05: Intermediate Pressure Is Unusually High - mycom 4032**C Series Instruction Manual

04: Low oil pressure (continued)
Direct cause
Insufficient oil in oil
separator.
Oil pressure detection
function is defective.

05: Intermediate pressure is unusually high.

Direct cause
High suction pressure
Liquid flow-back from
intermediate liquid cooler.
There is problem in
compressor's high-stage.
Compound 2-stage Screw Compressor 4032**C
Root cause
Extensive oil leak
Failure of oil pressure
protection device, pressure
sensor, relay, etc.
Pressure pipe is clogged.
Root cause
Heat load on load side is
higher than design value.
Malfunction of suction pressure
control mechanism
Malfunction of compressor's
capacity control
Failure or internal leakage of
intermediate liquid supply
expansion valve
Malfunction of capacity control
on compressor's high- stage
Excessive wear or sliding part
damage of the part(s) on
compressor's high- stage
6-3
2201Q4JE-MY-C9-N_2018.01.
Chapter 6 Troubleshooting
Action
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).
Identify defective devices, investigate
causes of failure and take necessary
actions.
Then, replace failed device(s).
Remove clogging, and check oil for
contamination/replace oil.
Action
Inspect the conditions on load side
(warehousing volume,
opening/closing of doors, etc.), and
take necessary measures.
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.
See Item No. 11 "Capacity control
malfunction".
Repair or replace.
See Item No. 11 "Capacity control
malfunction".
Overhaul compressor and replace
parts.
Replace the whole quantity of
lubricating oil.