Toshiba Super MMU-AP0091H Service Manual page 247

15-3. Check Procedure to Search the Cause of Compressor Oil
Shortage
Are balance pipes of all the outdoor units
in the same refrigerant circuit opened fully?
Is there no coming-off, miscabling,
or incorrect installation on sensors of the unit
of which compressor has been replaced?
Is TK1, TK2, TK3 or TK4 sensor
characteristics of the unit of which compressor
has been replaced correct?
Check oil-equalization circuit in the following procedure
under condition that the compressor is removed.
Check items and procedure for the oil-equalization circuit under condition that the compres-
sor is removed
Check items
Outdoor PMV leakage
Check valve leakage of main
discharge pipe
Check of refrigerant
stagnation cause in
Check valve leakage of
compressor
discharge pipe
Check valve leakage of oil-
equalization circuit
SV3A valve leakage
SV3B valve clogging
Check of oil
SV3E valve clogging.
shortage cause in
Clogging of oil-return
compressor
capillary
SV3D valve capillary
clogging.
Clogging of oil-return
capillary
YES
YES
YES
Position
A 1) Press nitrogen gas in from check joint of liquid pipe, and check pressure at check joint
B of discharge pipe.
If pressure of check joint of discharge pipe becomes high, leakages from outdoor PMV
and check valve of main discharge pipe are considered. Exchange the parts.
2) If the pressure up is not found, open outdoor PMV fully and recheck pressure.
If pressure of check joint of discharge pipe becomes high, leakage from check valve of
main discharge pie is considered. Exchange the parts.
C 3) When gas leaks from welded part of oil-equalization pipe where compressor has been
removed under condition that nitrogen gas is pressed in from check joint of main
discharge pipe, leakage from check valve of main discharge pipe is considered.
Exchange the parts.
D 4) When gas leaks from welded part of oil-equalization pipe where compressor has been
removed under condition that nitrogen gas is pressed in from check joint of discharge
pipe, leakage from check valve of oil-equalization circuit is considered.
Exchange the parts.
E 5) Open SV3B valve manually under condition that nitrogen gas is pressed in from check
F joint of discharge pipe. When gas leaks from welded part of suction pipe where
compressor has been removed, SV3A valve leakage is considered. Exchange the parts.
Next, open SV3A valve and SV3B valve manually. If gas leaks from welded part of
suction pipe where compressor has been removed, SV3A valve leakage is considered.
Exchange the parts.
G 6) Open SV3E valve manually under condition that nitrogen gas is pressed in from check
H joint of discharge pipe. When gas does not output from welded part of suction pipe
where compressor has been removed, there is clogging at SV3E valve or oil-return
capillary. Exchange the parts.
I 7) Open SV3D valve manually under condition that nitrogen gas is pressed in from check
H joint of discharge pipe. When gas does not output from welded part of suction pipe
where compressor has been removed, there is clogging at SV3D valve or oil-return
capillary. Exchange the parts.
NO
Open valve of the balance pipe fully.
Correct miscabling or incorrect
installation at sensor installation:
NO
TK1: CN514/TK2: CN515
TK3: CN516/TK4: CN523
NO
Sensor error
Procedure
247
Exchange