44 PFS 155C - 315C OM 135
PROBLEM POSSIBLE CAUSES POSSIBLE CORRECTIVE STEPS
High Discharge Pressure 1. Discharge shutoff valve partially closed 1. Open shutoff valve.
2. Noncondensables in the system 2. Purge the noncondensables from the condenser coil after
shutdown
3. Condenser water insufficient or temperature too high 3. Read temperature control or water regulating valve
Investigate ways to increase water supply
4. Fouled condenser tubes (water cooled condenser. 4. Clean. Dirty tube and fin surface (cooling tower)
5. System overcharged with refrigerant 5. Check for excessive subcooling above 30°F (-1 °C).
Remove excess charge.
6. Cooling tower is undersized. 6. Check cooling tower rating tables against the operation
7. High ambient conditions. 7. Check cooling tower rating tables against the operation
8. Air restrict on at cooling tower. 8. Remove obstructions near unit
Low Discharge Pressure 9. Cooling tower too large. 9. Check cooling tower rating tables
10. Faulty cooling tower temperature regulation 10. Check cooling tower control operation
11. Suction shutoff valve partially closed. 11. Open valve.
12. insufficient refrigerant in system. 12. Check for leaks. Repair and add charge.
13. Low suction pressure. 13. See corrective Steps for low suction pressure.
14. Low ambient condition. 14. Check cooling tower control operation
15. Compressor operating unloaded. 15. See corrective Steps for failure to load
Low Suction Pressure 16. Inadequate refrigerant charge quantity 16. Check liquid line sightglass Check unit for leaks.
17. Inadequate liquid to liquid injection at star 17. Repair and recharge to clear sightglass
18. Clogged liquid line filter dryer 18. Check pressure drop across filter dryer Replace cores.
19. Expansion valve malfunctioning. 19. Check expansion valve superheat and valve opening
position Replace valve only if certain valve is not working.
20. insufficient water flow to evaporator 20. Check water pressure drop across the evaporator and
adjust gpm
21. Water temperature leaving evaporator is too low. 21. Adjust water temperature to higher value.
22. Evaporator tubes fouled. 22. Inspect by removing water piping Clean chemically
23. Evaporator head ring gasket slippage 23. Low suction pressure and low superheat both present may
indicate an internal problem Consult factory.
High Suction Pressure 24. Excessive load - high water temperature 24. Reduce load or add additional equipment.
25. Superheat is too low. 25. Check superheat on MicroTech display. Check suction
line sensor installation and sensor.
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