93, 101 (Suction Pres. Trans. Failure) — Alert
codes 92, 93, and 101 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 102, 103, 104 (Current Sensor Failure) — Alert
codes 102, 103, and 104 are for compressors A1, B1, and C1,
respectively. These alerts occur when the output of the current
sensor (CS) is a constant high value. These alerts reset auto-
matically. The cause of the alert is a wiring error or a loose con-
nection. 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 set-
ting the corresponding configuration to DISABLE (CS.A1,
CS.B1 or CS.C1).
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