1967 CHEVROLET CAMARO service

HEATER AND AIR CONDITIONING 1A-12

I. 20—Heater Hoses-Corvette

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-14

Fig.
21—Four-Season System Components (Chevrolet)

Fig.
22—Four-Season System Components (Chevelle)

CHEVROLET CHASSIS SERVICE MANUAL

HEATER AND AIR CONDITIONING 1A-15

Fig.
23—Four-Season System Components (Camaro)

EVAPORATOR

CORE

DEFROSTER

OUTLET DEFROSTER DOOR

V

HEATER

OUTLET

COOLED AIR OUTLETS

Fig.
24—Airflow—Four-Season (Chevrolet, Camaro) Comfortron (Chevrolet)

CHEVROLET CHASSIS SERVICE MANUAL

HEATER AND AIR CONDITIONING 1A-16

EVAPORATOR

CORE

\

BLOWER AND AIR I

INLET ASSEMBLY •

AIR

DOOR

OUTSIDE AIR FROM COWL VENT

DEFROSTER

DUCT

DEFROSTER

DOOR

COOLED AIR

OUTLETS

Fig.
25—Airflow—Four-Season (Cheyelie)

will be hot at all times. When, during cooling operations,

the air is cooled by the evaporator to below comfort

level, it is then warmed by the heater to the desired

temperature; during "heating only" operations the evap-

orator will not be in operation and ambient air will be

warmed to the desired level in the same manner. The

side dash outlets may be rotated to provide either soft,

diffused airflow or spot cooling. Rotate half way to shut

off airflow. The barrel type outlet in the center of the

dash will direct air up or down or, if desired, shut it off.

Controls

Four-Season System (Chevrolet, Camaro)

Full control of the Four-Season System is obtained

through the use of a single control panel (fig. 26). The

control knobs make use of bowden cables to activate the
various doors and switches necessary for system opera-

tion.
Therefore, control adjustment is a matter of

properly setting these bowden cables. The following

paragraphs explain each control.

Temperature Lever

The TEMPERATURE lever controls temperature door

position, compressor operation, and air selector door

position. When the lever is in the OFF position, the sys-

tem is totally inoperative; airflow is shut off, the fan

switch will not operate the blower, and the compressor

is off. In the VENT position, the air selector door is in

the "outside air" position and the blower is powered at

low speed. At any lever position other than OFF, the

blower will be powered at low, however, blower speed

may be increased by moving the FAN switch. When the

Fig.
26—Chevrolet Four-Season Controls
Fig.
27—CheveNe Four-Season Controls

CHEVROLET CHASSIS SERVICE MANUAL

HEATER AND AIR CONDITIONING 1A-17

i

c

Fig.
28—Comfortron Underdash Components

lever is above and slightly left of the COLD position, the

compressor is on, the air selector door is in the re-

circulation position, the temperature door is in the fully

cold position, and the blower is operating. Moving the

lever slightly to the right of COLD moves the air selector

door to the full outside air position while temperature

door, compressor, and blower functions remain the same

as in the "recirculating - COLD" system operation.

Moving the TEMPERATURE lever further to the right

moves the temperature door which channels some air

through the heater core. At a point about midway between

COLD and HOT, the compressor clutch switch opens and

the system is operating as a heater only with untreated

outside air (passing through the inoperative evaporator

core) mixing with heated outside air. With the lever in

the HOT position, all air (outside air) passes through the

heater core for full heat output.

Outlets and Defroster Levers

While the TEMPERATURE lever is in any operating

position, the OUTLETS and DEFROSTER levers may be

operated as desired. The OUTLETS lever directs the air

to either the heater outlet, both heater and dash outlets,

or to the dash outlets only. The DEFROSTER lever

directs air (which is flowing to the heater outlet) up to

the defroster outlets. With the DEFROSTER lever, in

the OFF position, a fixed bleed permits a small quantity
of air to flow to the defroster outlets while the major

volume of air flows from the heater floor distributor.

In the DEFROST position, airflow is split between the

heater and defroster outlets. In the DE ICE position, all

air is diverted to the defroster outlets. Since the air

must be in the heater duct in order to be directed by the

defroster door, the OUTLETS lever must be in LOWER

position which causes air to flow out the lower outlets,

if the OUTLETS lever is in the UPPER position, de-

froster door movement will have no effect on the system.

Fan Switch

The fan switch controls the operation of the three

speed blower motor except when the TEMPERATURE

lever is in the OFF position.

Four-Season System (Chevelle)

Full control of the Chevelle Four-Season is obtained

through the use of a single control panel (fig. 27) much

the same as that previously described for the Chevrolet

Four Season System. The Chevelle control differs in

operation only in that AIR and TEMPERATURE are sep-

arate controls rather than a combination control as in the

Chevrolet control panel. Except for this difference,

operation of the levers is similar to the Chevrolet

controls.

CHEVROLET CHASSIS SERVICE MANUAL

HEATER AND AIR CONDITIONING 1A-18

HIGH BLOWER

i DELAY RELAY

AMBIENT-SUN

SENSOR AND

COMPRESSOR SWITCH

Fig. 29—Comfortron Engine Compartment Components

COMFORTRON SYSTEM

The Chevrolet Comfortron Air Conditioning System is

basically the same as the Chevrolet Four-Season system

but with the additional feature of completely automatic

control. See Figures 28, 29 and 30 for views of the

Comfortron system. To the customer, the most notice-

able difference between the two systems, will be in the

control panel. In place of the three-lever/one-switch

panel of the Four-Season system, the Comfortron has a

single control lever plus a temperature dial similar to

that found in a home thermostat. After the dial is set to

the desired temperature indication and the lever is moved

to place the system in operation, the Comfortron will

automatically control the heating and air conditioning

functions to maintain the selected interior temperature

regardless of changes in outside air temperatures.

Most Comfortron parts are located in the passenger

compartment, (fig. 28)

Jn-Car Sensor

The function of the in-car sensor is to determine the

temperature of the interior of the automobile. It is

located beneath the overhang of the instrument panel.

Feedback Potentiometer

The feedback potentiometer indicates to the amplifier

system the position of the temperature door.
Control Head

A thumb wheel is provided to select the desired in-car

temperature. A control lever performs the following

functions:

1.
Operates a switch that allows the customer to select

the type of blower program desired.

2.
Operates the control head vacuum switch except

when the TEMPERATURE lever is in the OFF

position, thus programming the vacuum system.

3.
Operates the defroster through the control head

vacuum switch. The defroster door is partially

opened in the "DE FOG" position, and fully open in

the "DE ICE" position.

A two transistor amplifier is located on the bottom

side of the control head. It receives information from

the sensors, and in turn operates the transducer.

Fig. 30—Comfortron Control

CHEVROLET CHASSIS SERVICE MANUAL

HEATER AND AIR CONDITIONING 1A-19

Transducer

The transducer will produce a vacuum output that is

completely adjustable by varying the input voltage which

is provided by the amplifier. An increase in the applied

voltage results in a reduced vacuum output.

Power Servo

The power servo receives a vacuum signal from the

transducer, and it is capable of assuming any position

that is called for by the sensors, amplifier, and trans-

ducer. The power servo performs the following functions:

1.
Positions the temperature mix door via the tern-

perature door link. The position of this door~"de-

termihes the portions of hot and cold air being

blended and discharged into the car.

2.
Operates the power servo vacuum valve which de-

termines the air flow paths for heating and air

conditioning.

3.
Contains a printed circuit board which controls the

blower speed. The power servo position determines

the blower speed, but the control lever switch can

override the blower program depending upon the

customer's preference.

4.
Contains the "Hi" blower delay thermistor and the

"master delay thermistor".

Outside Air Diaphragm

When there is no vacuum applied to the hose, the out-

side air door is closed under spring tension. With the

door closed, air is taken from the inside of the auto-

mobile and re-circulated. Applying vacuum to the dia-

phragm opens the door for outside air.

Mode Door Diaphragm

Located behind the duct work, the mode door diaphragm

directs the air flow out either the air conditioning outlets,

the heater floor outlet, or both the heater and air con-

ditioning outlets. This is a push-pull type diaphragm

actuated by vacuum through two hoses and controlled by

the power servo vacuum switch.

Defroster Door

The defroster door is in the defog position until vacuum

is applied to the actuator to obtain either full heat or full

de-ice position.

High Blower Delay Thermistor

The high blower delay thermistor is located on the

power servo housing under the power servo vacuum valve

and printed circuit board assemblies. The function of the

thermistor is to operate the blower at a reduced speed

when the control is in the HI FRONT position until the

residual cold air is discharged from the duct work. This

function occurs when the blower first comes "on" in cold

weather.

Vacuum Tank

During heavy acceleration, the vacuum supply from
the carburetor drops. The vacuum tank, using a^ check

valve, stores vacuum so that under these conditions

vacuum will be available for the Comfortron.

Thermal Vacuum Valve (Hot Water Vacuum Switch)

When engine coolant temperature reaches 75°F, the

valve opens and supplies vacuum to the outside air door

if the system is calling for outside air.

Master Delay Thermister

This thermistor delays the initial operation of the

blower when the system is in the heat mode. In cold

weather this allows outside ram air to flow through the

system thereby purging the cold air in the ducts gradually

until the coolant reaches about 105°F. Then, the termis-

tor passes enough current to energize the master delay

relay which powers the blower at about nine volts.

Vacuum Relay Valve

This relay valve will shut off transducer vacuum to the

power servo whenever the vacuum from the engine intake

manifold falls below the vacuum in the power servo

supply line (engine stopped or operating at low manifold

vacuum). This causes the power servo to be held in

position when the vacuum supply falls too low to maintain

servo control.

Vacuum Bleeder

A vacuum bleeder insures that the outside air door will

close (diaphragm will bleed down) after the system has

been shut down. This prevents outside air from entering

when starting the system on a cold day before the engine

coolant temperature reaches 75°F.

Sun—Ambient Sensor

The sun-ambient sensor measures the temperature of

the air entering the air intake grille in front of the wind-

shield. The sensor is exposed to sun light so that it can

lower the in-car temperature slightly when the sun

is shining.

Ambient Switch

The ambient switch operates the air conditioning com-

pressor clutch. When the outside temperature is above

40° F. the switch will be closed and the compressor will

be running. This switch is included as| part of the sun-

ambient sensor assembly, but operates independently.

Resistor Assembly

The blower resistors are located in the evaporator

housing. The printed circuit board switch in the power

servo determines which of the resistors is being used,

and as in conventional systems, the resistors control the

blower speed.

System Operation

When starting the Comfortron System in cold weather,

the following sequence of events occurs:

1.
Initially the system is inoperative. In LO FRONT

position the master delay thermistor is warming

(self-heating because current is flowing through it)

CHEVROLET CHASSIS SERVICE MANUAL