2201Q4JE-MY-C9-N_2018.01.
Chapter 6 Troubleshooting
Compound 2-stage Screw Compressor 4032**C
6-5
06: Unusually high pressure (continued)
Direct cause
Root cause
Action
Discharge pressure
detection function is
defective.
Failure of high pressure
protection device, pressure
sensor, relay, etc.
Identify defective devices, investigate
causes of failure and take necessary
actions.
Then, replace failed device(s).
clogging of pressure pipe
Remove clogging, and check oil for
contamination/replace oil.
Outlet shut-off valve of oil
separator is closed.
Operator forgot to restore after
shut down operation.
Human error
Open the valve or perform emergent
stop.
Be sure to conduct tagout while
handling valves.
Be sure to check valves before
starting the compressor.
07: Discharge temperature is abnormally high.
Direct cause
Root cause
Action
Overheated during
operation
Insufficient refrigerant flow
See the causes listed in item 02
above.
Heat load on load side is
higher than design value.
Inspect the conditions on load side
(warehousing volume,
opening/closing of doors, etc.), and
take necessary measures.
Failure of low pressure
protection device, pressure
sensor, relay, etc.
Identify defective devices, investigate
causes of failure and take necessary
actions.
Then, replace failed device(s).
Non-condensable gases
mixed into the system
Leak on low pressure side
Perform a leak check, and take
necessary measures.
Air-purge the heat exchanger.
Oil supply temperature is
high.
Heat exchange failure in oil
cooler
For water-cooling system, see "Heat
exchange failure in heat exchanger" in
06 above.
For liquid cooling system, check liquid
supply expansion valve, temperature
sensor and related
relays/wiring/terminals, and take
necessary actions.
Oil temperature rise protection
feature does not function.
Check temperature protection device,
temperature sensor and related
relays/wiring/terminals, and take
necessary actions.
Defective discharge
temperature
detection/protection
feature.
Failure of temperature
protection device, temperature
sensor, relay, etc.
Identify defective devices, investigate
causes of failure and take necessary
actions.
Then, replace failed device(s).
Insufficient oil supply
See "Low oil pressure" in Item
04 above.
Same as left
