mycom SCV Series Instruction Manual page 124

Trouble
09 Faulty Imprecision in
indication of compressor
capacity indicator
control posi-
Imprecision in
tion
controller capacity
control indicator
10 Capacity Refer to each factor
control in "Imprecision in
malfunction controller capacity
control indicator"
above.
Undetected 100 %
or 0 % by indicator
Malfunction of
unloader solenoid
valves or related
relays, etc. for
capacity control
Internal leakage of
unloader solenoid
valves for capacity
control
SCV-series Screw Compressors
Direct causes
Loose screws for
indicator
Worn groove of
compressor
indicator cam
Worn guide pin
(dowel pin) of com-
pressor push rod
Malfunction in
potentiometer
Maladjustment of
zero point and span
adjustment for E/E
positioner
Malfunction of E/E
positioner or its
indicator
Loose terminals or
faulty wiring
Same as on the left
Malfunction of
micro-switch
Most cases are due
to coil burnout.
Expanded oil and
refrigerant liquid
trapped inside
unloader cylinder
due to temperature
increases.
Factors
Manually tighten screws to the 0 %
indication position of compressor
capacity control.
Most cases are due to prolonged
partial load operation. In this case,
replace indicator cam.
* Indicator cam that is currently
manufactured has reinforced
groove.
Guide pin of compressor push rod is
currently reinforced as well.
However, if only indicator cam has
reinforced groove, wear of guide pin
might occur. Replace dowel pin.
If cased by aging degradation or
prolonged partial load operation,
replace potentiometer.
If cased by excessive vibration of
compressor, take vibration
reduction measures, and then
replace parts.
Readjust it.
For aging degradation, replace E/E
positioner.
For unique causes such as surge
current, remove the causes or take
measures.
For loose terminals, tighten them.
For faulty wiring, replace it.
Same as on the left
Replace micro-switch.
For aging degradation, replace
parts.
For water leakage, etc., remove the
cause and replace parts.
Refer to the solenoid valve
instruction manual for details.
If caused by prolonged low load
operation, improve by re-examining
the operation method.
Install a capacity control hydraulic
line with an in-line check valve
(internal reversal-stoppage valve)
and an oil bypass line.
6-7
2205Q2JE-HO-S6-N_2020.01.
Chapter 6 Troubleshooting
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