GMC 4000 Series Service Manual page 96

com pressor. The amount of oil to put back into the
com pressor is found as follows: DO NOT add any
more oil than is necessary or maximum cooling
will be reduced.
1. Remove the com pressor and place in a hor­
izontal position with the com pressor drain plug
downward, drain com pressor in an empty grad­
uated bottle, measure the amount of oil and discard
this oil.
2. If the quantity of oil measured is more than
4 fluid ozs., replace into the com pressor the same
amount of clean oil as the oil drained, plus the
following amount for the refrigeration system com­
ponent being changed.
a. Evaporator - 3 fluid ozs.
b. Condenser - 1 fluid oz.
c. Receiver-dehydrator assembly - 1 fluid oz.
Neglect any fluid oil coating lo ss in case of
line change.
3. If the oil quantity drained from the com­
pressor is le ss than 4 ozs., replace into the com­
pressor 6 fluid ozs. of clean oil, plus the amount
shown previously for the respective component
replacements.
4. Replace com pressor and system compon­
ents.
5. Evacuate, charge and perform operational
test.
CHECKING FOR LEAKS
Leak detector J-6084 as used for checking for
leaks in system, is a gas-operated torch-type leak
detector using a replaceable cylinder.
ASSEMBLING AND LIGHTING THE UNIT
1. Remove dust cap from cylinder.
2. Close valve knob on detector unit.
3. Thread detector unit onto top of fuel cylin­
der. Tighten finger tight.
4. Attach search hose assembly to detector
unit (fig. 13).
5. Open control valve until slight hiss of gas
is heard, then light gas at opening in chimney.
CAUTION: Do not use lighted de­
tector in any place where combustible
or explosive gases, dusts or vapors
may be present.
6. Adjust the flame until the desired volume
is obtained. A pale blue flame approximately 3 /8 "
above the reaction plate is best for detecting leaks.
NOTE: The reaction plate will be heated to a
cherry red.
CORRECTION FOR YELLOW FLAME
If the flame is yellow, insufficient air is being
G M C S E R V I C E M A N U A L
inspirated or the reaction plate is dirty. Insuffic­
ient air may be caused by:
tube.
through the detector will usually clear dirt or
foreign matter. If a yellow flame is caused by
dirty reaction plate, allow the flame to burn for
several minutes. This will usually burn the plate
clean. If an oxide film appears on the reaction
plate from continued use, it will reduce the sen si­
tivity of the detector. This may be remedied by
removing the plate and scraping the surface gently
with a knife.
TO CLEAN ORIFICE
anything through the hole.
tube. This will expose orifice block which is in­
serted into the end of the tube.
burner tube; thread burner head onto burner tube
AIR CONDITIONING
Figure 13— Checking for Refrigerant Leak
1. Obstructed or partially collapsed suction
2. Dirt or foreign substance in burner tube.
3. Dirty or partially clogged orifice.
Blowing air through the suction tube and back
1. Never attempt to clean orifice by passing
2. Unthread burner head assembly from burner
3. Remove orifice block from tube.
4. Reverse orifice block and replace against
Sec. 1
Page 89