Engine wiring CHEVROLET CAMARO 1967 1.G Chassis Workshop Manual

HEATER AND AIR CONDITIONING 1A-5

them in their proper location. (See Figure 8)

12.
Refill radiator.

Defroster Duct

Figure 9 illustrates the defroster duct installation

on Chevrolet, Chevelle and Camaro vehicles.

Bowden Cobles

Bowden cable attachment should be made in the fol-

lowing manner:

1.
With the cables attached to the control assembly

and levers, move the levers to their fully left or

closed position.

2.
Attach cable wires to the heater valve levers and

tighten cable attaching bracket screws.

3.
Check for proper cable operation and readjust as

necessary.

Control Panel

Control panel installation is shown in Figures 10, 11,

and 12.

Fan Switch

Replacement

1.
Remove control assembly-to-instrument panel re-

inforcement attaching screws and push the control

assembly toward the front of the vehicle and down.

2.
Remove the two switch attaching screws and the

electrical connector.

3.
Replace switch, screws, and electrical connector.

4.
Place control assembly into instrument panel and

replace attaching screws.

Resistor

The resistor assembly is attached to the heater dis-

tributor assembly. It should "be replaced if low or

medium blower speed is inoperative. Remove the glove

box for access to the unit.
HEATER HOUSING

LOWER RIGHT HAND

RETAINER NUT

Fig.
6—Air Distributor Duct (Camaro)
Fig.
7—Access to Blower and Housing (Chevelle)

CHEVY II

Heater Assembly

Removal (Fig. 13)

1.
Drain radiator.

2.
From within engine compartment;

a. Remove heater hoses from heater inlet and outlet

connections.

b.
Remove three nuts around blower motor attaching

heater assembly to dash panel.

3.
From within vehicle:

a. Remove glove box and glove box door.

b.
Remove screw attaching distributor bracket to

dash.

c. Remove the screw attaching case bracket to the

adapter assembly bracket.

d. Carefully detach heater assembly from dash panel

and adapter assembly and lower it toward floor of

vehicle.

e. Disconnect all bowden cable connections, the

wiring connector and the defroster hoses.

4.
Remove the heater assembly from the vehicle.

Core Replacement

1.
'With the heater assembly removed from the vehicle,

remove the screws attaching the core cover to the

heater assembly.

2.
Remove the core mounting screws and remove the

core from the assembly.

3.
Replace with a new core and replace the core cover.

Installation

1.
Be sure the adapter seal and blower motor seal are

in place and set into place beneath the instrument

panel.

CHEVROLET CHASSIS SERVICE MANUAL

HEATER AND AIR CONDITIONING 1A-10

PLATE RETAINERS

CORE BRACKET SCREWS

Fig.
18—Corvette Heater Core Removal

7. Place a protective covering (waterproof if possible)

over the carpeting under the heater.

8. Remove the two bowden cables from the instrument

panel and disconnect the wiring connectors from the

blower switch and from the resistor.

9. Carefully work the heater assembly out from beneath

the dash.

Core Removal

1.
Remove the heater assembly as described above.
2.
Remove the sheet metal nuts which retain the core

mounting plate to the core housing.

3.
Remove the screws attaching the core brackets to

the core mounting plate and separate the core and

plate. .

Installation

1.
Assemble the core to plate with non-hardening

sealer. Attach the core mounting screws.

2.
Attach the core and plate assembly to the case with

the two sheet metal nuts. The assembly is ready for

installation as described below.

Heater Assembly Installation

1.
Carefully position the heater assembly in place on

inner surface of dash panel, then install the blower

and air inlet assembly on heater studs extending

through to the engine side of the panel. Attach the

seven stud nuts.

2.
Install electrical connectors to the blower switch and

resistor and reinstall the bowden cables to the

instrument panel.

3.
Replace the blower electrical connectors.

4.
Replace the heater hoses. (See Figure 20)

5. Replace the battery and the radiator supply tank.

6. Refill the radiator and check for leakage.

7. Check heater operation and make control adjustments

as necessary.

8. Replace the console panels and the glove

compartment.

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-34

a. Blower comes on High speed.

b.
Cold air comes from A/C outlets.

3.
Rotate Temperature Dial to 85°F.

a. Blower speed will decrease to Low speed then

increase to Medium or High.

b.
Air temperature changes from Cold to Hot and

comes out heater outlet.

4.
Move control lever to LOW Front, with Temperature

Dial at 85°F. Blower operates at Low and Medium

speeds.

5.
Move control lever to Rear, set Temperature Dial

at 65°F.

a. Blower goes to High speed and maintains high

air flow.

b.
All air comes from A/C outlets.

6. Move control lever to DE-FOG.

a. Blower is on Medium or High Speeds.

b.
Air comes from Defroster and Heater Outlets.

7.
Move control lever to DE-ICE.

a. Blower is on High Speed.

b.
Air temperature goes to warm and most of air

comes from defroster nozzle, with small amount

of air coming from heater outlet.

c. Outside air door is open - (door valve is closed

to car body).

8. Move control lever to REAR (dial at 65°). Outside

air door moves outboard. (Door valve is open to

car body).

CHEVROLET COMFORTRON TESTER

The J-22368 Automatic Temperature Control Tester

when in AUTOMATIC position, may be used to perform
Comfortron system checks without disturbing normal car

operation.

Under MANUAL control tester allows the operator to

set and hold a predetermined blower speed
and.
temper-

ature. The tester can also be used to measure external

system voltages by using the probe.

To Install the Tester

1.
Remove the three-terminal male connector from the

Amplifier on the Comfortron control head.

2.
Plug this connector into the three terminal female

connector (with yellow wire)
on
the Tester.

3.
Plug the remaining three-terminal male connector

on the Tester into the Amplifier on the control head.

4.
Attach the black ground lead to any good ground

point available in the car.

5.
Remove the large vacuum hose from Transducer and

connect it to the Tester vacuum hose nipple.

6. Connect the Tester vacuum hose (short hose) to the

Transducer.

Quick Test Procedure

With the J-22368 Tester installed as outlined above,

the following quick checks may be made to pinpoint

the cause of system malfunctions. This quick check

procedure is reproduced on the "swing out" plastic

instruction card attached to the back of the Tester.

Before performing the checking procedure, start the

engine and allow to run on fast idle until operating

temperature is reached. Then set the dash control lever

to HI-FRONT position and the dash control Temperature

Dial to 75° and proceed with the following steps:

Step

1

2

3

4

5A

5B
Tester Settings

Rocker

Switch

Manual

Manual.

Manual

Manual

Manual

Auto-

matic
Voltage

Source

Sensor

Amplifier

or

Control

Cal.

Trans-

ducer

Amplifier

or

Control

Cal.

Amplifier

or

Control

Cal.
Manual

Control

150

150

a. Max.

Heat*

b.
Max.

Cold*

a. Max.

Cold*

b.
Max.

Heat*

Set to

150 for

Comfortron

System

Same as 5A.

Allow 5 min.

for system

to stabilize

with doors

and windows

closed.
Tester Should

Indicate:

Battery Voltage

Battery Voltage

0-4 Volts

8 Volts Min.

8 Volts Min.

0-3 in. Vac.

0-4 Volts

9 in. Min. Vac.

6.5 Volts

5.5 to 7.5 Volts
To Correct Abnormal Indication:

Check fuse and wiring.

Check for open in sensor circuit.

See Service Manual:

Malfunctioning Amplifier or Temperature

Dial.

Check for open or bad ground in trans-

ducer circuit or replace transducer.

Rotate car temperature dial until meter

reads 6.5 volts. Car temperature should

'•- indicate 75°. If not, see temperature

calibration which follows.

After 5 minutes of operation check for

defective sensor.

•This setting should result in HIGH blower speed. Refer to shop manual for further operational checks.

CHEVROLET CHASSIS SERVICE MANUAL

HEATER AND AIR CONDITIONING 1A-36

(These tests should be performed with the engine at operating temperature.)

SYSTEM CHECKS

Control

Head

Setting

High

Front

Lo

Front

Lo

Front

Hi

Front

Hi

Front
Tester Settings

Function

Manual

Manual

Manual

Manual

De-ice

65° on

Temp.

Dial

Hi

Front

Hi

Front

Hi

Front
Auto-

Matic

1 1

Auto-

matic

Manual

Manual
Manual

Control

Max.

Heat

Rotate

from

Max.

Heat to

Max.

Cold

150

Max.

Cold

Max.

Cold

Max.

Cold

Max.

Heat

Max.

Heat

Max.

Cold
Voltage

Trans-

ducer

Trans-

ducer

Ampli-

fier

Trans-

ducer

Probe

Probe

Trans-

ducer

Trans.
Tester Should

Indicate:

High Blower

Maximum Heat

Reduced Blower

Speed

Complete series of

blower changes from

Hi to Lo to Hi

again.

AMPLIFIE:

Remove conn, from c

Voltage reading she

Short this lead to grc

Voltage reading she

No voltage change in<

COMPRESSOR C

Cooling System

Operation

DE-ICE i

Assuming rest of

system is operating

normally: Max. Heat

1
to windshield.

SENSOR STR

•—

TRAtfSDtfC

0-3"
Vac. Reading

8 Volts Min.

9"
Min.
Vac.
Reading

0-4 Voltage Reading
If not, check

the following:

Fuse in Slock

In Line Fuse

High Blower

Delay Relay

Duct Delay

Thermistor

High Blower

Delay Sensor

Power Servo

Blower Switch

Resistor

Blower Motor

Wiring Harness

Blower Switch

Master Delay

Thermistor

Master Delay

Relay

Resistor

Power Servo

Blower Motor

CHECK

Resistor

I CHECK
Electrical Diagram

Probe Points:

1-2

8-9

10-21

20

18

19

*
9-46

-r

^2-3
15

16

Checked during

above procedure.

(This is a com-

plete step-by-step

high blower circuit

check which also

checks wiring

harness.)

4

5

6

L2-13

L4

""§2-15

39-46

1
16 1

14

22-40-42-44-15

.ontrol head temperature dial.

>uld be 9 volts minimum,

jund.

>uld be 0 volts,

iicates malfunctioning of amplifier.

JUTCJH CHUCK

Compressor Clutch

(Grille Temp, must

be above 40°.)

IRCUIT

Blower Switch

Master Delay

Relay

Transd

NGCl
ucer

Sensor String

2R CHECK

Transducer voltage

&t Max. Cold

position)

Transducer Ground

Hi Blower Outside

air (air door closed

to car body). Hot air

from heater outlets.

Hi Blower Recirc.

Air (air door open

to car body) cold air

from A/C outlets.
24-25-26-27-28
Voltmete

should re
ad

Battery Voltage

Battery Voltage

Battery Voltage

. Vtinimum
6
volts

Battery Voltage

Minimum
6
volts

Battery Vo]

Batterv Vo]
Ltage

Ltage

Battery Voltage

Batterv Voltage

3a

Bai
:terv Vo

tterv Vo
tage

tage

Minimum
6
volts

Batterv Voltage

Minimum
6
volts

Battery Voltage

Minimum
8
volts

Minimum 8 volts

Minimum 8 volts

Batterv Voltage

Minimum 8 volts

1 III • II »ll. —..• —•— . !!•• 1

Battery Voltage

3-23

20-10-21

38

29-30-31-32-33-

34-35-36

37-38

Defective Power Servo; Leak in Vacuum

System; Temp.; Door Link Disconnected

or Jammed; Defective Vacuum Relay

Valve

Defective Mode Door Diaphragm
Batterv Voltage

Battery Voltage

Zero Voltage

Battery Voltage

Battery Voltage

CHEVROLET CHASSIS SERVICE MANUAL

HEATER AND AIR CONDITIONING 1A-53

Fig.
70—Wiring and Vacuum Lines—Four-Season (Camaro)

Installation

1.
Connect the expansion valve to the refrigerant pipes.

Attach the capillary bulb to the evaporator.

2.
Attach the evaporator to the- case. Attach the inlet

and outlet pipes clamps.

3.
Assemble the case halves. Insert the capillary tube

from the thermostatic switch between the fins as

shown in Figure . Attach the cover plate to the

case.

4.
Mount the unit to the dash and connect the refrigerant

lines.

5.
Evacuate and charge the system. If a new evaporator

was installed, add three fluid ounces of refrigerant

oil to the system before charging.

6. Test system operation.

Chevy II All-Weather System

Removal

Under
the Hood

1.
Purge the refrigerant from the system.

2.
Remove the refrigerant hoses from the evaporator

inlet and outlet connections extending through the

special grommet in the dash panel and into the

engine compartment.

3.
Remove the screw, nut, spacer bracket and grommet

from the outlet connection pipes.
Within the Car

4.
Remove the glove box, ash tray and ash tray

retainer.

5.
Reach through the glove box door to disconnect the

air conditioning "on" door bowden cable (fig. 75).

6. Remove the two shield attaching screws and shield

(A, fig. 76) which covers the lower right evaporator

bracket-to-blower bracket attaching screw (B, fig.

76),
then remove this screw.

7.
Behind the lower left side of ihe evaporator, remove

the evaporator bracket-to-heater distributor bracket

attaching screw (C, fig. 76).

8. Reaching through the glove box door and ash tray

openings, remove the two nuts and washers (D,

fig.
76) attaching the evaporator assembly studs to

the lower instrument panel flange and reinforcement.

9. Disconnect the drain hoses and carefully pull the

evaporator unit toward the rear of the vehicle.

10.
Disconnect wiring connectors (see fig. 77) as nec-

essary and remove the evaporator unit from the

vehicle.

Gore and/or Expansion Valve Replacement

A defective unit must be replaced since repairs should

never be made on the evaporator core. Before replacing

the core, however, check to be sure that any leaks pres-

sent are not located at the hose connections or expansion

valve connections. The following procedure assumes that

the evaporator unit has been removed from the vehicle

as outlined above.

CHEVROLET CHASSIS SERVICE MANUAL

HEATER AND AIR CONDITIONING 1A-56

BLACK & RED

IGNITION—-y^****

SWITCH -"A

/<J 7

BLOWER LEAD—^^^

RESISTOR—-" \^<

ASM.
f'

i
'fu^^^^A^^^^^r"G^OUH£>
WIRE

^^
k4

^EVAPORATOR HARNESS

' EVAPORATOR & BLOWER ASM.

Fig.
73—Underdash Wiring—Universal System (Typical)

evaporator outlet pipes. Locate the bracket about

1/2" from the dash panel.

12.
Replace the inlet and outlet hoses and hose clamp

connections.

13.
Evacuate and charge the system. Add three fluid oz.

refrigerent oil after installing a new core.

14.
Check system performance.

Corvette

Replacement (Fig. 78)

1.
Purge the system of refrigerant.

2.
Drain the engine radiator. Then remove the radiator

supply tank from its brackets, the heater water

valve and vacuum line from the firewall, and the

heater hoses from the core pipes. Carefully fold the

hoses,
valve and tank away from the evaporator

case.

3.
Remove the right hand hood lock support.
SCREW DRIVER

(NARROW BLADE) T£

GROOVE

A. Insert screw driver in

tang toward terminal

B. Pry tang back out to

when reinstalled into
RMINAL

\ CONNECTOR

TANG

groove & press

to release.

insure locking

connector.

Fig.
74—Terminal Removal—Universal System

4.
Disconnect the expansion valve equalizer line con-

nection and the evaporator oil bleed line from the

POA.

5.
Disconnect the evaporator outlet to POA inlet

connector.

6. Remove the POA bracket to evaporator case attach-

ing bolts. Then carefully move the valve and its

outlet hose away from the evaporator case.

Fig.
75-Cable Removal-All Weather

CHEVROLET CHASSIS SERVICE MANUAL

HEATER AND AIR CONDITIONING 1A-64

Fig.
90—Evaporator Wiring (Corvette)

AIR INLET VALVE

Four-Season System

Chevrolet

Figure 88 illustrates the vacuum valve which controls

the air inlet operation of the Four-Season System.

A vacuum tank and check valve is used to assure that

the air door will not change its position due to variations

in engine vacuum.

Camqro

Figure 89 illustrates the outside air inlet door assem-

bly, and the door in the kick pad which admits reeir-

culated air to the system.
BLOWER AND EVAPORATOR ASSEMBLY

(Corvette)

Replacement

1.
Remove the evaporator core as outlined under

"Evaporator Core Replacement".

2.
Remove the blower motor as outlined under "Blower

Motor Replacement".

3.
Remove the heater and air conditioning distributor

as outlined under "Air Distributor Duct Removal".

4.
Remove the remaining nuts attaching the blower

and evaporator assembly and the cover assembly

to the studs on the -firewall.

5. Replace the components removed by reversing the

removal, procedure.

AIR DISTRIBUTOR ASSEMBLY

AND OUTLET DUCTS

Four Season System

Chevrolet and Chevelle

Figures 92 through .95 illustrate the air distributor and

outlet ducts as used in the Chevrolet, Chevelle, Camaro,

and Corvette.

Corvette

Right Outlet Duct

Removal

1.
Remove the clamp screw at the inner end of the

outlet duct and loosen the clamp.

2.
Remove the screw and lock washer attaching the

duct outer mounting tab to the body hinge pillar

brace.

3.
Pull the duct and clamp down and away from the

distributor assembly. Disconnect the courtesy light.

4.
The duct extension assembly may now be removed

if desired as well as the deflector assembly. See

Figure 95.

AIR COND.

PULL
AIR PULL- DEFROSTER

FAN PULL HOT PULL

Fig.
91—Corvette Four-Season Controls

CHEVROLET CHASSIS SERVICE MANUAL

HEATER AND AIR CONDITIONING 1A-67

Fig.
94—Camaro Four-Season Ducts

Heater and Air Distributor Assembly

Removal

rfooo

1.
Disconnect battery ground cable.

2.
Drain radiator (do not purge refrigerant system).

3.
Disconnect all connectors attached to the Comfortron

wiring harness which are on the engine side of the

firewall. Push the wiring harness grommet through

the firewall to the rear.

4.
Disconnect the four vacuum hoses coming from the

underdash through the large firewall grommet. Push

the hose grommet through the firewall to the rear.

5.
Remove the nuts from the heater and air distributor

case studs which project through the firewall from

the dash side.

6. Disconnect the heater hoses from the core tubes.

Under Dash

1.
Remove glove box assembly.

2.
Remove the dash center face plate, ash tray assem-

bly, and any radio and/or tape equipment.

3.
Remove the Comfortron control assembly mounting

screws and lower the control unit.
4.
Remove the vacuum line from the kick pad valve

diaphragm.

5.
Disconnect all harness connectors between the Com-

fortron harness and the rest of the dash wiring.

6. Remove the air distributor duct which supplies the

dash outlets.

7.
Remove the screws attaching the heater and air

distributor to the firewall.

8. Pull the assembly rearward then down to remove

from the dash. Pull the Comfortron wiring harness

and vacuum hose assembly through the firewall.

Installation

1.
Place the entire case assembly with wiring, vacuum

hoses,
and control assembly into the car on the floor.

2.
Pass the underhood wiring harness and vacuum hose

harness as far as possible through the appropriate

firewall holes.

3.
Lift the assembly up into position and pass the case

studs through the firewall mounting holes. Attach

the case to the firewall with the mounting screws.

4.
Mount the dash outlet air distributor duct to the face

of the case.

CHEVROLET CHASSIS SERVICE MANUAL

HEATER AND AIR CONDITIONING 1A-68

Fig.
95—Corvette Four-Season Ducts

5. Connect the various Comfortron harness connectors

to the dash wiring and connect the vacuum hose to

the kick pad valve diaphragm. Push the vacuum hose

harness and wiring harness through the firewall to

the proper location and install their respective

grommets.

6. Raise the control unit into place and install the

mounting screws. Check that all connections are

complete.

7. Replace any radio and/or tape equipment, the ash

tray assembly, and face plate.

8. Replace the glove box assembly.

9. Connect the heater hoses to the core tubes, and

attach the nuts to the case studs through the firewall.

10.
Reconnect the four vacuum hoses as follows: Purple

to the cylinder on the thermo-vacuum valve, yellow

tracer to the body of the thermo-vacuum valve, red

tracer to the vacuum source "Tee" connection, and

white tracer to the vacuum tank inlet.

11.
Connect the wiring harness to the underhood air

conditioning components.

12.
Refill cooling system, connect battery ground cable

and check system performance.

Vacuum Tank

The vacuum tank is mounted on the firewall as shown

in Figure 97. Notice that the two vacuum lines are

clamped to the vacuum tank ports. *

Thermal Vacuum Valve

This heat operated vacuum valve is located in the

heater core input line. Figure 98 illustrates valve instal-

lation with clamps attaching the water hoses as well as

the vacuum hoses in place.
Resistor Assembly

Figure 99 illustrates the location and installation of

the blower speed resistor assembly.

Relays

Two relays are used in the system, both mounted on the

evaporator case as shown in Figure 100. The mounting

bracket forms a common ground for the relays and as a

plug for the hole in the evaporator housing used in the

Four Season system for resistor installation.

Sensors (Thermistors)

Ambient Switch and Sensor

This combination unit, which engages the compressor

clutch at about 40°F and also senses outside air tem-

perature and sun load, is mounted to the firewall within

the engine compartment with its long neck extending

deep into the cowl vent plenum chamber. Figure 98 il-

lustrates this installation,

In-Car Sensor

This sensor is located beneath the lip of the instru-

ment panel overhand just to the right of the driver as

shown in Figure 101.

Removal

1.
Remove glove box assembly.

2.
Disconnect sensor wires connector at harness.

3.
Remove sensor mounting screws, remove sensor

and pull wires and connector through hole in dash.

Installation

1.
Insert connector and

through the dash hole.
wires of replacement sensor

CHEVROLET CHASSIS SERVICE MANUAL