Carrier 69NT40-541-505 Operation And Service Manual page 67

AL59
Cause: Heat Termination Thermostat (HTT) is open.
AL60
Cause: Failure of the Defrost Temperature Sensor (DTS) to open.
AL61
Cause: Improper current draw during heat or defrost mode.
AL63
Cause: Unit operating above current limit.
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HEATER TERMINATION THERMOSTAT (HTT)
Component Alarm 59 is triggered by the opening of the Heat Termination Thermostat
(HTT) and will result in the disabling of the heater.
Troubleshooting Check for 24 volts at test point TP10, if no voltage at TP10 after unit has
reached set point HTT is open.
Corrective Action Replace HTT if defective.
DEFROST TEMPERATURE SENSOR (DTS)
Component Defrost Temperature Sensor (DTS)
Troubleshooting Test the DTS; refer to Sensor Checkout Procedure
Corrective Action Replace the DTS if defective, refer to Sensor Replacement
HEATER CURRENT DRAW FAULT
Component Heater(s)
Troubleshooting While in heat or defrost mode, check for proper current draw at heater con-
tactors, refer to Electrical Data
Corrective Action Replace heater(s) if defective, refer to
moval and Replacement.
Component Contactor
Troubleshooting Check voltage at heater contactor on the heater side. If no voltage present:
Corrective Action Replace heater contact or if defective.
CURRENT LIMIT
Component Refrigeration System
Troubleshooting Check unit for air flow restrictions.
Corrective Action Clean or remove any debris from coils.
Component Refrigeration System
Troubleshooting Check unit for proper operation.
Corrective Action Repair as needed.
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Section 3.3.
Section 7.13
4–37
Section 7.21.1.
Section 7.21.2.
Evaporator Heater Re-
T-368