2205Q2JE-HO-S6-N_2020.01. 
Chapter 6 Troubleshooting 
SCV-series Screw Compressors 
6-6 
  Trouble  Direct causes  Factors  Actions 
 
mechanical 
seal 
period (no oil film 
on sliding surfaces) 
 
specific conditions, 
such as heat load 
being intermittent. 
If stoppage period becomes more 
than one week, manually operate oil 
pump as well as manually turn 
compressor rotor shaft, or equip 
external seal portion with oil pot. 
 
 
For aging degradation, replace 
O-ring. 
For other specific causes, the same 
factors and actions described above 
of “Damaged sliding surface due to 
excessive heat of sliding surface” 
*  Occurs in 
excessive 
refrigerant 
For liquid backflow operation, 
remove the causes. 
For malfunction of oil heater and 
other devices on control circuit, 
ring or mating ring 
For aging degradation, replace 
parts. 
For other specific causes, the same 
factors and actions described above 
of “Damaged sliding surfaces due to 
excessive heat of sliding surface” 
between operating 
conditions (working 
temperature 
ranges, refrigerant, 
etc.) and lubricant 
cant or change in 
operating 
conditions since 
installation of 
compressor. 
Re-examine operating conditions if 
possible. 
If not, refer to Chapter 4.1, 
“Lubricant (Refrigerant Oil)”, and 
re-select lubricant and replace all 
amount of current lubricant with new 
contact conditions 
of sliding surfaces 
attached to sliding 
surfaces due to 
contamination of 
 
Equip oil supply line with bypass 
filter. 
ment 
Overhaul compressor to replace 
parts, and reassemble it. 
Check using assembly check sheet. 
sound from 
mechanical 
seal part 
after replacement 
until sliding surface 
fits each other, 
squeaking sound 
caused by contact 
of sliding surfaces 
high in hardness as 
well as in density, 
so it takes a while 
for them to fit each 
other. 
Squeaking itself does not cause 
seal leak or functional deterioration 
of seal. 
Squeaking normally subsides after 
few dozens of hours, but it could 
continue in rare cases. 
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In this case, contact our service