Carrier 69NT40-541-505 Operation And Service Manual page 62

AL12 EVAPORATOR FAN 2 IP
Cause: Alarm 12 is triggered when configured for single evap operation and KB10 sensed high.
Component
Corrective Action AL11 is triggered off when KB10 sensed low.
AL15 LOSS OF COOLING
Cause: AL15 is triggered 30 minutes after the completion of a controller initiated probe check defrost if
Supply Temperature is more than 0.25°C (0.45°F) above set point. Refer to
Component
Corrective Action Refer to Refrigerant Charge,
AL20 CONTROL CONTACTOR FUSE (F3)
Cause: Control power fuse (F3A or F3B) is open.
Component
Corrective Action Replace the defective coil.
Component
Corrective Action Replace the defective coil.
Component
Corrective Action Refer to Controller Service
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Evaporator Fan 2
Troubleshooting The unit will suspend probe check diagnostic logic and disable the probe
check portion of defrost cycle.
Refrigerant Level
Troubleshooting Power cycle the unit.
Power cycle the unit.
Check F3A, if the fuse is open:
Troubleshooting Check PA, PB, CH coils for short to ground, if short is found:
Replace the fuse.
Check F3B, if the fuse is open:
Troubleshooting Check CF, ES, EF, HR coils for short to ground, if short is found, coil is de-
fective.
Replace the fuse.
Check Voltage at the output of F3A and F3B:
Troubleshooting If voltage is present at both F3A and F3B, it indicates a defective micropro-
cessor.
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Section 7.7
Section 7.20.
4–32
Section 4.3.17.