ECO mode OPEL GT-R 1973 User Guide

6A- 21973 OPEL SERVICE MANUAL
ENGINE
CONTENTS
Subject
DESCRIPTION AND OPERATION:
EngineConstruction..........................................................
LubricationSystem............................................................
DIAGNOSIS:
Excessive Oil Consumption............................................NoisyValvesandLifters..................................................
MAINTENANCE AND ADJUSTMENTS:
Valve
LifterAdjustment..................................................
MAJOR REPAIR:
Engine Removal and Installation..................................
Engine
OilPanRemoval
andInstallation..................
Manifold, Cylinder Head, Valve Train and
Lifters................................................................................
Connecting Rod Bearings................................................
Crankshaft Bearings and Seals....................................
Piston, Rings and Connecting Rods............................
TimingChainCoverandTimingChain......................
Camshaft..............................................................................
Oil Pump Cover and Gears............................................
SPECIFICATIONS:
BoltTorque.Specifications
..............................................General Specifications......................................................
Engine Dimension and Fits............................................Page No.
6A- 2
6A- 4
6A- 6
6A- 6
6A- 7
6A- 86A-106A-126A-156A-166A-196A-236A-256A-266A-276A-286A-29
DESCRIPTION AND OPERATION
ENGINE CONSTRUCTION
Engine UsageThe 1.9 liter engine is standard equipment on all 1973
Opel
1900, Manta and GT models. This engine has
a compression ratio of
7.6:1 and operates on“regular” low lead grade fuel.
Engine ConstructionThe
cyfinderhead is made of high-grade chromium
grey cast iron. The valve guides are cast intergal with
the head. The overhead camshaft is supported in four
bearings in the cylinder head.Location of the
vzllve seats in combustion chamber
is above the center of cylinder bore. The spark plug
is positioned in the center and near the highest point
of combustion chamber. This arrangement provides
for short flame travel, uniform combustion and good
cold start prop&ties. Exhaust valves have seat in-serts of highly heat and water resisting material. The
head surface is alumetized and so are the seats of the
inlet v&es Alumetizing makes the valve heads
non- scaling and promotes long life. All engines have“rota-caps”.
The forged, five main bearing crankshaft has large-
diameter main and connecting rod bearing journals
with considerable overlap for vibration-free operat-
ion. T&metal bearing shells are used for main and
connecting rod bearings. The crankshaft end play is
controlled by the rear main bearing.

SE- 441973 OPEL SERVICE MANUAL
CARBURETOR AND THROTTLE LINKAGE
ALL MODELS
CONTENTS
Subject
DESCRIPTION AND OPERATION:
Carburetor
. . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .DIAGNOSIS:
Carburetor
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .MAINTENANCE AND ADJUSTMENTS:
Idle Speed and Mixture Adjustments
. . . . . . . . . . . . . . . . . . . . . . . .Fast Idle Speed Adjustment
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Throttle Linkage Adjustment
. . . . . . . . . . . . . . . , . , . . . . . . . . . . . . . . . . . . . . . .MAJOR REPAIR:
RemoveandInstallCarburetor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . I...Throttle Linkage Removal
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .OverhaulCarburetor
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .SPECIFICATIONS:
Carburetor
Specifications
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page No.
6E-44
6E-49
6E-50
6E-51
6E-51
6E-52
6E-53
6E-53
6E-58
DESCRIPTION AND OPERATION
CARBURETORThe two-barrel carburetor for all 1973 Opel1
19G0,Manta and GT models is a down-draft carburetor
with two barrels of 1.25 inch diameter each. It has
an automatic choke and a secondary valve operated
by a vacuum diaphragm, except when installed in an
Opel GT. In the GT, the secondary throttle valve is
operated by mechanical linkage from the primary
throttle valve.
The two-barrel carburetor consists of three main
parts
- throttle body, float chamber and air horn.
Each barrel is a separate system, but both barrels
discharge into a common inlet in the intake mani-
fold. The secondary barrel does not have a choke
valve or an accelerator pump. See Figure
6E-2.The throttle valve of the primary barrel is opened
through the throttle linkage. When the primary
throttle valve is almost open, at approximately half
of the maximum engine RPM, the secondary throttlevalve is opened by vacuum applied through a
vacuum diaphragm case. See Figure
6E-3. The sec-
ondary throttle valve on the GT model is opened by
mechanical linkage from the primary throttle shaft.
Choke SystemThe automatic choke is operated by a bi-metal
spring. The tension of the spring
- depending on
temperature of the heater coil
- decreases with rising
temperature and the choke valve opens progressively
until it is completely opened at engine operating tem-
perature. The choke valve is off-set so that choke
valve opening increases as air flow increases.
If the choke valve is closed, the throttle valve is
opened slightly to provide a fast idle speed. This is
done through a cam, abutment lever and throttle
connecting link. With the throttle valve opened
slightly, the vacuum during cranking can take effect
up to the choke valve, thereby drawing ample fuel
out of the main nozzle. See Figure
6E-4.With rising temperature of the heater coil, the choke

TUNE-UP
ALL MODELS
CONTENTS
Subject
DESCRIPTION AND OPERATION:
Purpose of a Tune-Up. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . .DIAGNOSIS: (Not Applicable)
MAINTENANCE AND ADJUSTMENTS:
EngineTune-UpMechanicalOperations. . . . . . . . . . . . . . . . . . . .
EngineTune-UpInstrumentChecks. . . . . . . . . . . . . . . . . . . . . . . . . . . .MAJOR REPAIR: (Not Applicable)
SPECIFICATIONS:
Tune-Uo Soecifications and Adjustments
. . . . . . . . . . . . . . . .Page No.6G-65
6G-6566-6766-68
DESCRIPTION AND OPERATION
PURPOSE OF TUNE-UP
The purpose of an engine tune-up is to restore powerand performance that may have been lost through,
loss of adjustment, wear, corrosion, or deterioration
of one or more parts or units. In the normal operat-
ion of an engine, these changes take place gradually
at quite a number of points so that it is seldom advis-able to attempt an improvement in performance by
correcting one or two items only. Time will be savedand more lasting results will be assured by following
a definite and thorough procedure of analysis and
correction of all items affecting power and perform-
ance. Because of Federal laws, limiting exhaust emis-sions, it is even more important that the engines
tune-up is done accurately, using the specifications
listed and the tune-up sticker found in each engine
compartment.
Economical, trouble free operation can better be as-sured if a complete tune-up is performed at first 4
months or
6,ooO miles of operation - then at 12
month or 12,000 mile intervals.
The parts or units which affect power and perform-
ance may be divided, into three groups (1) compres-sion, (2) ignition and (3) carburetion. The tune-up
procedure should cover these groups in the order
given. While the items affecting compression and
ignition may be handled according to individual
preference, correction of items in the carburetiongroup should not be attemplcu
ulllll all items in
compression and ignition have been satisfactorily
corrected.
MAINTENANCE AND ADJUSTMENTS
ENGINE TUNE-UP OPERATIONS
CompressionTo make sure hydrocarbon and carbon monoxide
emissions will be within limits, it is very important
that the adjustments be followed exactly.
The suggested procedure for engine tune-up is as
follows:1. Remove all spark plugs.
2. Position throttle and choke valve in full open posi-tion.
3. Connect jumper wire between distributor terminalof coil and ground on engine to avoid high tension
sparking while cranking engine.
4. Hook up starter remote control cable and turn
ignition switch to “on” position.
5. Firmly insert compression gage in spark plug port.Crank engine to obtain highest possible reading.

7C- 361973 OPEL SERVICE MANUAL
CONTENTS
Subject
DESCRIPTION AND OPERATION:
Description of the Opel Three-Speed Automatic,Transmission....................................................................
Principles of Operation....................................................
ComponentOperation
andLocation............................
Mechanical Operation......................................................
Hydraulic Control Units and Valves............................H,y&aulic Operation..........................................................
DIAGNOSIS:
Sequence for Trouble Diagnosis..................................
Checking
Procedures........................................................
ExternalOil
Leaks..............................................................
Trouble
DiagnosisChart..................................................
Hydraulic Pressure
Checks............................................
MAINTENANCE AND ADJUSTMENTS:
Detent Cable Adjustment..............................................
ServicingSelector
Lever..................................................
MAJOR REPAIR:
Transmission Removal and Installation
AllModels........................................................................
Removalof
OilPan............................................................
RemovalofValveBody....................................................
Removalof
ServoPiston................................................
Removalof
Selector
LeverandShaft........................
RemovalofModulatorAssembly..................................
RemovalofDetentValveAssembly............................
RemovalofExtensionHousing......................................
Removal of Speedometer Drive Gear, Governor
Body and Governor Hub..............................................
Removal of Converter Housing, Oil Pump, Reverse
and Second Clutch Assembly..................................
Removal of Third Clutch Assembly, Planetary
Carrier Assembly, Reaction Sun Gear and Drum
Assembly and Low Bank............................................
Disassembly, Inspection and Reassembly of
Converter Housing, Oil Pump and Reverse Clutch
Disassembly, Inspection and Reassembly of
SecondClutch
................................................................
Disassembly, Inspection and Reassembly of
ThirdClutch....................................................................
Disassembly, Inspection and Reassembly of
Planetary Carrier
............................................................Page No.7c- 377c- 387c- 447c- 487c- 487c- 64
7C- 81
7C- 81IC- 817c- 827c- 877c- 917c- 937c- 947c- 99.7c- 99
7c-1007c-loo
7&l 01
7c-102
7c-102
7c-103
7c-103
7c-104
7c-105
7c-111
7c-114
7c-118

Figure 7C-1 Quadrant In Park Position -Opel 1900
and Manta7C- 381973 OPEL SERVICE MANUAL
R
- Reverse enables the vehicle to be operated in a
reverse direction.
N
- Neutral position enables the engine to be
started and operated without driving the vehicle.
D
- Drive range is used for all normal driving
conditions and maximum economy and has three
gear ratios. Downshifts are available for passing
by depressing the accelerator partially at lower
car speeds and through the “detent” at higher car
speeds.
S or 2
- Second range adds new performance for
hilly terrain. It has the same starting ratio as Drive
range, but prevents the transmission from shifting
above second gear to retain second gear for
acceleration or engine braking as desired. Second
range can be selected at any vehicle speed, but
should not be used above the speed shown m the
Owner’s Manual. This is to prevent over-speeding
the engine. The transmission will shift to second
gear immediately and remain in second until the
vehicle speed or the throttle position is changed
to obtajn first gear operation in the same manner
as in Drive range.
L or 1
- Lo range can be selected at any vehicle speed,
but should not be used above the speed shown in the
Owner’s Manual. The transmission will shift to low
(1st) gear immediately and remain in 1st gear regard-
less of vehicle speed or throttle position. This is par-
ticularly beneficial for maintaining maximum engine
braking.
PRINCIPLES OF OPERATION
Torque ConverterThe torque converter acts as a coupling to transmit
engine torque, through oil, to the transmission power
train. It also multiplies the torque from the engine
under certain conditions of input and output speed.
Figure
7C-2 Quadrant in Park Position - GT Models
The quadrant has six positions indicated in the fol-
lowing order: (Opel 1900 and Manta) P,R,N,D,S,
and L (Figure
7C-1); and (GT) P,R,N,D,2, and 1
(Figure 7C- 2).The torque converter used in the Opel three speed
automatic transmission consists of three basic ele-
ments: the pump (driving member), the turbine
(driven or output member) and the stator (reaction
member). See Figure
7C-3. The converter cover is
welded to the pump to seal all three members in an
oil tilled housing.
P
- Park position enables the transmission output
shaft to be locked
- thus preventing the vehicle
from roling either forward or backward. Because
the output shaft is mechanically locked by a
parking
paw1 anchored in the extension housing,
the park position should not be selected until the
vehicle has come to a stop. The engine may be
started in the Park position.Whenever the engine is running, the converter pump
turns at engine speed and acts as a centrifugal pump,
picking up oil at its center, adding energy, and dis-
charging the oil at its outer rim between the blades.
The shape of the converter pump shells and blades
cause the oil to leave the pump spinning in a clock-
wise direction toward the blades of the turbine. Asthere is no mechanical connection between converterpump and turbine, the oil is the only driving force
and strikes the blades of the turbine, transferring the

7C-1341973 OPEL SERVICE MANUAL
Figure 7C-232
Torque Converter4. Rotate converter to check for free movement.
1. Place transmission on portable jack
2. Slide torque converter over stator shaft and input
shaft.3. Be sure that converter pump hub keyway is seated
into oil pump drive lugs and the distance “A” is
.20”to
.28”. See Figure 7C-232.
SPECIFICATIONS
GENERAL SPECIFICATIONS
Opel Three-Speed Automatic Transmission Fluid
RecommendationsUse DEXRON Automatic Transmission Fluid on/y
in all 1972 model Opel Automatic Transmissions
(GM part No. 1050568-69-70 or any other fluid hav-
ing DEXRON identifications).DEXIRON is an especially formulated automatic
transmission fluid designed to improve transmission
operation.
The oil pan should be drained and the strainer re-
placed every
24,ooO miles and fresh fluid added to
obtain the proper level on the dipstick. See subpara-
graph 2 for proper refill procedures. For cars sub-
jected to heavy city
traff%z during hot weather, or in
commercial use, when the engine is regularly idled
for long periods, the oil pan should be drained and
the strainer replaced every
12,ooO miles.
.
1.Checking and Adding FluidThe Opel three-speed automatic is designed to oper-
ate at the full mark on the dipstick at normal operat-
ing temperature (180 degrees F.) and should be
checked under these conditions. The normal operat-
ing temperature is obtained only after at least 15
miles of highway type driving or the equivalent of
city driving.
Fluid level should be checked at every engine oil
change.
The “FuIl” and “Add” marks on the trans-
mission dipstick indicate one (1)pint
difference. Todetermine proper fluid level, proceed as follows:
To determine proper level, proceed as follows:
1. With manual control lever in Park position start
engine. DO NOT RACE ENGINE. Move manual
control lever through each range.
2. Immediately check fluid level with selector lever
in Park, engine running, and vehicle on LEVEL
surface.At
t,his point, when a reading is made, fluid level on
the dipstick should be at the “FULL” mark.
3. If additional fluid is required, add fluid to the
“FULL” mark on the dipstick.
If the vehicle cannot be driven sufficiently to bring
the transmission to operating temperature and it

7C-1361973 OPEL SERVICE MANUALshould be secured to keep the front wheels in a
straight-ahead position.sand,. mud, or snow, move the selector lever from
“D” to “R” in a repeat pattern while simultaneously
applying moderate pressure to the accelerator. DoRocking Carnot race engine. Avoid spinning wheels when trying
If it becomes necessary to rock the car to free it fromto free the car.
Model DesignationsTrans.
converterReverse Clutch
ModelAssemblyPlates Required2nd Gear
Clutch3rd Gear Clutch
Plates Required
Plates RequiredOpel
1900
OG
GT
CIHInformation
Drive
(Composition Faced:
Drive3Drive3
Green
(Composition
Faced)(CompositionFaced)
Dot ofDriven (Steel)4Driven (Steel) 4
Driven (Steel) 4
PaintWaved1Waved1Waved.1Pressure1Pressure1Pressure1-.
Bolt Torque Specifications
Location
Oil Pan to Case......................................................................Transfer Plate to Valve Body............................................
ReinforcementPlatetoCase..............................................
ValveBodytoCase..............................................................
ServoCovertoCase............................................................
Modulator Assembly............................................................
ConverterHousingtoOilPump........................................
Converter Housing to Case................................................
Selector Lever Jam Nut......................................................
Governor Body to Governor..............................................
ExtensionHousing to Case................................................
Servo AdjustingBolt Lock Nut..........................................
Planetary Carrier Lock Plate..............................................
OilPressureCheckPlug......................................................
Flex Plate to Crankshaft......................................................
Converter to Flex Plate........................................................
ConverterHousingtoCylinderBlock..............................
intermediate Selector Lever to Console
Selector Lever Shaft........................................................
Rear Engine Support to Transmission
CaseExtension..................................................................
Outer Transmission Selector Lever to
TransmissionSelectorLeverShaft..............................
Oil Cooler Line Connector..................................................
Oil Cooler Line to Connector............................................
Oil Cooler Line to Oil Cooler Hose..................................
Oil Cooler Hose to Oil Cooler............................................
Torque
Lb.Ft.7-10
6-8
13.15
13.1516-1812.15
13.17
22.26
8-l 1
6-8
20.30
12.15
20.35
5-736.5
138.42
38.42
Thread
Size
5/16-18
l/6-20
5/16-18
5/16-18
5/16-18
5/16-18
5/16-18
l/4-20
3/8-l 6
18.20
18.22
13.1610-13
1 l-15
1 l-15
11.15

HEATER SYSTEM. OPEL 1900. MANTA9A- 11air is attained, as the water does not cool down in the
second part of the core.
A Water Outlet
B Water Inlet
The center lever actuates the two-stage blower mo-
tor.Lever positions:
Left to Center
- Motor Switched Off
Right of Center
- Lo Blower
Right
- Hi Blower
The lower lever opens and closes the air door which
channels the air flow to either the lower heater out-
lets or to the defroster outlets.
In the left lever position, the air inlet is closed. Up
to the center position, the air is directed
t,o the lower
heater outlets.
When moving the lever from center position towards
the right, the air flow to the lower
heatezr outlets is
reduced and increased to the defroster
csutlets.With the lever in its right position, the air is directed
to the defroster outlets only. For windshield defrost-
ing, all levers have to be moved to the right.
FUNCTION OF THE HEATER AND VENTILATION
SYSTEMThe engine hood is provided with slots in front of the
windshield. The air is directed through the slots into
the heater housing located in the engine compart-
ment, flows into the air distributor housing, and
from there to the lower heater outlets and,/or defros-
ter outlets, depending on the position of the control.
The two-stage blower motor is arranged in the heater
housing above the heater core and actuated by the
center control. The blower motor draws in the air
entering through the slots, blows the air through the
heater core into the air distributor housin:?, and from
there to the lower heater outlets and/or defroster
outlets, depending on the position of the lower con-
trol. See Figure 9A-32.
The heater valve regulates the flow of coolant
through the heater core, thereby varying
t:he temper-
ature of the air flow past the core.
The ventilation of vehicle interior is completed by a
draft-free air circulation pattern. Vent
slots are ar-
ranged below the back window which
are: connected
through channels to the rear quarter
iside panel.
From here, the inside air escapes into
the! open. TheFigure
9A-32 Air Flow
head wind (caused by the car traveling down the
road) promotes this process so that there is always
fresh air in vehicle interior.
On the Model 54 Station Wagon, there will be no air
outlets in the rear. For adequate flow-through type
ventilation, it will be necessary to open a rear win-
dow.Aside from the fresh air admission through the
heater system, two fresh air inlet nozzles are ar-
ranged in the center of the instrument panel. These
nozzles can be turned to direct the air flow in the
desired direction. In addition, rotary flaps allow the
regulation of the entering air or to shut off the air
completely.
These nozzles admit unheated fresh air only and
operate independent of the heater and defroster sys-
tem.
DIAGNOSIS
HEATER SYSTEM TROUBLE DIAGNOSIS
TROUBLETemperature of heated air at outlets too low.
CAUSE AND CORRECTIONCheck radiator cap for proper sealing action. Re-
place, if necessary.
Check for adequate coolant supply. If level is down,
correct cause of coolant loss and refill radiator.
Inspect hose for kinks. Relieve kink or replace hoses.
Check thermostat operation by measuring tempera-
ture of coolant at radiator. Temperature should be
within 5 degrees F. of thermostat rated value (189
degrees F.).

98.18 1973 OPEL SERVICE MANUAL
DESCRIPTION AND OPERATION
FUNDAMENTAL PRINCIPLES OF REFRIGERATION
We all know what air conditioning does for us, but
very few understand how or why it works. An air
conditioner is functionally very similar to a refrigera-
tor, so let’s take a look at refrigeration. A refrigerator
is a simple mechanism which, surprisingly enough,
works quite a bit like a tea-kettle boiling on a stove.
That may sound far-fetched, but there is more
similarity between the two than most of us would
suspect. In fact, a modern refrigerator can make ice-
cubes and keep food cool and fresh only because a
liquid called the refrigerant boils inside the freezer.
Of codrse everyone knows a boiling tea-kettle is
“hot” and a refrigerator is “cold”. However, this is
where most of us are apt to get confused. We usually
think of “cold” as a definite, positive condition. Ac-
tually though, there is no such thing as “cold”. The
only way we can define it is in a rather negative sort
of way by saying “cold” is simply the lack of heat
just as darkness is the lack of light. We can:t make
things cold directly. All we can do is remove some
of the heat they contain and they will become cold
as a result. And that is the main job of any ice-box
or refrigerator. Both are simply devices for removing
heat.
All substances contain some heat. Theoretically, the
lowest temperature that any substance could obtain
is 459 degrees Fahrenheit below Zero. This may be
called “Cold”, and anything warmer than this con-
tains heat. Since man has never succeeded in getting
all the heat out of an object, we must think about the
transfer of heat from one object to another when
talking about controlling temperatures.
Figure
96-1 Transfer of Heat
Transfer of HeatThe only thing that will attract heat is a colder ob-ject.
:Like water, which always flows down-hill, heat
always flows down a temperature scale
- from a
warm level down to a colder one. When we hold our
hands out toward the fireplace, heat flows from the
hot fire out to our cold hands (Fig.
9B-1). When we
make a snowball, heat always flows from our warm
hands to the colder snow. In an ice-box, the ice al-
ways is colder than the stored food, so heat naturally
is drawn out of the warm food by the colder ice.
Measurement of HeatEveryone thinks he knows how heat is measured.
Thermometers are used in most: homes. Whenever
we speak of temperature from now on, we will mean
Fahrenheit. They can tell how hot a substance is, but
they can’t tell us everything about heat.
Figure
98-2 Applied Temperature Alone is Not the
Sole Measurement of Heat
When we put a tea-kettle on a stove, we expect it to
get hotter and hotter until it finally boils. All during
the process, we can tell exactly how hot the water is
by means of a thermometer (Fig.
9B-2). However,
our thermometer will show us that the flame is just
as hot when we first put the tea-kettle on the stove
as it is when the water finally boils. Why doesn’t the
water boil immediately then? Also, why does it take
longer to boil a quart of water than a cupful? Obvi-
ously temperature isn’t the only measurement of
heat.
Even though heat is intangible, it can be measured by
quantity as well as intensity. It is recognized that
thermometers indicate only the intensity of heat. The
unit for measuring quantity of heat is specified as
that amount necessary to make 1 pound of water 1
degree warmer (Fig.
9B-3). We call this quantity of
heat a British Thermal Unit. Often it is abbreviated
to Btu.
Perhaps we can get a better idea of these two charac-

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