Mitsubishi 3000GT Service Manual page 1248

REFRIGERANT LEAK REPAIR
PROCEDURE
LOST CHARGE
If the system has lost all charge due to a leak:
(1) Evacuate the system. (See procedure.)
(2) Charge the system with approximately one
pound of refrigerant.
(3) Check for leaks.
(4) Discharge the system.
(5) Repair leaks.
(6) Replace receiver drier.
Caution
Replacement filter-drier units must be
sealed while in storage. The drier used in
these absorb water/water vapor
units will
quickly upon exposure to the atmosphere.
When installing a drier, have all tools and
supplies ready for quick reassembly to
avoid keeping the system open any longer
than necessary.
(7) Evacuate and charge the system.
LOW CHARGE
If the system has not lost all of its refrigerant charge,
locate and repair all leaks. If it is necessary to in-
crease the system pressure to find the leak (be-
cause of an especially low charge) add refrigerant.
If it is possible to repair the leak without discharging
the refrigerant system, use the procedure for cor-
recting low refrigerant level.
HANDLING TUBING AND FITTINGS
Kinks in the refrigerant tubing or sharp bends in
the refrigerant hose lines will greatly reduce the
capacity of the entire system. High pressures are
produced in the system when it is operating. Ex-
treme care must be exercised to make sure that
all connections are pressure tight. Dirt and moisture
can enter the system when it is opened for repair
or replacement of lines or components. The follow-
ing precautions must be observed.
The system must be completely discharged before
opening any fitting of connection in the refrigeration
system. Open fittings with caution even after the
system has been discharged. If any pressure is
noticed as a fitting is loosened, allow trapped pres-
sure to bleed off very slowly.
Never attempt to rebend formed lines to fit. Use
the correct line for the installation you are servicing.
A good rule for the flexible hose lines is keep the
radius of all bends at least 10 times the diameter
of the hose.
Sharper bends will reduce the flow of refrigerant.
The flexible hose lines should be routed so that
they are at least 80 mm (3 in.) from the exhaust
manifold.
HEATERS AND MANUAL
AIR CONDITIONING
TSB Revision
It is good practice to inspect all flexible hose lines
at least once a year to make sure they are in good
condition and properly routed.
O-ring used on connections are not reusable.
COMPRESSOR NOISE
When investigating an air conditioning related noise,
you must first know the conditions when the noise
occurs. These conditions are: weather, vehicle
speed, gear in neutral, engine temperature or any
other special conditions.
Noises that develop during air conditioning opera-
tion can often be misleading. For example: what
sounds like a failed front bearing or connecting
rod, may be caused by loose bolts, nuts, mounting
brackets, or a loose clutch assembly. Verify acces-
sory drive belt tension (power steering or generator).
Improper accessory drive belt tension can cause
a misleading noise when the compressor is en-
gaged and little or no noise when the compressor
is disengaged.
Drive belts are speed sensitive. That is, at different
engine speeds, and depending upon belt tension,
belts can develop unusual noises that are often
mistaken for mechanical problems within the com-
pressor.