Pontiac FIREBIRD 1972 Service Manual page 90

CUSTOM AIR CONDITIONING 1A-3 1
O I L PICK-UP TUBE
'
OIL'
1 I
THRUST FRONT
AND HOUSING
SUMP R E A R
/
CYLINDER BEAR'NG CYLINDER
H A L F THRUST HALF
RACE
Fig. 1A-25 Cross Section
SUCTION VALVES
A three-reed suction valve disc is assembled to both the
front and rear cylinder heads. These reeds open when the
pistons are on the intake portion of their stroke to allow
the low pressure vapor to flow into the cylinders.
When the pistons reverse and are on the compression
portion of their stroke, the reed valve closes against their
seats to prevent the high pressure vapor from being forced
into the low side of the system.
DISCHARGE VALVES
There are two discharge valve plate assemblies, each hav-
ing three reeds and retainers positioned to direct the high
pressure vapor from the cylinders into the outer annular
cavities of the front and rear head castings. When the
piston has completed its compression stroke and reverses
to the suction stroke, the high pressure vapor in the dis-
charge cavity causes the reeds to close, thus maintaining
the differential of pressure between the high and low pres-
sure areas.
-
Compressor Assembly
The suction cavity is in the center and idexes with the
suction reeds. The discharge cavity is around the outside
and indexes with the discharge reeds.
The superheat switch port opening allows the superheat
switch to be affected by suction gas pressure and tempera-
ture for operation of the low refrigerant protection system
which prevents compressor damage under low refrigerant
charge conditions. See LOW REFRIGERANT
CHARGE PROTECTION.
These cavities are sealed from each other with a teflon seal
molded onto the rear cylinder head. The discharge cavity
is sealed from the outside of the compressor by an O-ring
seal which rests in a chamfered relief in the cylinder head
and compresses against the compressor body.
Both cylinder heads are connected with each other; the
suction cavities by a flat suction crossover cover, the dis-
charge cavity by a tube pressed into each head. Service
discharge crossover tube assemblies are seated with O-
rings and spacefs.
OIL PUMP
CYLINDER HEAD
Each cylinder head contains suction and discharge cavi-
ties. In addition, the rear head contains an oil pump
cavity, in the center of the suction cavity, to house the oil
pump gears (which are driven by the compressor main-
shaft). The suction cavitv in the rear head also contains
An oil pump mounted at the rear of the compressor picks
up oil from the bottom of the compressor oil sump and
pumps it to the internal parts.
The multi-lobed oil pump gears are made of sintered iron.
The inner gear is the driver and has a "D" shaped hole in
the port opening to the superheat shut-off switch cavity. the center which fits over a matching "D" flat on the rear