Carrier 69NT40-561-399 Operation And Service Manual page 77

AL18 DISCHARGE PRESSURE HIGH
Cause: Discharge pressure is over the maximum for 10 minutes within the last hour.
Component
Corrective Action Open Liquid Line Service Valve as needed.
Component
Corrective Action Replace the filter drier if needed, refer to FILTER DRIER Service
Component
Corrective Action Correct as required.
Component
Corrective Action Replace DPT if defective.
Component
Corrective Action Correct as required, refer to Refrigerant Charge
Component
Corrective Action Correct as required, refer to Refrigerant Charge
Restrictions in the refrigeration system.
Troubleshooting Ensure Liquid Line Service Valve is fully open.
Filter Drier
Troubleshooting Check the filter drier, if it is iced up or very cold it indicates that the
filter drier needs replacement.
Section
Condenser Fan
Troubleshooting Check Condenser Fan for proper operation.
Discharge Pressure Transducer (DPT)
Troubleshooting Confirm accurate DPT pressure readings, refer to MANIFOLD
GAUGE SET
Non-condensables in the refrigeration system.
Troubleshooting With the unit off allow system to stabilize to ambient temperature.
Check system pressure against PT Chart for 134a, refer to
4.
Refrigerant
Troubleshooting Check refrigerant level.
7.12.
Section 7.2.
4–43
Table 7–
Section 7.7.1.
Section 7.7.1.
T-365