High Discharge Pressure
refrigeration
Description
During Cool Pretrip Test #4, discharge pressure is higher than normal, and the unit gives an alarm only.
Activation Conditions
This alarm is generated during Test #4 in Cool Pretrip. Discharge pressure is higher than normal. (“Normal” discharge pressure for systems operating in Cool mode can be estimated by taking the temperature of the air entering the condenser coil (Ambient Air Temperature AAT) and adding 30°F (16.6° C) to it, then looking at a pressure temperature chart-see Table 1–3 for the corresponding pressure.)
Unit Behavior
Alarm Only
Reset Conditions
Auto reset if Pretrip is started again, or Alarm may be manually reset using the display mounted keys or by turning the unit off, then back on again.
Corrective Actions
1. Check Wiring to CDP and CSP a. Verify that correct wires are connected to each transducer. Plugs to transducers are the same. The correct wire plug must be connected to the proper transducer. The CDP connector is identified with a red tape band while the CSP connector is identified with a blue band. b. Verify that correct transducer is installed in each position. Mechanical connections are the same. The CDT should have a red dot on it while the CST has a blue dot. 2. Check System Pressures: Install manifold gauge set and check and compare compressor discharge and suction pressures with those shown in Unit Data. Refer to Section 1.9.12 for instruction on comparison. 3. Check High Side Operating Conditions: Refer to procedure for alarm 00013 High Discharge Pressure. Alarm condition must be corrected and the alarm cleared to continue.