GMC 4000 Series Service Manual page 93

Sec. 1
Page 86
AIR CONDITIONING
though the proper amount of refrigerant is in the
system . Air inlet temperature must be 70°F., or
above to make an accurate check. In no case should
the system be charged with more than 3-1/4 lbs.
of refrigerant.
8. When refrigerant has been injected, con­
tinue to operate system and test for proper oper­
ation as outlined under "Performance Testing."
9. When satisfied that air conditioning system
is operating properly, stop engine, remove gauge
set and replace protective caps on com pressor
fittings.
CAUTION: A considerable amount
of refrigerant will collect in the high
pressure line, since some of this re­
frigerant will have condensed into liquid
refrigerant. Wrap the high pressure
gauge fitting at the com pressor with a
shop cloth before disconnecting the
Schrader valve from the gauge fitting,
to prevent injury to personnel.
10. Using leak detector J-6084, check com­
plete system for leaks, as explained later under
"Checking For Leaks."
REFRIGERANT-12 DISPOSABLE CAN METHOD
After having depressurized, repaired (if n eces­
sary), and evacuating the refrigerant system , the
system may be charged as follows when using Re­
frigerant-12 disposable cans:
1. Obtain five "one"pound cans of Refrigerant-
.
12
2. Mount four cans in J-6272-01 No. 4 Multi­
opener or attach J-6271 Fits-A ll valve (single can
opener valve) on one can.
CAUTION: Make sure outlet valve
on opener is closed (clockwise) before
installing opener.
a. If the J-6272-01 No. 4 Multi-opener is used,
raise locking lever, position four cans of refrig­
erant and force the locking lever down to secure
cans and at the same time puncture the top of the
can to make it ready for charging.
b. If the J-6271 Fits-A ll valve is used, back
off the valve from the can top retainer, slip the
valve on to the can and turn the valve into the re­
tainer until tight. DO NOT 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.
3. Connect center flexible line of gauge set to
the fitting on a can opener valve.
NOTE: If line at center gauge fitting has not
been purged of air, loosen line at center fitting on
G M C S E R V I C E M A N U A L
gauge set and "crack" valve at can opener (for a
second or two) to force air from theline. Retighten
line at center fitting.
single can) and also low pressure and high p res­
sure valves on manifold gauge set. Leave can valve
open until all refrigerant has entered the refrig­
eration system . Close valve on can.
and the J-6271 valve, disconnect valve from can,
leaving valve closed to flexible line to the center
fitting of the manifold gauge set. Install valve on a
new and full disposable can of Refrigerant-12, and
repeat until three and one quarter "one-pound"
cans of refrigerant have been used to charge the
system . The system requires 3 -1 /4 pounds of re­
frigerant to have a proper charge. (Actually the
net weight of refrigerant is 15 ozs. per can, there­
fore it will be necessary to use 3 -1 /2 to 4 cans. In
no case should the system be charged with more
than 3 -1/4 pounds of refrigerant.)
available, complete charging as explained in 4a
previously.
control knob at full cold position and blower con­
trol for high speed with "AIR" knob in "OUTSIDE"
position.
denser is below 70°F., when this check is made,
bubbles may appear even though the proper amount
of refrigerant is in the system . Air inlet temper­
ature must be 70°F., or above to make an accurate
check. In no case should the system be charged
with more than 3 -1 /4 pounds of refrigerant.
tinue to operate system and test for proper oper­
ation as outlined previously under "Performance
Testing."
is operating properly, stop engine, remove gauge
set and replace protective caps on suction and d is­
charge fittings.
system for leaks as explained later under "Check­
ing For Leaks."
4. Open valve on No. 4 Multi-opener (or on
a. If the system is charged using single cans
If the J-6271 Fits-A ll valve for single cans is
5. Close valves on manifold gauge set.
6. Operate engine at 2000 rpm with "TEMP"
NOTE: If air inlet temperature at the con­
7. When refrigerant has been installed, con­
8. When satisfied that air conditioning system
CAUTION: A considerable amount
of refrigerant will collect in the high
pressure line, since some of this re­
frigerant will have condensed into liquid
refrigerant. Wrap the high pressure
fitting at the com pressor with a shop
cloth before disconnecting the Schrader
valve from the gauge fitting to prevent
damage or injury to personnel.
9. Using leak detector J-6084, check complete