2205Q2JE-HO-S6-N_2020.01.
Chapter 6 Troubleshooting
SCV-series Screw Compressors
6-2
Trouble Direct causes Factors Actions
stops imme-
diately after
startup.
protection circuit
activated
ant circulation
volume
If any heat exchange failures as
typified by poor defrost
performance, investigate the cause
For malfunction in pressure
regulating valve operation, replace
pressure regulating valve, or
pressure protection
device, pressure
sensor, relays, etc.
Identify malfunctioning devices,
examine their causes, and take
measures.
Then, replace malfunctioning
In many cases, motor overload that occurs just after startup is
caused by the motor, not by the refrigeration cycle. Refer to
the motor instruction manual.
low
pressure
(low suction
causes “Low
pressure protection
circuit activated” in
oil-supply
pressure
element
* Big difference in
outlet/inlet
pressures
lubricant
Remove clogging. Check oil
contamination level and change
compressor
Check oil contamination level. After
vibration noise diagnosis, overhaul
amount in oil
separator
heater, excessive
refrigerant dissolu-
tion during
stoppage, thus
resulting in oil carry
Inspect relays, etc., on related
circuits.
And replace parts as needed.
return caused by
insufficient
refrigerant
Resolve insufficient volume of
refrigerant circulation, and then
return oil from load side heat
exchanger.
* Charge lubricant temporarily.
clogging in oil
Remove any causes of trouble to
restore.
Inspect machine room and around
compressor and take measures.
Inspect for presence of oil floating in
cooling water system.
If there is any oil floating, check for
oil leak in oil cooler heat exchanger
For damage in pipes, etc., caused
by excessive vibration, take
vibration reduction measures
(including sympathetic vibration