mycom i160S - Page 103

2203M4JE-MY-iS2-N_2017.04.
Chapter 6 Troubleshooting
Screw Compressor i-series
6-5
Symptom
Direct cause
Root cause
Action
06
Discharge
temperature
is abnormally
high.
Defective discharge
temperature
detection/protection
feature.
Failure of
temperature
protection switch,
pressure sensor,
relay, etc.
Identify defective device(s),
investigate causes of failure and
take necessary actions.
Then, replace failed device(s).
Insufficient oil
supply
See "Low oil
pressure" in Item
04 above.
Same as left
07
Leak from
mechanical
seal
Initial leak after
replacement until
sliding surfaces
settle
In some cases,
immediately after
replacement, the
compressor-
specific operating
conditions and the
pressure receiving
conditions of
machined sliding
surface is unstable.
In case of initial leak, although
leak amount might increase
temporarily, it will decrease
gradually. Check that leak does
not increase continuously.
Duration of initial leak depends on
design/operating conditions. It is
approximately 200 hours, as a
rough indication.
Sliding surface is
roughened due to
overheating.
Started and
stopped too many
times.
* In case of
standard
equipment, "four
or more times per
hour" is
considered "too
many".
If heat load is less than the level
set by the equipment's design
conditions, review the operating
conditions and set control such
that equipment is started/stopped
less frequently.
In case of capacity control
malfunction, see "Capacity control
malfunction" in item 09.
The amount of
lubricating oil
contained in
refrigerant gets
smaller, resulting in
decreased
viscosity.
In case of liquid flow-back,
remove the cause(s).
If oil heater or devices on its
control circuit are defective,
replace the defective part.
Overheated
operation
See the causes in item 02,
"Insufficient refrigerant flow".
Oil supply
temperature is
high.
See the causes in item 06, "Oil
supply temperature is high".
Machine is stopped
for a long time.
(No oil film on
sliding surfaces)
User-specific
conditions, such as
intermittent heat
load
If machine is sometimes stopped
longer than a week, take either of
the following measures:
(i) Conduct the compressor shaft
turning by removing the motor
spacer plate (P/N: 235-2) once
per month.
(ii) Attach an oil pot to other than
sealed areas
Deteriorated part(s)
Hardened O-ring
If deteriorated over time, replace.
For other specific causes, see the
causes/action for symptom
"Overheating of sliding surface".