Pontiac FIREBIRD 1972 Service Manual page 114

CUSTOM AIR CONDITIONING 1A-55
c. With compressor operating, slowly open valve on
refrigerant drum and allow refrigerant to flow
into system (through manifold guage set) until
liquid indicator clears up and immediately shut
off valve at gauge set or on refrigerant drum.
Check weight of refrigerant drum and pail of wa-
ter. Then slowly open valve on gauge set (or re-
frigerant drum) and add one-half pound of
refrigerant. Note total amount of refrigerant ad-
ded.
DISPOSABLE CAN METHOD:
Make sure the outlet valve on the J 6271 valve is
fully clockwise and attach the J 6271 to a 15 oz.
can of refrigerant by backing off the valve from
the top of the retainer, slipping the valve onto the
can and turning the valve into the retainer until
tight. DO NOT accidentally open outlet valve
during this operation as turning the valve into the
retainer punctures the top of the can to make it
ready for charging.
Connect center flexible line of gauge set to the
fitting on the valve.
Start engine, move temperature control lever to
full cold position, set blower switch to high speed
and system to A/C mode. Operate engine for ten
minutes at 2000 rpm to stabilize system.
With compressor operating, slowly open valve on
refrigerant can and allow refrigerant to flow into
system (through manifold gauge set) until liquid
indicator clears up and immediately shut off valve
at guage set and on refrigerant can. Check weight
of can and valve assembly and record.
Add an additional one-half pound of refrigerant
by adding refrigerant from the can just weighed
until can weighs one-half pound less. If can is
empty before one-half pound is added to system,
attach another can and add refrigerant until the
entire one-half pound has been added.
Close valves at refrigerant drum or can.
Test for leaks and make pressure check of system as
outlined under OPERATIONAL TEST.
Disconnect thermal limiter jumper and connect li-
miter.
CHECKING COMPRESSOR OIL LEVEL
AND ADDING OIL
The refrigeration system with the six-cylinder axial com-
pressor requires 11 fluid ozs. of 525. viscosity oil. After the
system has been operated, oil circulates throughout the
system with the refrigerant. Hence, while the system is
running, oil is leaving the compressor with the high pres-
sure gas and is returning to the compressor with the suc-
tion gas.
To enhance return of oil to the compressor under partially
depleted refrigerant charge conditions, an oil bleed line
from the evaporator to the suction line at the P.O.A. valve
has been provided. The core in the bleed line fitting at the
P.O.A. valve has a special low force spring in it which
allows the core to open a 5 to 12 psi pressure difference.
It is important that this core not be replaced with a stand-
ard tire core.
The oil level in the compressor should not be checked as
a matter of course, such as is done in the car engine
crankcase. In general, the compressor oil level should be
questioned only in cases where there is evidence of a major
loss of system oil such as:
a. Broken hose or severe hose fitting leak.
b. Oil sprayed in large amounts under the hood due to
a badly leaking compressor seal.
c. Collision damage to refrigeration system compo-
nents.
REPLACING REFRIGERATION SYSTEM
COMPONENTS OTHER THAN COMPRESSOR
If there are no signs of excessive oil leakage, add the
following amount of oil depending on component re-
placed:
1. Evaporator
-
3 fluid ozs.
2. Condenser
-
1 fluid oz.
3. Receiver
-
1 fluid oz.
4. No oil for P.O.A. valve, expansion valve or hoses.
When refrigerant system components other than the com-
pressor are replaced and there are signs of abundant oil
leakage, the compressor must also be removed and oil
drained from the compressor. The amount of oil to put
back into the compressor is found as follows:
DO NOT add any more oil than is necessary or maximum
cooling will be reduced.
Remove the compressor and place in a horizontal
position with the compressor drain plug downward,
drain oil from compressor into an empty graduated
bottle, measure the amount of oil and discard this oil.
If the quantity of oil measured is more than 4 fluid
ozs., replace into the compressor the same amount of
clean oil as the oil drained, plus the following amount
for the refrigeration system component being
changed: