High Suction Pressure
refrigeration
Description
High suction pressure means suction pressure has been greater than 98 psig (6.7 bar) for more than 10 minutes, and the unit alarms only or shuts down and alarms if configured.
Activation Conditions
The refrigeration system is running and suction pressure has been greater than 98 psig (6.7 bar) for more than 10 minutes.
Unit Behavior
Alarm only or (if configured for shutdown) engine and unit shutdown and alarm.
Reset Conditions
Auto reset when suction pressure is less than 75 psig (5.1 bar) for five minutes and configured for Alarm Only, or Auto Reset after 15 minutes if configured as a Shutdown Alarm or, alarm may be manually reset via keypad or by turning the unit off, then back on again.
Corrective Actions
1. Check System Pressures: Install manifold gauge set and check and compare compressor discharge and suction pressures with those shown in Unit Data. Suction pressure must be above 3 psig (0.2 bar) and should be in the normal range for ambient and refrigerated compartment conditions. Refer to Section 1.9.12. 2. Check Compressor Drive Coupling: Verify that compressor coupling is intact and the compressor crankshaft is turning. Repair as required. 3. Check Refrigerant Charge: Refer to Section 1.7.2. 4. Perform Pretrip Check: Clear Active Alarm list, then run Pretrip and check for any new alarms. Any active alarms must be corrected and cleared before proceeding. 5. Check Compressor a. Perform Pump-Down Test. Refer to Section 1.8.1. Must hold a vacuum and not equalize in a short period of time. b. Cover condenser and build-up discharge pressure. Must be able to raise pressure to 400 psig (27.2 bar). c. Disassemble and inspect compressor valve plates, cylinder suction valves, cylinder discharge valves and pistons, etc. Must be intact, clean, and in good working order. Refer to Section 1.8. 6. Check Expansion Valve (EVXV) a. Visually inspect valve. Check coil is seated properly. b. Check valve. Refer to Section 1.9.9.