Carrier 69NT40-561-201, Operation & Service Manual, Page: 59 / 117

3 − 30 T-364
Table 3 − 6 Controller Alarm Indications (Sheet 5 of 8)
Alarm Code Cause Components Troubleshooting Corrective Actions
AL28
Low Suction
Pressure
Suction pressure too
low for normal
operation.
N/A Power cycle the unit. Resetting the unit may
correct problem, monitor
the unit.
Suction Pressure
Transducer (SPT)
Confirm accurate SPT
pressure readings, refer to
MANIFOLD GAUGE SET
Section 6.2.
Replace SPT if
defective.
Discharge
Pressure
Transducer (DPT)
Confirm accurate DPT
pressure readings, refer to
MANIFOLD GAUGE SET
Section 6.2.
Replace DPT if
defective.
AL29
(NOT USED)
AL50
Air Vent
Position
Sensor (VPS)
VPS Sensor out of
range.
Vent Position
Sensor (VPS)
Make sure VPS is secure. Manually tighten panel.
If the alarm persists,
replace the sensor or the
assembly.
Replace VPS.
AL51
EEPROM
Failure
Controller Memory
Failure
Controller Pressing the ENTER key
when “CLEAr” is displayed
will result in an attempt to
clear the alarm.
If action is successful (all
alarms are inactive),
alarm 51 will be reset.
Power cycle the unit. If the
alarm persists, it indicates
defective controller
memory.
Replace defective
controller, refer to
Controller Service
Section 6.21
AL52
EEPROM
Alarm List Full
Alarm list queue is full. Active Alarms Repair any alarms in the
queue that are active.
Indicated by “AA”.
Clear alarms, refer to
CONTROLLER
ALARMS Section 3.5.
AL53
Battery Pack
Failure
Battery voltage low Battery If this alarm occurs on start
up, allow a unit fitted with
rechargeable batteries to
operate for up to 24 hours
to charge rechargeable
batteries sufficiently. Once
fully charged, the alarm will
deactivate.
To clear the alarm press
ENTER and ALT simul-
taneously at the startup
of Cd19 (Battery Check).
If alarm persists, replace
the battery pack, refer to
Section 6.21.5 Battery
Replacement.
AL54
Primary
Supply Sensor
(STS)
Invalid Supply
Temperature Sensor
(STS) reading.
Supply
Temperature
Sensor (STS)
Perform Pre-trip P5: If P5 passes, no further
action is required.
If P5 fails, replace the
defective sensor as
determined by P5, refer
to TEMPERATURE
SENSOR Service
Section 6.22.