cooling OPEL GT-R 1973 Owner's Manual

REFRIGERANT COMPONENTS ALL MODELS
99.37
in front of the radiator so that it receives a high
volume of air flow. Air passing over the condenser
absorbs the heat from the high pressure gas and
causes the refrigerant to condense into a high pres-
sure liquid.Receiver. DehydratorThe receiver-dehydrator is located in the engine
compartment. The purpose of the receiver dehydra-
tor is two fold: the unit insures a solid column of
liquid refrigerant to the expansion valve at all times,
and also absorbs any moisture in the system that
might be present. A bag of desiccant (moisture ab-
sorbing material) is provided to absorb moisture. A
sight glass (see Figure 9B-33) permits visual check-
ing of the refrigerant flow for bubbles or foam. The
continuous appearance of bubbles or foam above an
ambient temperature of 70 degrees F. usually indi-
cates an inadequate refrigerant charge. Bubbles or
foam appearing at ambient temperatures below 70
degrees F. do not necessarily indicate an inadequate
charge and may appear even when the system is
operating properly. A filter screen in the unit pre-
vents foreign material from entering the remainder
of the system.
Expansion ValveThe expansion valve is mounted on the evaporator
core inside the passenger compartment. The function
of the expansion valve is to automatically regulate
SCREEN
lLCl98.30
Figure 98-34 Expansion Valvethe flow of refrigerant into the evaporator. The ex-
pansion valve is the dividing point in the system
between the high and low pressure liquid refrigerant.
A temperature sensing bulb is connected by a capil-
lary tube to the expansion valve (see Figure
9B-34).The temperature sensing bulb (clamped to the outlet
pipe on the evaporator) measures the temperature of
the evaporator outlet pipe and transmits the temper-
ature variations to the expansion valve (see Figure
9B-34). The capillary tube and bulb are tilled with
carbon dioxide and sealed to one side of the expan-
sion valve diaphragm.
An increase in temperature will cause the carbon
dioxide in the bulb and capillary tube to expand,
overcoming the spring pressure and pushing the dia-
phragm against the operating pins (see Figure 9B-
34). This in turn will force the valve off its seat.
When the refrigerant low pressure gas flowing
through the outlet pipe of the evaporator becomes
more than 6 degrees higher or warmer than the tem-
perature at which it originally began to vaporize or
boil, the expansion valve will autmotatically allow
more refrigerant to enter evaporator. If the tempera-
ture of the low pressure gas decreases to less than 6
degrees above the temperature at which it originally
began to vaporize or boil, the expansion valve will
automatically reduce the flow of refrigerant. Thus,
an increase or decrease in the flow of refrigerant
through the evaporator will result in an increase or
decrease in the cooling by the evaporator. The tem-
perature, humidity and volume of the air passing
over the evaporator affects the rate of absorption of
heat by the evaporator. As the ambient temperature
bulb calls for more or less refrigerant will increase or
decrease. When the air is very warm, the heat trans-
fer from the air to the refrigerant is great and a
greater quantity of refrigerant is required to maintain
the temperature at the evaporator pipe at the prede-
termined value. Conversely, cool days will result in
less heat transfer and thereby require lesser quanti-
ties of refrigerant to maintain the predetermined
temperature of the evaporator outlet pipe.
EvaporatorThe function of the evaporator is to cool and
dehumidify the air flow in the passenger compart-
ment. The evaporator assembly consists of an alumi-
num core enclosed in a reinforced plastic housing.
Two (2) water drain ports are located in the bottom
of the housing. Two refrigerant lines are connected
to the side of the evaporator core: one at the bottom
and one at the top. The expansion valve is attached
to the lower (inlet) pipe, the outlet pipe is attached
to the upper pipe. The temperature sensing bulb of
the expansion valve is clamped to the outlet pipe of
the evaporator core. The high pressure liquid refrig-
erant, after it is metered through the expansion
valve, passes into the evaporator core where it is
allowed to expand under reduced pressure. As a re-
sult of the reduced pressure the refrigerant begins to

9B-38 1973 OPEL SERVICE MANUAL
expand and return to the original gaseous state. To
accomplish this transformation it begins to boil.
The boiling action of the refrigerant demands heat.
To satisfy the demand for heat, the air passing over
the core gives up heat to the evaporator and is subse-
quently cooled.\
DIAGNOSIS
GENERAL INFORMATIONThe following is a brief description of the type of
sympton each refrigerant component will evidence if
a malfunction occurs:
Compressor malfunction will appear in one of four
ways: noise, seizure, leakage, or low discharge pres-
sure.Resonant compressor noises are not cause for alarm;
however, irregular noise or rattles may indicate
broken parts or excessive clearances due to wear. To
check seizure, de-energize the magnetic clutch and
check to see if drive plate can be rotated. If rotation
is impossible, compressor is seized. Low discharge
pressure may be due to a faulty internal seal of the
compressor, or a restriction in the compressor.
Low discharge pressure may also be due to an insuffi-
cient refrigerant charge or a restriction elsewhere in
the system. These possibilities should be checked
prior to servicing the compressor. If the compressor
is inoperative; but, is not seized, check to see if cur-
rent is being supplied to the magnetic clutch coil
terminals.
CondenserA condenser may malfunction in two ways: it may
leak, or it may be restricted. A condenser restriction
will result in excessive compressor discharge pres-
sure. If a partial restriction is present, sometimes ice
or frost will form immediately after the restriction as
the refrigerant expands after pas?ing through the re-
striction. If air flow through the condenser or radia-
tor is blocked, high discharge pressures will result.
During normal condenser operation, the outlet pipe
will be slightly cooler than the inlet pipe.
Receiver-DehydratorA receiver-dehydrator may fail due to a restriction
inside body of unit. A restriction at the inlet to the
receiver-dehydrator will cause high head pressures.
Outlet tube restrictions will be indicated by low headpressures. Outlet tube restrictions will be indicated
by
low head pressures and little or no cooling. An
excessively cold receiver-dehydrator outlet may be
indicative of a restriction.
Expansion ValveExpansion valve failures usually will be indicated by
low suction and discharge pressures, and insuff%ient
evaporator cooling. The failure is generally due to
malfunction of the power element and subsequent
closing of the valve. A less common cause of the
above symptom is a clogged inlet screen.
EvaporatorWhen the evaporator malfunctions, the trouble will
show up as inadequate supply of cool air. A partially
plugged core due to dirt or a faulty blower will gener-
ally be the cause.
Refrigerant Line Restrictions
Rest~rictions in the refrigerant lines will be indicated
as follows:
I. Suction Line - A restricted suction line will cause
low suction pressure at the compressor, low dis-
charge pressure and little or no cooling.
2. Discharge Line -A restriction in the discharge line
generally will cause the pressure relief valve to open.
3. Liquid Line
- A liquid line restriction will be evi-
denced by low discharge and suction pressure, and
insufficient cooling.
Use of Receiver-Dehydrator Sight Glass for
DiagnosisAt temperatures higher than 70 degrees F, the sight
glass may indicate whether the refrigerant charge is
sufficient. A shortage of liquid refrigerant is in-
dicated after about
five minutes of compressor oper-
ation by the appearance of slow-moving bubbles
(vapor) or a broken column of refrigerant under the
glass. Continuous bubbles may appear in a properly
charged system on a cool day. This is a normal situa-
tion. If the sight, glass is generally clear and perform-
ance is satisfactory, occasional bubbles do not
indicate refrigerant shortage.
If the sight glass consistently shows foaming or a
broken liquid column, it should be observed after
partially blocking the air to the condenser. If under
this condition the sight glass clears and the perform-
ance is otherwise satisfactory, the charge shall be
considered adequate.

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.

REFRIGERANT COMPONENTS ALL MODELS9a- 47
B. Connect center flexible line of gauge set to the
fitting on the valve.
C. Start engine, turn temperature control knob to full
cold position, set blower switch to Max Hi. Operate
engine for 10 minutes at 2000 RPM to stabilize sys-tem.D. With compressor operating, slowly open valve on
refrigerant can and allow refrigerant to flow into
system (through manifold gauge set) until liquid in-
dicator clears up and immediately shut off valve at
gauge set and on refrigerant can. Check weight of
can and valve assembly and record.
E. Add an additional 1 lb. of refrigerant by adding
refrigerant from the can just weighed until can is
empty. Attach another can and add refrigerant until
can and valve assembly weigh the same as recorded.
6. Close valves at refrigerant drum or
can,7. Test for leaks and make operational check of
system.
ADDING OIL TO THE SYSTEM (MAJOR
OVERHAUL)The oil in the refrigeration system does not remain
in the compressor during system operation, but cir-culates throughout the system. The compressor is
initially charged with 10 oz. of 525 viscosity oil.
After system has been in operation the oil content in
the compressor will vary depending on the engine
RPM and air conditioning load. At higher engine
RPM’s a lesser amount of oil will be retained in the
compressor reservoir. It is important that the total
system oil content does not vary from a total of10-l/2 oz. Excessive oil content will reduce cooling
capacity. Inadequate oil content may result in dam-
age to compressor moving parts.
The refrigeration system will not require adding of
oil unless there is an oil loss because of a ruptured
line, badly leaking compressor seal, replacement of
evaporator, compressor, receiver-dehydrator, or loss
due to a collision. Oil is generally added to the sys-
tem via the oil drain hole in the lower side of the
compressor for this condition. To add oil to the sys-
tem via the compressor, the compressor must be
removed. If no major loss of oil has occurred and a
component (condenser,receiver-dehydrator or
evaporator) is removed for servicing, the oil may be
added directly to the component. To add oil to a
component removed for servicing and when no ma-
jor loss has occurred, drain and measure oil in com-
ponent, then replace with a like amount. To add oil
to the system when a major loss of oil is evidenced,
or when the compressor is being serviced, remove
compressor, drain and measure oil, and replace oil
amount specified in the Oil Replacement Table.
OIL REP,‘LACEMENT TABLE
Condition
1. Major loss of oil and
a component (conden-
ser, receiver-dehydra-
tor, or evaporator)
has to be replaced.
Amount of Oil Drained
From Compressora. More than 4 oz.Amount of 525 Oil to Install
In Compressora. Amount drained from compressor,
plus amount for component
being replaced.
Evaporator
- Add 2 oz.
Condenser
- Add I oz.
Receiver-Dehydrator
- Add 1 oz.
b. Less than 4 oz.b. Install 6 oz., plus amount for
component being replaced as
shown above.
2. Compressor being
replaced with a
ser-vice replacement
compressor
- no major
oil loss.a. More than 1
l/2 oz.a. Same amount as drained from
compressor being replaced.
b. Less than 1
l/2 oz.b. Install 6 oz

r98-82 1973 OPEL SERVICE MANUAL
SPECIFICATIONS
Tightening Specifications
Part
Location
NutDrivePlateNut toCompressorShaft..............................
NutRear Head to Shell................................................................
CaPSchraderServiceValve......................................................
Compressor Specifications
Torque
Lb. Ft.
15
21
5Type
..............................................................................................Six Cylinder Axial Opposed
Make
............................................................................................................................Frigidaire
Effective Displacement (Cu. In.)
..........................................................................................
9.2Oil
..........................................................................................................................525 Viscosity
Oil Content (New)
....................................................................................................10 Fl. Oz.
Air Gap Between Clutch Drive Plate and Pulley
......................................0.022 to 0.057 In.
Clutch Type
................................................................................................................h4agnetic
Belt Tension
..............................................................................................1 lo-125 Lbs. Irritial
....................................................................................................................80 Lbs. Retension
Pipe and Hose Connection Torque Chart
Metal TubeThread andSteel TubingAluminum orNominal Torque
I
Outside Dia.Fitting SizeTorqueCopper TubingWrench Span
Lb. Ft.Torque
Lb. tit.
5-7
General SpecificationsThermostat Opening Temperature
.._.....,,,...__....,,.............................................................. 189
Capacity of Cooling System With Air Conditioner (Quarls)
.,,..___....___............... 6 (Approx.)Type of Refrigerant
.___,,,._...,.,,,.__.....,,,.......,,,,.......,,,...................,,,......,,,............ Refrigerant 12
Refrigerant Capacity (Fully Charged)
Opel
1900-Manta,,._....,,,,._...._.,,,,.......,,,........,,............................................................2 Lbs.
GT
,..__..,..,..__..,,,.......,,,,.......,,,........,,,.,......,,,,,......,,.,,........,,.......,,..........,,............... 2 l/4 Lbs.
Functional Test Procedures1. Place transmission in park for automatics and in
neutral for manuals. Apply hand brake.
2. Turn blower switch to HI position,
3. Turn temperature switch to MAX position-.
4. Run engine at 2000 RPM for ten (10) minutes with
car doors and windows closed and the hood up. Place
a commercial high volumn fan in front of condenser
if head pressure should exceed 250 psig.A commercial high volumn fan should be placed in
front of the condenser at high ambients to bring the
pressures to within the limits specified in the Func-
tional Charts. When testing the Opel 1900 and
Man& a thermometer should be placed in a position
to read the temperature of the air discharging from
the right-hand A/C outlet. When testing the GT, a
thermometer should be placed in a position to read
the temperature of the air discharging, from the left-
rear
,A /c outlet.

System controls are the AIR knob controlling the
three speed blower motor switch and the TEMP
knob which controls the setting of the thermostatic
switch. When operating this system, the heater must
be off for maximum cooling.DIAGNOSIS
TROUBLE DIAGNOSIS GUIDE
Air Knob
Insufficient CoolingTurning the AIR knob clockwise operates the three-
speed blower motor.CHECK AIR FLOW9B-90 1973 OPEL SERVICE MANUAL
AIR CONDITIONER SYSTEM
OPEL 1900
- MANTA
CONTENTS
Subject
DESCRIPTION AND OPERATION:
General Description of System
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...”Operation of Controls
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . .DIAGNOSIS:
DiagnosisGuide. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..“................... . . . . . . . . .MAINTENANCE AND ADJUSTMENT:
Adjustment of Thermostatic Switch
. . . . . . . . . . . . . . . . . . . . . . . . .MAJOR REPAIR:
Removal81InstallationBlowerSwitch. . . . . . . . . . . . . . . . . . . . . .Page No.
9B-90
9B-90
9B-90
9B-91
98-92Removal
& Installation Temperature Control Switch
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . * . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Removal
& Installation Resistor Assembly. . . . . . . . . . . . . .Removal
& Installation Blower Motor Assembly . .
SPECIFICATIONS:
Specifications
.,...,,.,,..~.,.,..,,......,.,....,.,........,......,........ ,, . . . . . . .
98-92
98-92
98-92
98-96
DESCRIPTION AND OPERATION
GENERAL DESCRIPTION OF SYSTEMThe air conditioner is intended to give maximum
cooling comfort within the vehicle. To do this, care-
ful attention must be given to the following Sections.
The system operates on recirculated air only and is
entirely independent of the vehicle heater.
Temp KnobThis knob may be regulated to control the degree of
cooling desired. Fully clockwise provides maximum
cooling; however, turning the knob to the center de-
tent position provides adequate cooling for highway
operation.
When maximum cooling is required, outside air
should not be admitted to the car.
Recirculated inside air is drawn into the unit, passed
through the evaporator core and into the car through
the adjustable outlets in the evaporator case.
Operation of ControlsWhen the unit is set for maximum cooling and the
vehicle is being driven continuously at highway
speeds or at elevations of
4,OOC!ft. or more, there is
a possibility of the formation of ice on the evaporator
core fins.

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 - GT96. 97
AIR CONDITIONER SYSTEM
GTCONTENTS
Subject
: DESCRIPTION AND OPERATION:
General Description of System
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Operation of Controls
. . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .DIAGNOSIS:
Diagnosis Guide
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .MAINTENANCE AND ADJUSTMENTS:
Adjustment of Thermostatic Switch
. . . . . . . . . . . . . . . . . . . . . . .MAJOR REPAIR:
Removal 8 Installation of Vacuum Switch.
Removal&InstallationBlowerSwitch. . . . . . . . . . . . . . . . . . . . . .Removal & Installation Temperature Control Switch
. . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . .
Removal&InstallationResistor Assembly. . . . . . . . . . . . . .Removal & Installation Blower Motor Assembly . .
SPECIFICATIONS:
Specifications
. . .
. . . . . . . . * . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Page No.
9BL 97
9Bi 97
9BL 98
98: 98
9B: 99
9B; 99
9B- 99
98~10098-101
9B-104
DESCRIPTION AND OPERATIONAir Knob
GENERAL DESCRIPTION OF SYSTEMTurning the AIR knob clockwise operates the three-
speed blower motor.
The air &mditioner is intended to give maximum
cooling comfort within the vehicle. To do this, care-
ful attention must be given to the following sections.
The system operates on recirculated air only and is
entirely @dependent of the vehicle heater.Temp Knob
Recirculated inside air is drawn into the unit, passed
through the evaporator core and into the car through
the adjustable outlets in the duct assembly.This knob may be regulated to cohtrol the degree of
cooling desired. Fully clock-wise provides maximum
cooling; however, turning the kndb to the center de-
tent position provides adequate cooling for highway
operation.
CONTROLSWhen maximum cooling is reqlired, outside air
should not be admitted to the car.
System c&trols are the AIR knob controlling the
three
spe&d blower motor switch and the TEMPWhen the unit is set for maximum cooling and the
vehicle is being driven continuously at highway
knob which controls the setting of the thermostaticspeeds or at elevations of 4,000 ft. or more, there is
switch. When operating this system, the heater musta possibility of the formation of ice on the evaporator
be off for maximum cooling.core tins.

98.98 1973 OPEL SERVICE MANUALDIAGNOSISTROUBLE DIAGNOSIS GUIDE
Insufficient Cooling
CHECK AIR FLOW
FAN 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 tins.
Checking for Proper Operation
1. Install the gauge set, and set up the vehicle as
described under FUNCTIONAL TESTING SYS-
TEM in 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 the 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 lowpressure gauge, should pull down to the pressure
shown in the chart in SPECIFICATIONS in Refrig-
erant Components Section.
3. Remove the duct assembly mtaining screws and
remove the duct assembly noting the position of the
air sensing capillary so that it can be reinstalled in
the same location as when removed. See Figure 9B-
190.Figure 98.190 Duct Assembly and Retaining Screws
Figure 9B-13 1 Duct Assembly
4. Remove the thermostatic switch retaining screws
and remove switch. Remove the non-metal end plate
from the switch to gain access to 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, turnthe adjusting screw a partial turn clockwise. See Fig-ure 9B-192.AIR CONDITIONER SYSTEM
- GT9B- 99
CONNECTOR
Figure 98.192 Adjusting Thermostatic Switch6. If the pressure was more than the prescribed
value, tuin 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 capillary has been re-
placed properly.
Figure 98-l 93 Vacuum Switch8. Check system performance. Iffurther adjustment
is needed, repeat steps 3 thru 7 until the correct
pressure is reached.
REMOVAL AND INSTALLATION OF BLOWER
SWITCHDo not attempt to run a performance test with the
duct assembly and switch removed from the
evaporator assembly
- inaccurate readings will re-
sult. Always replace the switch and duct assemblies
before c+ecking the system performance.
Removal
MAJOFi REPAIR
1. Remove the negative cable from the battery2. Remove the retaining screws from the duct as-
sembly. See Figure
9B-190.3. Remove 2 blower switch rejaining screws and
remove blower switch.
REMOVAL AND INSTALLATION OF VACUUM
SWITCH,
Installation
Ramoval~1. Remove right trim pad below instrument panel.
2. Rembve two (2) screws and unplug the vacuum
hose and electrical connector. See Figure
9B-193.1. Install the blower switch and
secure with two (2)
retaining screws.
2. Install the duct assembly retaining screws.
3. Install the negative battery cable.
Installation1. Install two (2) screws and plug in electrical con-
nector and connect the delay restrictor and checkvalve
hose assembly.
I
REMOVAL AND INSTALLATIDN:OF
TEMPERATURE CONTROL SWITCH
Removal2. Install right trim pad.I. Remove the negative battery cable.