Opel 1900 1973, Service Manual, Page: 542 / 625

REFRIGERANT COMPONENTS ALL MODELS 33
That the attraction of the drying material for mois-
ture is so powerful that if the receiver is left open,
moisture will be drawn in from the outside air.
That just one drop of water added to the refrigerant
will start chemical changes that can result in corro-
sion and eventual breakdown of the chemicals in the
system. Hydrochloric acid is the result of an R-12
mixture with water.
That the smallest amount of air in the refrigeration
system may start reactions that can cause malfunc-
tions.
That the drying agent in the receiver-dehydrator is
Activated Silica Alumina (silica-gel).
That inert gas in the expansion valve capillary
line is carbon dioxide.
DESCRIPTION OF AIR CONDITIONING
C O M P O N E N T S
Compressor
The compressor is located in the engine compart-
ment. The purpose of the unit is to draw the low
from the evaporator and compress this
gas into a high temperature, high pressure gas. This
action will result in the refrigerant having a higher
temperature than the surrounding air.
The is of basic double action piston de-
sign. Three horizontal double acting pistons make up
a six cylinder compressor (See Figure The
pistons operate in inch bore and have a
inch stroke. A plate keyed to the shaft drives
the pistons. The shaft is belt driven through a mag-
netic clutch and pulley arrangement. An oil pump
mounted at the rear of the compressor picks up oil
from the
of the compressor and lubricates the
other internal parts of the compressor.
Reed type valves at each end of the compressor open
or close to control the flow of incoming and outgoing
refrigerant. Two gas tight passages interconnect
chambers of the front and rear heads so that there is
one common suction port, and one common dis-
charge port. The internal parts of the compressor
function, as follows:
1. Suction Valve Reed Discs and Discharge Valve
Plates The two suction valve reed discs and two
discharge valve plates (see Figure
operate in
a similar but opposite manner. The discs are com-
posed of three reeds and function to open when the
pistons are on the intake portion of their stroke
(downstroke), and close on the compression stroke.
The reeds allow low pressure gas to enter the cylin-
ders. The discharge valve plates also have three
reeds, however, they function to open when the pis-
tons are on the compression portion of their stroke
(upstroke), and close on the intake stroke. High pres-
sure gas exits from discharge ports in the discharge
valve plate. Three retainers riveted directly above the
reeds on the valve plate serve to limit the opening of
the reeds on the compression stroke.
SUCTION VALVE
DISCHARGE-VALVE PLATES
Figure Compressor Suction Valve Reed Discs
and Discharge Valve Plates
2. Front and Rear Heads The front and rear heads
(Figure
serve to channel the refrigerant into
and out of the cylinders. The front head is divided
into two separate passages and the rear head is di-
vided into three separate passages. The outer passage
on both the front and rear heads channels high pres-
sure gas from the discharge valve reeds. The middle
passage of the rear head also contains the port open-
ing to the superheat switch cavity. This opening in
the rear head permits the superheat switch to be
affected by suction gas pressure and suction gas tem-
perature for the operating protection of the compres-
sor. The inner passage on the rear head houses the
oil pump inner and outer rotors. A Teflon sealing
material is bonded to the sealing surfaces separating
the passages in the rear head.
rings are used to
affect a seal between the mating surfaces of the heads
and the shell. The front head suction and discharge
passages are connected to the suction and discharge
passages of the rear head by a discharge tube and
suction passage in the
body of the cylinder assembly.
A screen located in the suction port of the rear head
prevents foreign material from entering the circuit.
3. Oil Pump An internal tooth outer rotor and
external tooth inner rotor comprise the oil pump.
The pump works on the principle of a rotary type
pump. Oil is drawn up from oil reservoir in underside
of shell through the oil inlet tube (see Figure