1973 OPEL GT-R tow

REFRIGERANT COMPONENTS ALL MODELS96.23Figure 96-l 3 Basic Refrigerant Circuit
we get the heat-laden vapor outside, we can com-
press it with a pump. With enough pressure, we can
squeeze the heat out of “cold” vapor even in a warm
room. An ordinary.radiator will help us get rid of
heat.
By removing the heat, and making the refrigerant
into a liquid, it becomes the same as it was before, So,
we can run another pipe back into the cabinet and
return the refrigerant to the flask to be used over
again.
That is the way most mechanical refrigerators work
today. Now, let’s look at an air conditioning unit to
see how closely it resembles the refrigerator we have
just described.
Basic Air ConditionerWhen we look at an air conditioning unit, we will
always find a set of coils or a tinned radiator core
through which the air to be cooled passes. This is
known as the “evaporator” (Fig.
9B-14). It does the
same job as the flask of refrigerant we
spok.e about
earlier. The refrigerant boils in the evaporator. In
boiling, of course, the refrigerant absorbs heat and
changes into a vapor. By piping this vapor outside
the car we can bodily carry out the heat that caused
its creation.
Once we get vapor out of the evaporator, all we haveFigure 98.14 Evaporator Assembly
to do is remove the heat it contains. Since heat is the
only thing that expanded the refrigerant from a liq-
uid to a vapor in the first place, removal of that same
heat will let the vapor condense into a liquid again.
Then we can return the liquid refrigerant to the
evaporator to be used over again.
Actually, the vapor coming out of the evaporator is
very cold. We know the liquid refrigerant boils at
temperatures considerably below freezing and that
the vapors arising from it are only a shade warmer
even though they do contain quantities of heat.
Consequently, we can’t expect to remove heat from
sub- freezing vapors by “cooling” them in air tem-
peratures that usually range between 60 and 100
degrees heat refuses to
flow from a cold object
toward a warmer object.
But with a pump, we can squeeze the heat-laden
vapor into a smaller space. And, when we compress
the vapor, we also concentrate the heat it contains.
In this way, we can make the vapor hotter without
adding any heat. Then we can cool it in compara-
tively warm air.
That is the only responsibility of a compressor in an
air conditioning system (Fig.
9B-15). It is not in-
tended to be a pump just for circulating the refriger-
ant. Rather, its job is to exert pressure for two
reasons. Pressure makes the vapor hot enough to
cool off in warm air. At the same time, the compres-
sor raises the refrigerant’s pressure above the con-
densing point at the temperature of the surrounding
air so it will condense.
As the refrigerant leaves the compressor, it is still a
vapor although it is now quite hot and ready to give
up the heat that is absorbed in the evaporator. One
of the easiest ways to help refrigerant vapor dis-
charge its heat is to send it through a radiator- like
contrivance known as a condenser (Fig. 9B-16).
The condenser really is a very simple device having
no moving parts. It does exactly the same job as the
radiator in a typical steam-heating system. There,
the steam is nothing more than water vapor. In pass-
ing through the radiator, the steam gives up its heat
and condenses back into water.
The same action takes place in an air conditioning

REFRIGERANT COMPONENTS ALL MODELS9B- 2596.15
Figure 95.17 Float Type Flow Valve
enough to close the valve and stop the flow of refrig-
erant liquid.
For the sake of simplicity, we have described the
float and valve action as being in a sort of definite
wide open or tight shut condition. Actually, though,
the liquid level falls rather slowly as the refrigerant
boils away. Likewise, the float goes down gradually
and gradually opens the valve just a crack. New
refrigerant liquid barely seeps in through the
“cracked” valve. At such a slow rate of flow, it raises
the liquid level in the evaporator very slowly.
With that in mind, it is easy to see how it would be
possible for a stabilized condition to exist. By that,
we mean a condition wherein the valve would be/
DIAPHRAGMACTUATINGBACK.UP PLATE
PINS \
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PASSAGE
‘!!!ISEATSCkEEN:ARRIAGEORIFICE
AGE SPRINGIER ELEMENT:MOB”LBSPRING SEAT
OUTLET
W-16opened barely enough to allow just exactly the right
amount of refrigerant liquid to enter the freezer to
take the place of that leaving as a vapor.
Thermostatic Expansion ValveAutomotive air conditioning systems use a thermo-
static expansion valve in place of the float system.
Figure 9B-18 shows a cross-section of the valve
which consists primarily of the gas-filled power ele-
ment, body, actuating pins, seat and orifice. At the
high pressure liquid inlet is a tine mesh screen which
prevents dirt, tilings or other foreign matter from
entering the valve orifice.
When the valve is connected in the system, the high
pressure liquid refrigerant enters the valve through
the screen from the receiver-dehydrator (which acts
as a storage tank for the condensed refrigerant as it
leaves the condenser) and passes on to the seat and
orifice. Upon passing through the orifice the high
pressure liquid becomes low pressure liquid. The low
pressure liquid leaves the valve and flows into the
evaporator core where it absorbs heat from the
evaporator core and changes to a low pressure vapor,
and leaves the evaporator core as such. The power
element bulb is clamped to the low pressure vapor
line just beyond the outlet of the evaporator (Fig.
9B-20).The operation of the valve is quite simple. It is a
matter of controlling opposing forces produced by a
spring and the refrigerant pressures. For example:
The pressure in the power element is trying to push
the seat away from the orifice, while the spring is
trying to force the seat toward the orifice. These
opposing pressures are established in the design of
the valve so that during idle periods, i.e. when the
system is not operating, the spring force and the
refrigerant pressure in the cooling coil are always
Figure 9B-18 Thermostatic Expansion Valve
Figure
98.20 Expansion Valve Bulb Location

9B-76 1973 OPEL SERVICE MANUAL
race. If, for example a feeler gage reading of 0.009
inch results, a thrust race with a number “9”,
stamped on it should be selected.Thrust Race TableSERVICEID NO.THICK-
PART NO. ON RACE
NESS
6556000
0.0920
6556050
5.09656556055
5l/2.09706556060
6.0975
65560656
l/2.09806556070
7.0985
6556075
7l/2.09906556080
8.0995
6556085
8l/2.lOOO6556090
T/2,100s
65560959.lOlO
655610010,101s
655610510 l/2.10206556110
.10256556115
11111/2.10306556120
12.1035The selected thrust race will replace only the “zero”
outer rear thrust race. The remaining three “zero”
thrust races will remain as part of the cylinder assem-
bly.
13. Remove cylinder assembly from inside compress-
ing fixture (J-9397), place on top of compressing
fixture (see Figure 9B-133) and disassemble rear cyl-
inder from front cylinder using rubber mallet or
hammer and wood block.
14. Carefully disassemble one piston at a time from
front cylinder and lay piston, front and rear piston
drive balls and front “zero” shoe disc in respective
slot of parts tray (J-9402). To disassemble, rotatewash plate until piston is at highest point, raise awash plate approximately
l/2 inch and lift out pis-
ton and related parts, one at a time.
15. Remove outer rear ‘?ero” thrust race from shaft
and set it aside for future gaging procedures.
16. Remove previously selected outer rear thrust
race from parts tray, lightly coat with clear pe-
troleum jelly and assemble onto shaft.
Final Reassembly of Cylinder Assembly1. Reassemble piston rings (if service pistons) onto
pistons (ring scraper groove toward center of piston)
and rotate ring so that break or gap in ring can be
squeezed together when piston is being inserted into
cylinder bore.
2. Reassemble piston drive balls, “zero” and se-lected shoe discs onto No. “1” piston, and apply
clear petroleum jelly to piston pockets and shoe discs
so that balls and discs stick to piston. BE SURE to
reassemble balls and shoe discs into their specific
positions on front and rear of piston.
3. Rotate shaft and wash plate assembly until high
point of wash plate is over No. “1” cylinder bore.
Position No. “1” piston onto wash plate (see Figure9B-146) and lower the piston and wash plate so that
the front end (notched end) of the piston enters the
cylinder bore.XTED OUTER
/REAR ZERO
THRUST RACE
PISTON RINGGAP SHOULD BE
TOWARD
98-118Figure 98.146 Installing Piston Assembly in Front
Cvlinder Half - Service Pistons Shown
Figure 98.147 Compressing Front Piston Rings
-Service Pistons