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
98.40 1973 OPEL SERVICE MANUAL
2. Interconnect manifold and gage set (J-5725-01),
gage charging lines (J-5418) and gage adapters
(J-5420) to air conditioning system as shown in Figure
9B-40.3. Place transmission in “Park” for automatics and
in neutral for manuals. Apply hand brake.
4. Turn blower switch to the “Hi” position.
5. Turn temperature switch to “Max” position.
6. Run engine at 2000 RPM for ten (10) minutes with
car doors and windows closed and the hood up. Place
a high volume industrial type fan in front of radiator
if head pressure should exceed 250 psi and also at
high ambients to bring the pressures to within the
limits specified in the Functional Charts in Division
V.In the case of the Opel 1900 and the Manta, a ther-
mometer should be placed in a position to read the
temperature of the air discharging from the right-
hand A/C outlet. In case of the GT, a thermometer
should be placed in a position to read the tempera-
ture of the air discharging from the left-rear A/C
outlet.
HEATER-AIR CONDITIONER REFRIGERANT
CIRCUIT TROUBLE DIAGNOSIS GUIDE
Insufficient Cooling (Check Air Flow)
Normal Air Flow (Inspect system for visual defects.
Run functional tests.)
Discharge Air
- Normal Temp Check for air leaks
through dash, car body, windows, or from heater or
ventilators.
Discharge Air
- High Temp Check sight glass for
foaming and compressor clutch for engagement.
No Compressor Clutch Engagement Check connec-
tions at clutch switch, harness connectors, and check
clutch switch.
No Foaming Compare evaporator pressure to that
on functional test table.
Foaming System is probably low on refrigerant.
Check for leaks, repair, evacuate, and charge. If
foaming still occurs, check for restriction in refriger-
ant lines between condenser and receiver dehydrator.
Evaporator Pressure Normal Compare head pres-
sure to pressure on functional test table.
Evaporator Pressure Low Ice may be forming on
evaporator. Low volume of air discharging at A/C
outlet after system has been running above idle con-dition
,for approximately 15-30 min.utes. Discharging
air gradually elevating in temperature. Check expan-
sion valve. If valve isn’t permitting flow of liquid,
this will be indicated by a warm pipe out of the
evaporator. This may be caused by: 1) Clogged or
Plugged inlet screen in the expansion valve; 2)
Broken capillary line; or 3) Discharged temperature
bulb. If the valve is okay, the pipe out of the evapora-
tor will be cold.
Evaporator Pressure High Check the expansion
valve to determine if themobulb is making good con-
tact and is properly insulated. Operate engine at 2000
RPM with maximum air conditioning setting. If
evaporator pressure remains high, feel suction line.
If line feels frosty or extremely
(cold with relative
high ambient conditions, then partially cover the
condenser to obtain head pressures from 265 psi to
280 psi maximum. If evaporator pressure rises above
30 psi, change the expansion valve.
Also, check if compressor may be the cause due to
some internal or external mechanical trouble which
prevents reduction of pressure. Check for external
troubles, slipping belt, bad clutch and/or pulley, or
improper clutch engagement, before investigating
the compressor internally.
Head Pressure High Check for the following: Con-
denser air flow low, air in system, excessive refriger-
ant in system, restriction in condenser.Head.PressureLowRestriction in flow of refrigerant
to evaporator, or expansion valve plugged or defec-
tive.
Low Air Flow (Check blower operation and
evaporator. Check operation of controls.)
Ice BIocking Evaporator Run functional test. If
evaporator pressure is low, ice may form on evapora-
tor and reduce air flow.
Evaporator Pressure Low Ice may be forming on
evaporator. Low volume of air discharging at A/C
outlet after system has been running above idle con-
dition for approximately 15-30 minutes. Discharging
air gradually elevating in temperature. Check expan-
sion valve. If valve isn’t permitting flow of liquid,
this will be indicated by a warm pipe out of the
evaporator. This may be caused by: 1) Clogged or
plugged inlet screen in the expansion valve; 2)
Broken capillary line, or 3) Discharged temperature
bulb. If the valve is okay, the pipe out of the evapora-
tor will be cold.BlowerNot OperatingCheck for the following: Fuse
blown, blower switch defective, wire broken or loose
connection, poor ground connection, or blower mo-
tor defective.
96-52 1973 OPEL SERVICE MANUAL
REMOVAL AND INSTALLATION OF EVAPORATOR
AND EXPANSION VALVE. OPEL 1900 - MANTA
Removal
1. Remove negative battery cable from battery.
2. Remove left side of distributor duct, and in line
fuse. See Figure
9B-61.3. Remove glove box. See Figure
9B-62.Figure 96-64 Delay Restrictor
and Check Valve Hose
Assembly Location
5. Disconnect the delay restrictor and check valve
hose assembly from the vacuum cut-off switch and
disconnect the electrical wiring. See Figures 9B-63
and 64.
6. Remove evaporator inlet and outlet pipes re-
tainer and rubber grommet. See Figure
9B-65.Figure
98.62 Glove Box Removed
4. Discharge refrigerant from system. (Refer to
DISCHARGING SYSTEM) and disconnect refrig-
erant hose from evaporator outlet and pipe from
evaporator inlet and tape the open ends of the refrig-
erant lines and evaporator pipes. See Figure
9B-63.Figure
98.65 Inlet and Outlet Pipes retainer and
Rubber Grommet-Opel 1900 - Manta
Figure
98.63 Location of Refrigerant Hoses, Pipes,
Vacuum Cut Off Switch and Evaporator Attaching Bolt
(Left Side) - Opel 1900
- Manta
96-54 1973 OPEL SERVICE MANUAL
valve. The filter screen at the inlet port may be re-
placed. Remove screen by threading a lo-32 NF
screw into old filter screen. With a washer and a nut
on the screw arranged to work as a puller screw, hold
the body of the screw and turn the nut. Insert the
new filter screen into the inlet port and lightly tap
screen only enough to seat.
1. Install expansion valve using new o-rings during
installation. Lubricate o-rings prior to installation
using No. 525 viscosity oil.
2. Install evaporator assembly and case attaching
screws. See Figure 9B-70.3. Install blower motor assembly into case and se-
cure with attaching screws. See Figure
9B-69.4. Install finger guard shields and fan housing case.
See Figure
9B-69.5. Install resistor assembly and electrical connector.
Install blower motor connector. See Figure
9B-69.6. Install assembly into car carefully guiding
evaporator pipes up through cowl opening. See Fig-
ure
9B-71.Figure 93-7 1 Inlet and Outlet Pipes and O-Rings
-Opel 1900 Manta
7. Install two (2) upper attaching evaporator at-
taching nuts. See Figures 9B-66 and
9B-67.8. Install two (2) attaching case mounting bracket
to instrument panel screws. See Figure
9B-67.9. Connect two (2) drain hoses underneath evapora-
tor.10. Install evaporator inlet and outlet pipes retainer
and rubber grommet. See Figure
9B-65.11. Connect vacuum cut-off switch and electrical
wiring, making sure the delay restrictor and checkvalve hoses are installed correctly. See Figures
9B-63and 64.
.gB-72 Delay Restrictor and Check Valve Hose.Assembly
12. Install refrigerant hoses and pipes using new
o-rings on line fittings and evacuate system. Refer to
EVACUATING SYSTEM.
13. While system is being evacuated, install in-line
fuse and left side of distributor duct. See Figure 9B-
61.14. Install glove box.
15. Install negative battery cable and charge system.
Refer to CHARGING SYSTEM.
REMOVAL AND INSTALLATION OF CONDENSER
ASSEMBLY -OPEL 1900. MANTA
Removal
1. Remove negative battery cable from battery.
2. Remove air cleaner.
3. Discharge system. Refer to DISCHARGING
SYSTEM.
4. While system is discharging, remove lower radia-
tor hose from radiator and drain coolant into a suita-
ble container.
5. Remove fan shroud.
6. On vehicles with automatic transmission, un-
screw oil lines from connectors on lower radiator
tank and plug lines. It is essential that no dirt enters
the oil lines. When unscrewing oil lines, hold connec-
tors on lower radiator tank with pliers to avoid leak-
ages. Ensure that no dirt enters oil cooler.
7. Remove upper radiator hose from radiator.
8. Remove lower attaching nut and slide radiator
upward and out of engine compartment.
9. Remove inlet and outlet hoses from condenser
AIR CONDITIONER SYSTEM -OPEL 1900 - MANTA9B- 91FAN DOES NOT RUN Correct electrical fault.
FAN RUNS
- Check air velocity.
NOT OK Clean evaporator inlets.
Clean evaporator core.
Clean evaporator outlets.
OK Check refrigeration (refer to Refrigeration
Diagnosis Guide).
MAINTENANCE AND ADJUSTMENTS
ADJUSTMENT OF THERMOSTATIC SWITCHThe system makes use of a thermostatic switch with
a self-supporting air sensing capillary. This capillary
controls the switch by sensing the temperature of the
air leaving the evaporator fins.
Checking for Proper Operation
I. Install the gauge set and set up the vehicle as
described under FUNCTIONAL TESTING SYS-
TEM iti Refrigerant Components Section.
2. Movement of the temperature control knob
should result in a definite change in suction pressure
and cycling of the compressor clutch.
3. If compressor continues to operate regardless of
the knob adjustment, it indicates that the switch
points are fused, which will lead to evaporator
freeze- up. The switch should be replaced.
Adjusting Switch
If, after ihe foregoing checks, the switch seems to be
operating correctly, adjust for proper setting if neces-
sary, as
~follows:1. Set up car as described in FUNCTIONAL
TESTING SYSTEM in Refrigerant Components
Section.2. The suction side of the system, read on the low
pressure gauge, should pull down to the pressure
shown in the chart in SPECIFICATIONS in Refrig-
erant Components Section.
3. Remove the face plate retaining screws and
remove face plate assembly noting the position of the
air sensipg capillary so that it can be reinstalled in
the same location as when removed. See Figure 98.170. ,:Figure
98.170 Location of Air Sensing Capillary
4. Remove the thermostatic switch retaining screws
and remove switch. Remove the non-metal end plate
from the switch to gain access tq the switch adjusting
screw. Check the screw for stripped or otherwise
damaged threads.
5. If the low side pressure
was less than the pre-
scribed pressure at the end of each cooling cycle, turn
the adjusting screw a partial turn clockwise. See Fig-
ure
9B-171.Figure 9B-17 1 Adjusting
Thkmosfatic Switch
6. If the pressure was more than the prescribed
value, turn the adjusting screw counter-clockwise.
7. Reinstall switch end plate and install switch in
face plate. Install face plate on ,evaporator assembly
assuring that the air sensing
c&pillary has been re-
placed properly.
8. Check system performance. Fffurther adjustment
is needed, repeat steps 3 thru 7 until the correct
pressure is reached.
Do not attempt to run a performance test with the
face plate and switch removed
,from the evaporator
assembly
- inaccurate reading, will result. Always
replace the switch and face plate assemblies before
checking the system performance.
AIR CONDITIONER SYSTEM. OPEL 1900. MANTA9B- 93
2. Remove the left side of distributor duct, and the
in-line fuse. See Figure 9B-174.98.139Figure SB-174 Location of Distributor Duct (Left Side)
Retaining Screws
Figure SB-175 Removing Left Side Distributor Duct
3. Rembve the glove box assembly. See Figure 9B-
176.
4. Discharge refrigerant from system, (refer to DIS-
CHARGING SYSTEM) and disconnect refrigerant
hose from evaporator outlet and pipe from evapora-
tor inlet’and tape the open ends of the refrigerant
lines and evaporator pipes. See Figure
9B-178.5. Disconnect the delay restrictor and check valve
hose assembly from the vacuum cut-off switch and
disconnect the electrical wiring. See Figure
9B-180.6. Rempve evaporator inlet and outlet pipes re-
tainer and rubber grommet. See Figure
9B-178.Figure SB-176 Glove
Bdx Removed
Figure SB-178 Location of Refrigerant Hoses, Pipes,
Vacuum Cut Off Switch and Evaporator Attaching Bolt
(Left Side)
Figure 9B-180 Vacuum Hoses and Wiring
AIR CONDITIONER SYSTEM -OPEL 1900 - MANTA9B- 95
Figure 96.185 Evaporator Inlet and Outlet Pipes andO-Rings
7. Connect the 2 drain hoses underneath evapora-
tor.
8. Install evaporator inlet and outlet pipes retainer
and rubber grommet. See Figure
9B-178.
9. Connect vacuum cut-off switch and electrical
wiring,, making sure the delay restrictor and check
valve hose are installed correctly. See Figure
9B-180.
10. Install refrigerant hoses and pipes using new o-
rings on line fittings and evacuate system. Refer to
EVACUATING SYSTEM.
Il. While system is being evacuated install the in-line
fuse and left side of distributor duct. See Figure
9B-
174.
12. Install the glove box.
Figure 98.186 Delay Restrictor and Check Valve Hose
Assembly
Figure 9B-187 Fuse Block Connections
13. Install negative battery cable and charge the sys-
tem. Refer to CHARGING SYSTEM.