Carrier 69NT40-561-300, Operation And Service Manual

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