mycom 2016 C Series Instruction Manual page 113

Symptom
02 Compressor Low pressure
stops protection circuit
immediately activates.
after
startup.
Motor overload
03 Unusually Refer to direct
low cause, "Low
pressure pressure protection
(decrease of circuit activates", in
suction Item 02 above.
pressure)
04 Low oil Oil filter element is
pressure clogged.
(low * Pressure
lubrication difference
oil supply between the
pressure) outlet port and
inlet port is large.
Insufficient oil in oil
separator.
Compound 2-stage Screw Compressor 2016**C
Direct cause
Insufficient
refrigerant flow
 Insufficient
refrigerant
 Insufficient liquid
supply
 Heat exchange
failure in heat
exchanger
Failure of low
pressure protection
device, pressure
sensor, relay, etc.
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.
Same as left
Contamination of
lubricant
Internal defects of
compressor
Oil heater is not
functioning,
refrigerant
dissolves
excessively when
the machine is
stopped, and oil
loss occurs at
startup.
Insufficient oil
return due to
insufficient
refrigerant
circulation
Troubles such as
clogging in oil
return passage
Root cause
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.
Identify defective devices,
investigate causes of failure and
take necessary actions.
Then, replace failed device(s).
Same as left
Remove clogging, and check oil for
contamination/replace oil.
Check for oil contamination and
conduct vibration/noise diagnosis.
Overhaul compressor if necessary.
Inspect oil heater alone, inspect
relays, etc. on related circuits, and
replace parts as necessary.
Correct insufficient refrigerant
circulation, and return oil from
load-side heat exchanger.
* Supply lubricant temporarily.
Remove causes of the trouble, and
restore the system.
6-2
2200LZJE-HO-C6-N_2013.12.
Chapter 6 Troubleshooting
Action