Chevrolet 70 1969 Series, Shop Manual

Page: 91 / 913

CAB A N D
BO DY M O U N T IN G S
1-64
O-RING
SEAL
« « g 8 "
DRIVE BAIL
SUCTIO N
SHAFT PULLEY
REED SEAL
BEARING
REAR HEAD
. . . . ARMATURE
'
I
0 |L MAINSHAFT \
MAINSHAFT \ \ \ PLATE
DISCHARGE SUCTIO N
piCK-UP REAR SWASH FRONT FRONT CLUTCH V AND HUB
VALVE Pi ATE REED TUBE
BEARING PLATE BEARING HEAD COIL PULLEY ASSEMBLY
T - 3 1 I 9
Figure 9— Refrigerant Compressor
The opposing forces, spring pressure and at­
mospheric pressure on the one side of the valve
diaphragm and evaporator pressure on the opposite
side of the diaphragm constitute a balanced valve
and control its operation.
When the evaporator pressure rises above the
manual spring setting, this increase in evaporator
pressure is exerted against the valve piston and
through the bleed holes in the piston to the under­
side of the diaphragm. The pressures under the
diaphragm overcome the spring pressure causing
the valve piston to move in an opening direction.
As the piston opens^ it reaches a balanced position
and the evaporator pressure returns to its original
setting (23-24 p.s.i.g.).
When the evaporator pr essure drops below the
predetermined setting, the spring pressure over­
comes the opposing evaporator pressure and forces
the piston in a closing direction until the predeter­
mined pressure setting is maintained (23-24p.s.i.g.)
The minimum operating pressure of the suction
throttling valve is pre-set by an adjustment screw.
Maximum operating pressure may be obtained by
means of a cable operated from the instrument
panel to the lever arm on the valve. When reduced
load conditions require elevated control pressures,
the lever arm actuates the inner spring assembly
causing the piston to throttle in a closing direction.
This results in a higher evaporation pressure and
the desired increase in discharge air temperature.
C O M P R E S S O R
The compressor is of basic double-action
piston design. Three horizontal double acting
pistons make up a six-cylinder compressor, and
are mounted axially around the compressor shaft
to operate in a front and rear cylinder assembly.
These pistons operate in a 1-1/2" bore, have a
1-3/16" stroke and are actuated by a swash plate
pressed on the compressor crankshaft (see fig. 9).
Reed-type suction and discharge valves are
mounted in valve plates between the cylinder as­
sembly and the head at each end of the compressor.
The heads are connected with each other by gas-
tight passage ways which direct refrigerant gas to
a common output.
CHEVROLET SERIES 70 -80 H EAVY DUTY TRUCK SH O P M A N U A L