2200LZJE-HO-C6-N_2013.12.
Chapter 6 Troubleshooting
Compound 2-stage Screw Compressor 2016**C
6-2
Symptom
Direct cause
Root cause
Action
02 Compressor
stops
immediately
after
startup.
Low pressure
protection circuit
activates.
Insufficient
refrigerant flow
Insufficient
refrigerant
Insufficient
liquid
supply
Heat exchange
failure in heat
exchanger
To correct insufficient liquid supply,
inspect expansion valve and liquid
supply strainer. Take necessary
actions.
In addition, inspect devices and
parameters (set values) of the
expansion valve aperture adjusting
mechanism, and take necessary
actions.
If there are any problem
(insufficiency) in heat exchange,
such as malfunction of defrosting,
investigate the cause and take
necessary actions.
In case of malfunction of pressure
adjustment valve, replace the valve
or remove the cause.
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).
Motor overload
Motor overload that occurs just after startup is mostly
caused not by the refrigeration cycle but by the motor.
Refer to the instruction manual of the motor.
03 Unusually
low
pressure
(decrease of
suction
pressure)
Refer to direct
cause, "Low
pressure protection
circuit activates", in
Item 02 above.
Same as left
Same as left
04
Low oil
pressure
(low
lubrication
oil supply
pressure)
Oil filter element is
clogged.
* Pressure
difference
between the
outlet port and
inlet port is large.
Contamination of
lubricant
Remove clogging, and check oil for
contamination/replace oil.
Internal defects of
compressor
Check for oil contamination and
conduct vibration/noise diagnosis.
Overhaul compressor if necessary.
Insufficient oil in oil
separator.
Oil heater is not
functioning,
refrigerant
dissolves
excessively when
the machine is
stopped, and oil
loss occurs at
startup.
Inspect oil heater alone, inspect
relays, etc. on related circuits, and
replace parts as necessary.
Insufficient oil
return due to
insufficient
refrigerant
circulation
Correct insufficient refrigerant
circulation, and return oil from
load-side heat exchanger.
* Supply lubricant temporarily.
Troubles such as
clogging in oil
return passage
Remove causes of the trouble, and
restore the system.