2201Q4JE-MY-C9-N_2018.01.
Chapter 6 Troubleshooting
Compound 2-stage Screw Compressor 4032**C
6-3
04: Low oil pressure (continued)
Direct cause
Root cause
Action
Insufficient oil in oil
separator.
Extensive oil leak
Inspect machine room and around the
compressor, and take necessary
actions.
Check if there is oil floating in cooling
water system.
→If there is, check for oil leak from
heat transmission tube of oil cooler
and take necessary actions.
If piping is damaged due to excessive
vibration, take measures to reduce
vibration (including measures for
resonance vibration).
Oil pressure detection
function is defective.
Failure of oil pressure
protection device, pressure
sensor, relay, etc.
Identify defective devices, investigate
causes of failure and take necessary
actions.
Then, replace failed device(s).
Pressure pipe is clogged.
Remove clogging, and check oil for
contamination/replace oil.
05: Intermediate pressure is unusually high.
Direct cause
Root cause
Action
High suction pressure
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.
Malfunction of suction pressure
control mechanism
In case of pressure sensing failure,
replace the pressure sensor.
* In some cases, pressure pick-up
position is improper. → Change the
position.
If there is a problem in device(s) on
the control circuit, find the defective
device(s) and replace it.
If parameter (set value) on the control
circuit is improper, optimize it.
In case of malfunction of pressure
control valve, replace the valve or
remove the cause.
Malfunction of compressor's
capacity control
See Item No. 11 "Capacity control
malfunction".
Liquid flow-back from
intermediate liquid cooler.
Failure or internal leakage of
intermediate liquid supply
expansion valve
Repair or replace.
There is problem in
compressor's high-stage.
Malfunction of capacity control
on compressor's high- stage
See Item No. 11 "Capacity control
malfunction".
Excessive wear or sliding part
damage of the part(s) on
compressor's high- stage
Overhaul compressor and replace
parts.
Replace the whole quantity of
lubricating oil.
