Carrier 69NT40-561-399 Operation And Service Manual page 79

AL21 CONTROL CIRCUIT FUSE (F1/F2)
Cause: One of the 18 VAC controller fuses (F1/F2) is open. Refer to Cd08.
Component
Corrective Action Replace defective sensor(s)
Component
Corrective Action Repair as needed.
Component
Corrective Action Replace controller, refer to Controller Service
AL22 EVAPORATOR IP
Cause: Evaporator motor internal protector (IP) is open.
Component
Corrective Action Replace defective evaporator fan motor, refer to EVAPORATOR
AL23 LOSS OF PHASE B
Cause: Controller fails to detect current draw.
Component
Corrective Action Correct power source as required.
AL24 COMPRESSOR IP
Cause: Compressor internal protector (IP) is open.
Component
Corrective Action Monitor unit, if alarm remains active or is repetitive replace the com-
System Sensors
Troubleshooting Check system sensors for short to ground.
Wiring
Troubleshooting Check wiring for short to ground.
Controller
Troubleshooting Controller may have an internal short.
Evaporator Motor
Troubleshooting Shut down unit, disconnect power, & check Evaporator Motor IP at
plug connection pins 4 & 6.
FAN MOTOR Service
Incoming Power
Troubleshooting Check incoming power source.
Compressor
Troubleshooting Shut down unit disconnect power, & check resistance of compressor
windings at contactor T1-T2, T2-T3.
pressor at the next available opportunity, refer to COMPRESSOR
Service
Section 7.14.
Section 7.8.
4–45
Section 7.24.
T-365