Carrier 69NT40-541-300, Operation And Service

Page: 63 / 152

T-318 3 − 31
Table 3-6 Controller Alarm Indications (Sheet 2 of 6)
Alarm Code Cause Components Troubleshooting Corrective Actions
AL21
Control Circuit
Fuse (F1/F2)
One of the 18 VAC
controller fuses
(F1/F2) is open. Refer
to Cd08.
System Sensors Check system sensors for
short to ground.
Replace defective
sensor(s)
Wiring Check wiring for short to
ground.
Repair as needed.
Controller Controller may have an
internal short.
Replace controller, refer
to Controller Service
Section 6.23.
AL22
Evaporator IP
Evaporator motor
internal protector (IP)
is open.
Evaporator Motor Shut down unit, disconnect
power, & check Evaporator
Motor IP at plug connection
pins 4 & 6.
Replace defective
evaporator fan motor,
refer to EVAPORATOR
FAN MOTOR Service
Section 6.16.
AL23
Loss of Phase
B
Controller fails to
detect current draw.
Incoming Power Check incoming power
source.
Correct power source as
required.
AL24
Compressor
IP
Compressor internal
protector (IP) is open.
Compressor Shut down unit disconnect
power, & check resistance
of compressor windings at
contactor T1 − T2, T2 − T3.
Monitor unit, if alarm
remains active or is
repetitive replace the
compressor at the next
available opportunity,
refer to COMPRESSOR
Service Section 6.8.
AL25
Condenser IP
Condenser fan motor
internal protector (IP)
is open.
Insufficient Air
Flow
Shut down unit and check
condenser fan for obstruc-
tions.
Remove obstructions.
Condenser Fan
Motor
Shut down unit, disconnect
power, & check Condenser
Fan Motor IP at plug con-
nection pins 1 & 2.
Replace defective
condenser fan motor,
refer to Condenser Fan
Motor Assembly
Service Section 6.11.
AL26
All Sensors
Failure:
Supply/Return
Probes
Sensors out of range. All sensors.
detected as out of
range
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 6.24.
AL27
Analog to
Digital
Accuracy
Failure
Controller AD
converter faulty.
Controller Power cycle the unit. If the
alarm persists, it indicates
a defective
microprocessor.
Replace defective
microprocessor, refer to
Controller Service
Section 6.23.