sensor CHEVROLET CAMARO 1967 1.G Chassis Workshop 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

HEATER AND AIR CONDITIONING 1A-20

and its resistance is decreasing. In the HI FRONT

position, two thermistors (the master delay and high

blower delay thermistors) are warming. The air

door is in recirculation position until the engine

coolant reaches 75 degrees.

2.
The coolant reaches then 75 degrees and the thermal

vacuum valve opens applying vacuum to the air door

to admit outside air (unless the temperature dial is

set for cooling). Ram air will flow through the sys-

tem when the car is moving.

3.
Next, the master delay thermistor attains the tem-

perature at which it will pass sufficient current to

close the circuit through the master delay relay.

The relay circuit powers the blower motor at 9 volts.

4.
If the control is in the HI FRONT position, the high

blower delay thermistor will close the circuit

through the high blower relay which supplies full

available voltage to the blower motor. This function

occurs after the master delay thermistor has taken

effect because the high blower delay thermistor

uses the master delay type thermistor with a 10 ohm

1/4 watt resistor connected in
.
series. The nigh

blower delay thermistor must then warm to a higher

temperature than the master delay thermistor before

its resistance (plus that of the 10 ohm resistor)

drops enough to actuate the high blower relay.

5. If the controls are set for DE ICE, full outside air

and full voltage to the blower motor are effective

immediately regardless of temperatures or elapsed

times o

In accomplishing automatic control, the system follows

three steps to transform an electronic signal into me-

chanical energy through which the control is achieved.

Electronic Circuit

Two temperature sensors (Thermistors), and the duct

potentiometer connected in series, are located so as to

sense the temperature of the outside air, inside air and

system output air. The resistance of each sensor will

vary according to its temperature. The control head

temperature dial varies in resistance as it is adjusted by

the operator to suit his comfort requirements. The

resistance of the temperature dial control is applied

directly to the amplifier and is not in series with the

sensors and duct potentiometer. Thus temperature dif-

ferences in the sensor string plus the requirements fed

into the system by the operator cause changes in total

circuit resistance which allow a varying voltage flow

through the circuit.

Changing the Electronic Signal to Electrical Voltage

This minute voltage flow from the sensor string -

temperature dial circuit - is fed into the amplifier where

it is transformed into a usable amplifier output voltage,

the strength of which is determined by the strength of the

original amplifier input signal. This voltage is then

supplied to the transducer.

Changing the Electrical Voltage to a Vacuum Signal

Amplifier output voltage, varying according to tem-

perature requirements, is converted by the Transducer

into a modulator transducer output vacuum. This modu-

lated vacuum is applied to the Power Servo.

Changing the Vacuum Signal to Mechanical Energy

The Power Servo, controlled by the modulated Trans-
ducer output vacuum, operates the vacuum electrical and

mechanical components of the system as required to

provide automatic control of system operation.

Other major system components are mounted con-

ventionally in the engine compartment. Underhood com-

ponents and system airflow remain much the same as in

the Four-Season system except for the addition of the

automatic control provisions. The system operates on

100%
outside air, a mixture of outside and inside air, or

100%
recirculated air depending on the demands of the

system. The diaphragm operated .air selector door will

modulate outside air to the system during maximum air

conditioning requirements when the control unit is in

"Hi Front" position. Control of the blower is also com-

pletely automatic and dependent upon system demands.

Controls

The Comfortron controls the Chevrolet air conditioner

and heater in such a precise manner that the automobile

temperature remains relatively constant under all driving

conditions. By adjusting the thumb wheel on the Control

Head to any temperature desired between 65° and 85° F.

(See Figure 27) the automatic system will adjust the in-

car temperature even though the outside weather condi-

tions may vary considerably. The system will provide

maximum capacity for heating or cooling until the in-car

temperature reaches the pre-set Control Head Tempera-

ture. Where cooling is required, the system will start

immediately upon being turned "ON". During marginal

ambient temperatures the system will not always start

at the highest blower speeds of the control setting.

Therefore, occasionally the system can't be heard

starting*

Five over-riding functions are available so that special

conditions can be handled. Each Control Head function

will be discussed in detail below:

"Off" Position

In the "Off" position, the blower is turned off and the

outside air door is closed. No outside air should enter

the automobile.

"Lo Front" Position

The blower has five low to moderate speeds; Hi, M3,

M2,
M1 and Lo. The blower voltage will shift as directed

by the automatic controls. The "Lo Front" position

provides a quieter mode of automatic operation due to

reduction of blower noise.

"Hi Front" Position

The "Hi Front" position provides five high blower

speeds as called for by the automatic controls: The use

of the "Hi" blower speed results in a rapid cool down in

hot weather and rapid heating during cold weather. As

the in-car temperature approaches the temperature set-

ting on the Comfortron Control Head, the blower speed

will change, provided mild outside temperatures are

experienced. During very hot or cold weather, the blower

will reduce its speed only to the point where it is still

capable of maintaining the correct inrcar temperature.

"Rear" Position

The "Rear" position provides five high blower speeds.

The automatic controls select these speeds and blend the

discharge air to the proper temperature. By the use of

high blower speeds, increased airflow is obtained for

better rear seat passenger comfort.

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-35

Checking Condition of Thermistors (Sensors)

1.
Install Tester J-22368 as previously described.

2.
Start the engine and run at fast idle. Move the

Comfortron control lever to HI-FRONT.

•Set Rocker switch to MANUAL.

•Set Manual Control Knob to 150 ohms on scale.

3.
Set the Tester Voltage switch to AMPLIFIER.

4.
Rotate Comfortron Temperature dial until the Tester

voltmeter reads 6.5 volts. The dial should read 75°,

Adjust dial if necessary.

5.
After car has run (windows and doors closed) for at

least 10 minutes, switch Rocker switch to AUTO-

MATIC. Voltage reading should remain at 6.5. A

change in the voltage indicates a bad sensor.

6. If a bad sensor is indicated in Step 5, check each

sensor, disconnected from the system, with an ohm-

meter. Approximate resistance of each sensor at

75°F.
should be as follows:

In-car Sensor — 50-75 ohms

Ambient Sensor --,55 ohms or less

Duct Delay Sensor -.- 25-75 ohms

Feedback

Potentiometer —

Master Delay

Thermistor -- 70 ohms

High Blower Delay

Thermistor -- 80 ohms including

10 ohm resistor

(Located in Power Servo casting)
VACUUM
ELECTRICAL LEAD

GROUND

LEAD

Fig.
47—Comfortron System Tester x

COMPLETE SYSTEM CHECKS

The following information should be used whenever

preliminary checks indicate the need for further, more

specific, tests. Together with the Electrical Test Dia-

gram (fig. 49) and the Vacuum Diagram (fig. 50),

they may be used to accurately pinpoint any malfunction

of the system.

Fig.
48—Comfortron Tester Installation

CHEVROLET OU
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-39

BROWN

BROWN

LT.
GREEN

BROWN

DK. GREEN

CONTROL

SWITCH

N-CAR
SENSOR

"—ORANGE—(36

[y—LT. GREEN

*)WWWW 55|—jg

TRANSDUCER

POWER SERVO

HIGH BLOWER MASTER FEEDBACK

DELAY DELAY POTENTIOMETER

THERMISTER THERMISTER

Fig.
49B-Comforrron Wiring Diagram-Underdash

CHEVROLET CHASSIS SERVICE AAANUAL

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

HEATER AND AIR CONDITIONING 1A-69

Fig.
96—Refrigerant and Vacuum Hoses (Corvette)

2.
Mount the sensor to the dash and connect the wires

to the Comfortron harness.

3.
Replace glove box assembly.

Control Head

The control head is attached to the instrument panel

flange in the same manner as the Four Season Control

Panel (See Figure 105). Two screws hold the head in

place. The amplifier, blower switch and servo and

defrost control cables are all part of the control head.

Amplifier

After the control head is removed from the instrument

panel, the amplifier may be removed as shown in Figure

107.

Temperature Dial Adjustment

1.
Install Tester J-22368 as previously described.

2.
Set Tester Voltage switch to Control Calibrate

position.

3.
Start the engine (fast idle) and set Comfortron

Control lever to HI-FRONT.

4.
Switch Rocker switch to MANUAL.

5. Set Manual Control Knob to 150 ohms on scale.

6. Rotate the Control Head Temperature Dial until the

voltmeter on the tester reads 6.5 volts. The Tem-

perature Dial should now indicate 75°.

7. If the Temperature Dial does not indicate 75°, insert

Tool J-21530 in slot to the left of the Dial as shown

in Figure 106.

8. With tool in position, rotate the Temperature Dial

so that it indicates 75°F.

Transducer

Figure 104 illustrates the installation of the transducer

assembly. Vacuum lines are clamped to the transducer

vacuum ports.
Fig.
97—Comfortron Vacuum Tank

CHEVROLET CHASSIS SERVICE JWANUAl

HEATER AND AIR CONDITIONING 1A-70

Fig.
98—Comfortron Thermal Vacuum Valve

Power Servo .

The Power Servo is attached, to the distributor duct.

The entire installation consists of the Servo Assembly

and its link assembly to the TEMP door. The Servo is

attached to the Air Selector Duct as shown in Figure 108.

Mode Shift Vacuum Diaphragm

Replacement

1.
Remove the heater distributor from the vehicle.

2.
Reach into the distributor through the AIR door

opening to reach and remove the vacuum diaphragm

mounting screws and diaphragm to door link screw

(remove piug from case to reach this screw).

3.
Reverse this procedure to replace.

4.
Adjust mode door without vacuum applied to dia-

phragm. The door should be open one inch from

sealing against the air distributor opening (inside of

case).
(Figure 109).
HIGH BLOWER

DELAY RELAY

.MASTER

DELAY

RELAY

Fig.
100—Comfortron Relays

COLLISION PROCEDURE-AII Systems

Whenever a car equipped with air conditioning unit is

involed in a collision or wreck, it should be inspected as

soon as possible. The extent of damage to any or all of

the component parts and the length of time the system

has been exposed to the atmosphere will determine the

replacement of parts and processing that will be re-

quired. The greater the length of time of exposure to the

atmosphere, the greater will have been the chances for

air, moisture and dirt to have entered and damaged the

system. Every case may be entirely different so it is not

possible to establish a hard and fast procedure to follow

each time. Good judgment must be used to determine

what steps should be taken in each specific case.

The following procedure is presented as a guide for

Fig.
99—Comfortron Resistor Assembly
Fig.
101—Comfortron Sensor Installation

CHEVROLET CHASSIS SERVICE MANUAL