COllector
can
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24-36 AIR-CONDITIONING-Service Adjustment Procedures
D&ARG,NG THE SYSTEM
Since the air conditioning refrigerant system is pressurized, it will
be necessary to completely discharge the system (in a well ven-
tilated area) before replacing any refrigerant component. The pro-
cedure is as follows:
(1) Install manifold gauge set. Make sure the gauge set valves are
closed before attaching the hoses to the refrigerant system.
(2) Install a long hose to the manifold gauge set connector. Run
this hose to the oil collector can near a shop exhaust system.
A good oil collector can may be made from a large empty
coffee can with a plastic top. Slit the plastic top in the form of
a Y to make an entrance for the refrigerant hose and an exit for
the gas.
(3) Open the compressor discharge and suction line pressure
valves and blow the refrigerant into the oil collect can. Watch
to make sure the hose does not blow out of the collector can.
(4) When the system has been completely discharged, measure
the amount of oil collected in the can. The amount of oil mea-
sured should be added to the refrigerant system before it is
re-charged. Add new oil-discard the used oil.
Caution
It is important to have the correct amount of oil in the refrig-
erant system.
Too little oil will provide inadequate compressor lubrication and
cause a compressor failure. Too much oil will increase discharge
air temperature.
When a 6P148 compressor is installed at the factory, it
contains 110 c.c. (3.7 U.S.fl.oz., 3.9 Imp.fl.oz.) of refrigerant oil.
While the air conditioning system is in operation, the oil is
carried through the entire system by the refrigerant. Some of
this oil will be trapped and retained in various parts of the
system.
When the following system components are changed, it is nec-
essary to add oil to the system to replace the oil being removed
with the component.
Compressor - 4Occ (1.4 U.S.fl.oz., 1.4 Imp.fl.oz.)
Condenser - 30 cc (1.0 U.S.fl.oz., 1.1 Imp.fl.oz.)
Evaporator - 60 cc (2.0 U.S.fl.oz., 2.1 Imp.fl.oz.)
Piping - 10 cc (.3 U.S.fl.oz., .4 Imp.fl.oz.)
Receiver drier - 0 cc (0 U.S.fl.oz., 0 Imp.fl.oz.)
EVACUATING THE SYSTEM
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Whenever the system has been opened to the atmosphere, it is
absolutely essential that the system be evacuated or “vacuumed”
to remove all the air and moisture. Air in the refrigerant system
causes high compressor discharge pressures, a loss in system
performance, and oxidation of the compressor oil into gum and
varnish. Moisture in the refrigerant system can cause the expan-
sion valve to malfunction. Under certain conditions, water can
react with the refrigerant to form destructive acids. It is necessary
to adhere to the following procedure to keep air and moisture out
of the system.
(1) Install manifold gauge set. Make sure the gauge set valves are
closed before attaching the hoses to the refrigerant system.
(2) Discharge the system if the manifold gauge set indicates pres-
sure in the system.
(3) Connect a long test hoses from gauge set manifold center
connection to vacuum pump.
(4) Open both manifold gauge set valves.
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AIR-CONDITIONING -Service Adjustment Procedures 24-41
COMPRESSOR NOISE NWLM
When investigating an air conditioning related noise, you must first know the conditions when the noise occurs.
These conditions are: weather, vehicle speed, in gear or neutral, engine temperature or any other special
conditions.
Noises that develop during air- conditioning operation 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 accessory drive belt tension (power
steering, alternator or air pump). Improper accessory drive belt
tension can cause a misleading noise when the compressor is engaged 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 compressor.
Adjustment Procedures
(1) Select a quiet area for testing. Duplicate conditions as much as possible. Switch compressor on and off several
times to clearly identify compressor noise.
To duplicate high ambient conditions (high head pressure), restrict air-flow through
condenser. Install
manifold gauge set to make sure discharge pressure does not exceed 2,070 kPa (300 psi).
(2) Tighten all compressor mounting bolts, clutch mounting bolt, and compressor drive belt. Check to assure clutch
coil is tight (no rotation or wobble).
(3) Check refrigerant hoses for rubbing or interference that can cause unusual noises.
(4) Check refrigerant charge (See “Charging the System”).
(5) Recheck compressor noise as in Step 1.
(6) If noise still exists, loosen compressor mounting bolts and retorque. Repeat Step 1.
(7) If noise continues, replace compressor and repeat Step 1.
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