1967 CHEVROLET CAMARO check oil

LUBRICATION 0-14

SAE 5W-30 oils may be used during periods when

temperatures of 32° and below are to be expected.

Types of Oils

In service, crankcase oils may form sludge and varnish

and under some conditions, corrosive acids unless pro-

tected against oxidation.

To minimize the formation of these harmful products

and to assure the use of oil best suited for present day

operating conditions, automobile manufacturers have de-

veloped a series of sequence tests designed to evaluate

the ability of any oil to properly lubricate automobile

engines.

It is recommended that only those oils which are

certified by their suppliers as meeting or exceeding the

maximum severity requirements of these sequence tests

(or GM Standard 4745-M) be used in Chevrolet engines.

Certified sequence tested oils will be described as such

on their containers.

Maintaining Oil Level

The oil gauge rod is marked "Full" and "Add Oil."

These notations have broad arrows pointing to the level

lines.
The oil level should be maintained between the

two lines, neither going above the "Full" line nor under

the "Add Oil" line. DO NOT OVERFILL. After operating

vehicle allow a few minutes for oil to return to crankcase

before checking oil level.

Check the oil level frequently and add oil when

necessary.

Oil and Filter Change Intervals

NOTE:
Under prolonged dusty driving condi-

tions,
it is recommended that these operations

be performed more often.

OIL

To insure continuation of best performance, low main-

tenance cost and long engine life, it is necessary to

change the crankcase oil whenever it becomes contami-

nated with harmful foreign materials. Under normal

driving conditions draining the crankcase and refilling

with fresh oil every 60 days or every 6000 miles which-

ever occurs first, is recommended.

It is always advisable to drain the crankcase only after

the engine has become thoroughly warmed up or reached

normal operating temperature. The benefit of draining is,

to a large extent, lost if the crankcase is drained when

the engine is cold, as some of the suspended foreign

material will cling to the sides of the oil pan and will not

drain out readily with the cold, slower moving oil.

OIL FILTER

Change engine oil filter every 6000 miles or every 6

months, whichever occurs first.

NOTE:
For Vehicles in heavy duty operation

involving continuous start-stop or prolonged idl-

ing, engine oil should be changed after 2500-

3000 miles of operation. The filter should be

changed after 5000-6000 miles of operation.
Crankcase Dilution

Probably the most serious phase of engine oil deterio-

ration is that of crankcase dilution which is the thinning

of the oil by fuel vapor leaking by pistons and rings and

mixing with the oil and by condensation of water on the

cylinder walls and crankcase.

Leakage of fuel, or fuel vapors, into the oil pan occurs

mostly during the "warming up" period when the fuel is

not thoroughly vaporized and burned. Water vapor enters

the crankcase through normal engine ventilation and

through exhaust gas blow-by. When the engine is not

completely warmed up, these vapors condense, combine

with the condensed fuel and exhaust gases and form acid

compounds in the crankcase.

As long as the gases and internal walls of the crank-

case are hot enough to keep water vapor from con-

densing, no harm will result. However, when the engine

is run in low temperatures moisture will collect and

unite with the gases formed by combustion resulting in

an acid formation. The acid thus formed is likely to

cause serious etching or pitting which will manifest itself

in excessively rapid wear on piston pins, camshaft

bearings and other moving parts of the engine, oftentimes

causing the owner to blame the car manufacturer or the

lubricating oil when in reality the trouble may be traced

back to the character of fuel used, or a condition of the

engine such as excessive blowby or improper carburetor

adjustment.

Automatic Control Devices to Minimize

Crankcase Dilution

All engines are equipped with automatic devices which

aid greatly in minimizing the danger of crankcase

dUution.

The thermostat, mounted in the cylinder head water

outlet, restricts the flow of water to the radiator until a

predetermined temperature is reached, thus minimizing

the length of time required to reach efficient operating

temperature, reducing the time that engine temperatures

are conducive to vapor condensation.

A water by-pass is included in the cooling system,

utilizing a hole in the front of, the cylinder block. This

allows a limited circulation of coolant, bypassing the

thermostat until thermostat opening temperatures are

reached. This system provides a uniform coolant tem-

perature throughout the engine, eliminating localized

hot-spots, improving exhaust valve life, provides fast

warmrup of lubricating oil and fast temperature rise in

the coolant which provides fast heater operation in cold

weather.

A thermostatic heat control on the exhaust manifold

during the warming up period, automatically directs the

hot exhaust gases against the center of the intake mani-

fold, greatly aids in proper vaporization of the fuel.

An automatic choke reduces the danger of raw or

unvaporized fuel entering the combustion chamber and

leaking into the oil reservoir.

An.
efficient crankcase ventilating system drives off

fuel vapors and aids in the evaporation of the raw fuel

and water which may find its way into the oil pan.

CRANKCASE BREATHER CAP

Clean and re-oil at every oil change..

CHEVROLET CHASSIS SERVICE MANUAL

LUBRICATION 0-15

CRANKCASE VENTILATION VALVE

VALVE TYPE

NOTE: Under prolonged dusty driving condi-

tions,
it is recommended that these operations

be performed more often. Every 12,000 miles

or 12 months the valve should be replaced.

Connecting hoses, fittings, flame arrestor and

crankcase breather cap (where used) should be

cleaned. At every oil change the system should

be tested for proper function and serviced, if

necessary.

FUEL FILTER

Replace filter element located in carburetor inlet if

flooding occurs, if engine surges during constant speed

operation (pulsating effect) or if poor performance is

experienced during acceleration or at higher speeds.

AIR CLEANER

NOTE: Under prolonged dusty driving condi-

tions,
it is recommended that these operations

be performed more often.

POLYURETHANE TYPE-

Every 12,000 miles clean element in solvent, squeeze

out solvent, then soak in engine oil and squeeze out

excess.

OIL WETTED PAPER ELEMENT TYPE-

First 12,000 miles inspect or test element; if satis-

factory, re-use element but recheck every 6,000 miles

until replaced. Element must not be washed, oiled,

tapped or cleaned with an air hose.

BATTERY TERMINAL WASHERS

Battery terminals have felt washers between top of

case and cable connections to minimize corrosive action

of battery acid. These felt washers should be saturated

with engine oil every 6,000 miles.

DISTRIBUTOR

4 and 6-Cylinder Engine—Remove distributor cap and

rotate lubricator 1/2 turn at 12,000 mile intervals. Re-

place at 24,000 mile intervals.

8-Cylinder Engine—Change cam lubricator end for end

at 12,000 mile intervals. Replace at 24,000 mile

intervals.

REAR AXLE AND 3-SPEED AND

OVERDRIVE, 4-SPEED TRANSMISSIONS

The passenger car operates under the most severe

lubrication conditions at high speed and requires a hypoid

lubricant which will meet this condition.

Recommended Lubricants

Standard Rear Axles—SAE 90 "Multi-Purpose" gear

lubricant.

Positraction Rear Axles—Use special Positraction

lubricant.
CAUTION: Straight Mineral Oil gear lubricants

must not be used in hypoid rear axles.

Transmissions—SAE 90 "Multi-Purpose" gear

lubricant.

The SAE 90 viscosity grade is recommended for year

round use. However, when extremely low temperatures

are encountered for protracted periods during the winter

months, the SAE 80 viscosity grade may be used.

"Multi-Purpose" Gear Lubricants

Gear lubricants that will satisfactorily lubricate hypoid

rear axles have been developed and are commonly re-

ferred to as ' 'Multi-Purpose" gear lubricants meeting

U.S.
Army Ord. Spec. MIL-L-2105B.

These lubricants can also be satisfactorily used in

manual transmissions.

CAUTION: With Positraction rear axles use

special Positraction lubricant.

"Multi-Purpose" gear lubricants must be manufac-

tured under carefully controlled conditions and the

lubricant manufacturer must be responsible for the

satisfactory performance of his product. His reputation

is the best indication of quality.

Lubricant Additions

The lubricant level in the axle and transmission hous-

ings should be checked periodically. (Every 6,000 miles.)

It is recommended that any additions required to bring

up the lubricant level be made using the same type lubri-

cant already in the housing.

When checking lubricant level in transmission or rear

axle the unit being cheeked should be at operating

temperature. With unit at operating temperature the

lubricant should be level with bottom of the filler plug

hole.
If the lubricant level is checked with the unit cold

the lubricant level should be 1/2 inch below the filler

plug hole.

Lubricant Changes

The rear axle lubricant does not require changing for

the life of the vehicle. If additions are needed, or when

refilling the axle after service procedures, use lubricants

described above.

POWERGLIDE TRANSMISSION

NOTE: Every 12,000 miles, it is recommended

that the Powerglide low band be adjusted as

specified in Section 7 of this manual.

Every 6,000 miles--Check fluid level on dipstick with

engine idling, selector lever in neutral position, parking

brake set and transmission at operating temperature. If

fluid level is below full mark on dip stick, adding a small

amount of Automatic Transmission Fluid, General Motors

Automatic Transmission Fluid (Part Numbers 1050568-

69,
70) is recommended. If this fluid is not obtainable,

use Automatic Transmission Fluid Type 'A' bearing the

mark AQ-ATF followed by a number and the suffix letter

'A'.
Recheck fluid level on dip stick and again add a

small amount of fluid if needed to bring level to full

mark. DO NOT OVERFILL.

CHEVROLET CHASSIS SERVICE MANUAL

HEATER
AND AIR
CONDITIONING
1A-13

AIR CONDITIONING

INDEX

Page

General Description
1A-13

Four-Season System
1A-13

Controls
1A-16

Comfortron System
. 1A-18

System Components
lA-19

Controls
1A-20

Universal System
. .
1A-21

Chevy
n
All-Weather System
•
1A-21

Corvette Four-Season System
. 1A-22

General Information
. . . 1A-26

Precautions
in
Handling R-12
1A-26

Precautions
in
Handling Refrigerant Lines
1A-28

Maintaining Chemical Stability
in the

Refrigeration System
1A-28

Gauge
Set 1A-29

Charging Station
IA-29

Leak Testing
the
System
1A-29

Vacuum Pump
1A-30

Availability
of
Refrigerant-12
. . 1A-30

Compressor
Oil 1A-31

Compressor Serial Number
1A-31

Inspection
and
Periodic Service
1A-31

Pre-Delivery Inspection
1A-31

6,000 Mile Inspection
1A-32

Periodic Service
, 1A-32

Installing Gauge
Set to
Check System Operation
....
1A-32

Performance Test
1A-32

Performance Data lA-r33

Comfortron System Operational Test
1A-33

Chevrolet Comfortron Tester
1A-34

Complete System Checks
1A-35

Maintenance
and
Adjustments ......
1A-37

Evaporator Comtrol Valve (POA)
.
1A-37
Page

Thermostatic Switch
1A-37

Expansion Valve
1A-41

Engine Idle Compensator
. . .
1A-42

Evacuating
and
Charging Procedures
1A-42

Purging
the
System
1A-42

Evacuating
and
Charging
the
System
1A-43

Checking
Oil . 1A-43

Component Replacement
and
Minor Repair
1A-45

Refrigerant Line Connections
1A-45

Repair
of
Refrigerant Leaks
1A-46

Preparing System
for
Replacement
of

Component Parts
. 1A-46

Foreign Material
in the
System
.
1A-47

Condenser
.
1A-48

Receiver-Dehydrator
1A-48

Evaporator
1A-49

Expansion Valve
1A-57

Evaporator Control Valve (POA)
1A-59

Thermostatic Switch
or
Blower Switch
. .
1A-59

All Weather-Pull Cable
1A-61

Blower Assembly
1A-62

Air Inlet Valve
.
1A-64

Blower
and
Evaporator Assembly
1A-64

Air Distributor Assembly
and
Outlet Ducts ...... 1A-64

Comfortron Automatic Control Components
1A-66

Collision Procedure lA-70

Four-Season Heater Components
1A-73

Comfortron Heater Components
. . . 1A-75

Compressor
1A-76

Wiring Diagrams
1A-78

Special Tools
.
1A-84

GENERAL DESCRIPTION

Four
air
conditioning systems
are
covered
in
this

section. They are:

1.
The
Four-Season System (Chevrolet, Chevelle,

Camaro and Corvette).

2.
The Comfortron System (Chevrolet).

3.
The All Weather System (Chevy n).

4.
The Universal System (Chevrolet, Chevelle, Chevy
n,

Camaro)

Underhood components (that
is, the
compressor,
con-

denser
and
receiver-dehydrator)
are
much
the
same
in

type,
location
and
method
of
attachment
on all of
the

above systems. The six-cylinder reciprocating compres-

sor
is
bracket-mounted
to the
engine
and
belt driven

from
the
crankshaft pulley.
The
condenser
is
mounted

ahead
of the
engine cooling radiator
and the
receiver-

dehydrator
is
mounted
in
the refrigerant line downstream

of
the
condenser.
All
cooling system components
are

connected by means
of
flexible refrigerant lines.

Evaporator size
and
location differ from system
to

system
as do
methods
of
temperature control
and air

supply
and
distribution.

FOUR-SEASON SYSTEM

The Four-Season system used
in the
Chevrolet,

Chevelle, Camaro,
and
Corvette vehicles
may be
iden-

tified
by the
fact that
it
uses
an
evaporator pressure

control known
as the POA
(Pressure Operated Absolute)

suction throttling valve.
Both
the
heating
and
cooling functions
are
performed

by this system.
Air
entering
the
vehicle must pass

through
the
cooling unit (evaporator)
and
through
(or

around)
the
heating unit,
in
that order, and the system
is

thus referred to
as a
''reheat" system.

The evaporator provides maximum cooling
of the air

passing through
the
core when
the air
conditioning sys-

tem
is
calling
for
cooling.
The
control valve acts in the

system only
to
control
the
evaporator pressure
so
that

minimum possible temperature
is
achieved without core

freeze-up.
The
valve
is
preset,
has no
manual con-

trol,
is
automatically altitude compensated,
and non-

repairable.

The heater core will be hot
at
all times since no water

valve
is
present
in
the system.

System operation
is as
follows (See Figure 24 and 25):

Air, either outside
air or
recirculated
air
enters
the

system
and is
forced through
the
system by the blower.

As
the air
passes through
the
evaporator core,
it

receives maximum cooling
if
the
air
conditioning controls

are calling
for
cooling. After leaving
the
evaporator,

the
air
enters
the
Heater
and Air
Conditioner Selector

Duct Assembly where,
by
means
of
manually operated

diverter doors,
it is
caused
to
pass through
or to
bypass

the heater core
in the
proportions necessary
to
provide

the desired outlet temperature. Conditioned airflow then

enters
the
vehicle through either
the
floor distributor

duct
or the
dash outlets. Remember that the heater core

CHEVROLET CHASSIS SERVICE MANUAL

HEATER AND AIR CONDITIONING 1A-29

time as possible will be required to perform the

operation. Don't leave the system open any longer

than is necessary.

• Finally, after the operation has been completed and

the system sealed again, air and moisture should be

evacuated from the system before recharging.

GAUGE SET

The gauge set (fig. 41) is used when purging, evacua-

ting, charging or diagnosing trouble in the system. The

gauge at the left is known as the low pressure gauge.

The face is graduated into pounds of pressure and, in

the opposite direction, in inches of vacuum. This is the

gauge that should always be used in checking pressures

on the low pressure side of the system. When all parts of

the system are functioning properly the refrigerant

pressure on the low pressure side never fails below 0

pounds pressure. However, several abnormal conditions

can occur that will cause the low pressure to fall into a

partial vacuum. Therefore, a low pressure gauge is

required.

The high pressure gauge is used for checking pres-

sures on the high pressure side of the system.

The connection at the left is for attaching the low

pressure gauge line and the one at the right the high

pressure gauge line. The center connector is common to

both and is for the purpose of attaching a line for adding

refrigerant, discharging refrigerant, evacuating the sys-

tem and other uses. When not required, this line or

connection should be capped.

NOTE:
Gauge fitting connections should be in-

stalled hand tight only and the connections leak

tested before proceeding.

The hand shutoff valves on the gauge manifold do not

control the opening or closing off of pressure to the

gauges. They merely close each opening to the center

connector and to each other. During most diagnosing

and service operation, the valves must be closed. The

only occasion for opening both at the same time would be

to bypass refrigerant vapor from the high pressure to

the low pressure side of the system, or in evacuating

both sides of the system.

CHARGING STATION

The J-8393 Charging Station is a portable assembly of

a vacuum pump, refrigerant supply, gauges, valves, and

most important, a five (5) pound metering refrigerant

charging cylinder. The use of a charging ey'inder elim-

inates the need for scales, hot water pails, etc.

The chief advantage of this unit is savings. A very

definite savings in refrigerant and time can be obtained

by using this unit. Since the refrigerant is metered into

the system by volume, the correct amount may be added

to.
the system and charged to the customer. This, coupled

with the fact that the unit remains "plumbed" at all times

and thus eliminates loss of refrigerant in purging of

lines and hooking-up, combines to enable the operator to

get full use of all refrigerant purchased by the

dealership.

All evacuation and charging equipment is hooked to-

gether in a compact portable unit (fig. 42) which brings

air conditioning service down to the basic problem of

hooking on two hoses, and manipulating clearly labeled

valves.
Fig.
42—System Charging Station

This will tend to insure that the job will be done without

skipping operations. As a result, you can expect to save

time and get higher quality work, less chance of an over

or undercharge, or comeback.

The pump mount is such that the dealer may use his

own vacuum pump. The gauges and manifold are in com-

mon use. Thus a current air conditioning dealer can use

the equipment on hand and avoid duplication.

LEAK TESTING THE SYSTEM

Whenever a refrigerant leak is suspected in the system

or a service operation performed which results in dis-

turbing lines or connections, it is advisable to test for

leaks.
Common sense should be the governing factor in

performing any leak test, since the necessity and extent

of any such test will, in general, depend upon the nature

of the complaint and the type of service performed on

the system. It is better to test and be sure, if in doubt,

than to risk the possibility of having to do the job over

again.

NOTE:
The use of a leak detecting dye within

the system is not recommended because of the

following reasons:

1.
Refrigerant leakage can exist without any oil leakage.

In this case the dye will not indicate the leak, how-

ever, a torch detector will.

2.
The addition of additives, other than inhibitors, may

alter the stability of the refrigeration system and

cause malfunctions.

3.
Dye type leak detectors which are insoluble form a

curdle which can block the inlet screen of the ex-

pansion valve.

CHEVROLET CHASSIS SERVICE MANUAL

HEATER
AND AIR
CONDITIONING
1A-31

FIVE
AMP

TIME DELAY

FUSE

CORD
TO

110
AC
SOURCE
PUMP

INLET
PUMP DISCHARGE

OUTLET

Fig.
44—Vacuum Pump

the use of weighing equipment necessary with the larger

drum. The single can Valve J-6271 can be used for com-

pleting the charge and for miscellaneous operations such
Fig.
45-R-12 Disposable Cans

as flushing. The valves are installed by piercing the top

seal of the cans.

Evacuating and charging procedures later in this sec-

tion will make use of the J-8393 Charging Station which

uses the 25 lb. drum of refrigerant.

COMPRESSOR OIL

Special refrigeration lubricant should be used in the

system. It is available in 1 quart graduated bottles

through Parts Stock. This oil is as free from moisture

and contaminants as it is possible to attain by commercial

processes. This condition should be preserved by im-

mediately capping the bottle when not in use.

See "Air Conditioning System Capacities" for the

total system oil capacity.

Due to the porosity of the refrigerant hoses and con-

nections, the system refrigerant level will show a definite

drop after a period of time. Since the compressor oil is

carried throughout the entire system mixed with the

refrigerant a low refrigerant level will cause a dangerous

lack of lubrication. Therefore the refrigerant charge in

the system has a definite tie-in with the amount of oil

found in the compressor and an insufficient charge may

eventually lead to an oil build-up in the evaporator.

COMPRESSOR SERIAL NUMBER

The compressor serial number is located on the serial

number plate on top of the compressor. The serial num-

ber consists of a series of numbers and letters. This

serial number should be referenced on all forms and

correspondence related to the servicing of this part.

INSPECTION AND PERIODIC SERVICE

PRE-DELIVERY INSPECTION

1.
Check that engine exhaust is suitably ventilated.

2.
Check the belt for proper tension.

3.
With controls positioned for operation of the system,

operate the unit for ten minutes at approximately

2000 rpm. Observe the clutch pulley bolt to see that

compressor is operating at the same speed as the
clutch pulley. Any speed variation indicates clutch

slippage.

Before turning off the engine, check the sight glass

to see that the.unit has a sufficient Refrigerant

charge. The glass should be clear, although during

milder weather it may show traces of bubbles. Foam

in.
the flow indicates a low charge. No liquid visible

indicates no charge.

CHEVROLET CHASSIS SERVICE MANUAL

HEATER AND AIR CONDITIONING 1A-32

5.
Check hose clamp connections. If clamp screw torque

is less than 10 lb. in., retighten to 20-25 lb. in. Do

not tighten to new hose specifications or hose leak-

age may occur.

6. If there is evidence of an oil leak, check the com-

pressor to see that the oil charge is satisfactory.

7.
Check the system controls for proper operation.

6000 MILE INSPECTION

1.
Check unit for any indication of a refrigerant leak.

2.
If there is an indication of an oil leak, check the

compressor proper oil charge.

3.
Check sight glass for proper charge of Refrigerant-

12.

4.
Tighten the compressor brace and support bolts and

check the belt tension.

5.
Check hose clamp connections as in step 5 above.

6. Check thermostatic switch setting (Universal and

All-Weather Systems.)

PERIODIC SERVICE

• Inspect condenser regularly to be sure that it is not

plugged with leaves or other foreign material.

Fig.
46—Compressor Connector Block—Typical
• Check evaporator drain tubes regularly for dirt or

restrictions.

• At least once a year, check the system for proper

refrigerant charge and the flexible hoses for brittle-

ness,
wear or leaks.

• Every 6000 miles check sight glass for low refriger-

ant level.

• Check belt tension regularly.

• Every week - during winter months or other periods

when the system is not being operated regularly- run

the system, set for maximum cooling, for 10 or 15

minutes to insure proper lubrication of seals and

moving parts.

INSTALLING GAUGE SET TO CHECK

SYSTEM OPERATION

Compressor Suction and Discharge Connector

Compressor connector assemblies used on all vehicles

are of the same basic design consisting of the inlet

(suction) and outlet (discharge) connections, gauge fittings

and muffler and, in general, the assemblies differ only in

the location of the gauge fittings.

On Universal and Four-Season Systems the outlet line

extends along side of and toward the front of the com-

pressor and the muffler in the line is bracket mounted to

the compressor body. In all Universal Systems the gauge

fittings for both low and high pressure sides of the sys-

tem are located in the connector body. On Four-Season

Systems the high pressure gauge fitting is located on the

muffler and the low pressure gauge fitting is on the POA

Valve.

The Chevy n All-Weather System compressor con-

nector assembly is similar to the Universal System

connector assembly described above except that the

muffler extends straight out from the connector and

is not bracket mounted to the compressor.

Universal and Chevy II All-Weather System

1.
Install Gauge Adapter (J-5420 or J-9459) onto the

high and low pressure hoses of the gauge set.

2.
With the engine stopped, remove the caps from the

cored valve gauge, connectors on the compressor

fittings block.

3.
Connect the gauge lines with adapters to the threaded

connectors on the compressor fittings block.

Four-Season and Comfortron Systems

Installation of the gauge set onto the Four-Season and

Comfortron systems is accomplished in the same manner

as outlined above except that system performance checks

must be performed with the low pressure hose line and

adapter attached to the fitting on the POA valve. Charging

procedures should be performed with the high pressure

gauge line connected to the high pressure gauge fitting

located on the outlet line muffler and the low pressure

gauge line attached to the POA fitting.

CAUTION: When removing gauge lines from

the compressor fittings block be sure to remove

the adapters from the fittings rather than the

gauge lines from the adapters.

PERFORMANCE TEST

This test may be conducted to determine if the system

is performing in a satisfactory manner and should be

used as a guide by the serviceman in diagnosing trouble

CHEVROLET CHASSIS SERVICE MANUAL

HEATER AND AIR CONDITIONING 1A-37

VACUUM SYSTEM COMPONENT FUNCTION

Component

Air Door Diaphragm

Power Servo

Vacuum Relay Valve

Mode Door Diaphragm

Defroster Diaphragm

Transducer

Thermo Vacuum Valve
Vacuum Applied

Air Door Open to Outside Air

(Closed to Car Body)

Maximum Heat

Vacuum Applied to One Port Opens a Passage

Through the Valve to Allow Transducer Vacuum

to be Supplied to the Power Servo

Vacuum to Linkage Side

Air Flow Out Heater

Ducts

Full Airflow Out Heater

Outlet
Vacuum to Covered Side

Airflow Out of Upper

Outlets

Full Airflow Out Defroster

Outlets (Full De-ice)
No Vacuum Applied

Air Door Open to

Re circulated Air

(Open to Car Body)

Maximum Cooling

No Vacuum Applied Closes

Vacuum Supply to Power

Servo

Airflow Out of Upper and

Lower Outlets Door Open

1"
from 100% Lower Out-

let Position

Airflow Divided 1/3 Out

Defroster Outlets 2/3

Out Heater Outlets

Supplies Modulated Vacuum to Power Servo

Zero Voltage Applied to Transducer

Results in Maximum Vacuum Supply
10 Volts Applied to Transducer

Results in No Vacuum Supply

(Coolant Hot) Passes Vacuum When System is Calling For Outside Air

MAINTENANCE AND ADJUSTMENTS

EVAPORATOR CONTROL VALVE (POA)

(Chevrolet, Chevelle, Comoro, and Corvette

Four Season) (Chevrolet Comfortron)

The only check for proper POA valve operation is to

check the suction pressure at the valve as during a

performance test. The POA valve is an absolute valve

and will provide different gauge readings based on the

altitude where the readings are being taken. Correct

gauge reading at sea level is 29.5 psig. Gauge readings

will be one-half psi higher for each additional 1000 feet

of elevation. The following table lists gauge readings at

different altitudes. If a valve gives improper gauge

readings, it must be replaced since it is not repairable

or adjustable.

29.5

30.0

30.5

31.0

31.5

32.0

32.5

33.0

33.5

34.0

34.5
psig.

psig.

psig.

psig.

psig.

psig.

psig.

psig.

psig.

psig.

psig.
— Sea 1

— 1000

— 2000

— 3000

— 4000

— 5000

— 6000

— 7000

— 8000

— 9000
Level

ft.

ft.

ft.

ft.

ft.

ft.

ft.

ft.

ft.

— 10000 ft.
THERMOSTATIC SWITCH

(Universal and Chevy II All-Weather System)

Thermostatic switches used in Universal and All-

Weather systems differ only in the capillary tube sensing

unit.

The Chevy n All-Weather System thermostatic switch

has an air sensing capillary which is coiled and attached

to the front of the evaporator core with plastic plugs.

This type of unit is controlled by the temperature of the

air leaving the evaporator.

Universal systems make use of a thermostatic switch

with a fin sensing capillary or a self-supporting air sens-

ing capillary. This capillary controls the switch by

sensing the temperature of the metal fins or the air

leaving the fins.

Checking for Proper Operation

1.
Install the gauge set and set up the vehicle as

described under Performance Test.

2.
Movement of the temperature control knob should

result in a definite change in suction pressure and

cycling of the compressor clutch.

• If compressor continues to operate regardless of

the knob adjustment, it indicates that the points

CHEVROLET CHASSIS SERVICE MANUAL

HEATER AND AIR CONDITIONING 1A-42

EXTERNAL

EQUALIZER LINE

Fig. 54—Thermosratic Switch Adjustment

POORLY LOCATED POWER ELEMENT BULB

Normal Pressure.

Poor Cooling.

ENGINE IDLE COMPENSATOR

This additional aid to prevent stalling during prolonged

hot weather periods is included with all air conditioned

vehicles. The idle compensator is a thermostatically

controlled air bleed which supplies additional air to the

idle mixture. On V-8 engines, with factory installed air
Fig. 55—Expansion Valve

conditioning systems, the compensator is located within

the carburetor and is accessible when the engine air

cleaner is removed. On all other vehicles the compen-

sator is threaded into a manifold, fitting below the

carburetor. All compensators are factory set and are

non-adjustable. A malfunctioning unit should be replaced.

NOTE:
If engine idle is erratic, hold the idle

compensator valve closed with a pencil or

wooden dowel while adjusting the idle mixture

screw(s). Never attempt to bend the bimetal

strip or attempt any valve adjustment.

EVACUATING AND CHARGING PROCEDURES

1967 AIR CONDITIONING SYSTEM CAPACITIES

Four-Season Systems (Chevrolet and Chevelle)

Universal System (Chevrolet, Chevelle and Camaro)

Universal and All-Weather System (Chevy II)
Refrigerant Charge

3 lbs., 12 oz.

3 lbs.

2 lbs., 8 oz.
Oil Charge

11 ozs. 525 viscosity

11 ozs. 525 viscosity

11 ozs. 525 viscosity

PURGING THE SYSTEM

In replacing any of the air conditioning components the

system must be completely purged or drained of re-

frigerant. The purpose is to lower the pressure inside

the system so that a component part can be safely

removed.

1.
With engine stopped install high and low pressure

lines of gauge set to the proper high and low pres-

sure gauge fittings (see "Installing Gauge Set to

Check Operation").
2.
With plug removed from the centerline on the gauge

manifold, open high pressure gauge valve and dis-

charge the vapor slowly through the center

connection.

CAUTION: Do

compressor

refrigerant.
not open valves too much or

oil may be discharged with the

A rag wrapped around the end of

the center gauge line will prevent the splashing

of oil in the event of accidental rapid discharge.

CHEVROLET CHASSIS SERVICE MANUAL