1977 DATSUN PICK-UP Service Manual

Body
Electrical

System

TROUBLE
SHOOTING
GUIDE

Condition

Warning
lamp
does
not

light
in
START

posi

tion

of

ignition
switch
Probable
cause

Burnt
or

loose
bulb

Faulty
f1o
r

temperature
relay

Loose
connection

or

open
circuit

BE
44
Corrective
action

Replace
bulb

or
correct
bulb
socket

Conduct

continuity
test
and

repair
or
reo

place

Refer
to
Section

EC

Check

wiring
and
or

repair
if

necessary

SE

B
V
I

C
E

1

M
A
N
I
I

A
I

W

u
71i

c

i

L

DATSUN
PICK
UP

MODEL
620

SERIES

lm

SSANJ

NISSAN
MOTOR
CO
LTD

TOKYO
JAPAN
SECTION
AC

AIR

CONDITIONING

DESCRIPTION
AC
2

TROUBLE
DIAGNOSES
AND

AC
19

CORRECTION

REMOVAL
AND

INSTALLATION
AC
25

COMPRESSOR
AC

33

SPECIAL
SERVICE
TOOLS
AC
39

OUTLINE
OF
AIR
CONDITIONER

REFRIGERATION

SYSTEM

CONDENSER

COMPRESSOR

RECEIVER
DRYER

COOLING
UNIT

ELECTRICAL
CIRCUIT

OUTLINE
OF
AIR

CONDITIONER

The

air
conditioner
consists

es

sentially
of
a

cooling
unit

compressor

condenser
receiver

dryer
and

piping

The

cooling
unit

secured
with

three

brackets
is
a

ttached
to
the

location

occupied
by
the

package

tray

in
the
dash

panel

The

cooled
air
from
the
duct

is

directed
into
the

passenger
compart
Air

Conditioning

DESCRIPTION

CONTENTS

AC
2

AC3

AC
3

AC3

AC4

AC4

AC
5
DESCRIPTION

MAIN

RELAY

FAN
SWITCH

THERMO

SWITCH

PRESSURE
SWITCH

COMPRESSOR
RELAY

F
I
C
D

SOLENOID
VALVE
AC
5

AC
7

AC
7

AC
7

AC
7

AC
7

AC
7

ment

through
the
three

outlets
at

the

instrument

panel

The

compressor
serves
to

compress

the

vaporized
refrigerant
and
is
attach

ed

through
the
bracket
to
the
loca

tion

occupied
by
the

mechanical
fuel

pump
on
the

engine

The
condenser
cools
the

compres

sed

refrigerant
vapor
sent

by
the
com

pressor
and
is

located
on

the
front
of
the
radiator
in

the

engine
compart

ment

The
receiver

dryer

serving
as
a

reservoir

for

storage
of
the

liquid
sent

by
the
condenser
is

located
on
the

right
in
the

engine
compartment

The

piping
consists
of

two
flexible

hoses

and
five

copper
tubes
which

connect
various

components
of
the

air

conditioning
system

I

Cooling
unit

2

Expansion
valve

3
Receiver

dryer

4

Comressor
5

Condenser

6
Duct

@
Flexible
hose

@
Copper
tube

AC
2
AC724

Fig
AC
1

Cooling
system

REFRIGERATION

SYSTEM

If

you
were
to

paint
your
finger

with
alcohol

your
finger
would
feel

cold
This
is
because
the

liquid
alcohol

takes
heat

away
from

your
finger

while
it

evaporates
If
a

quickly
evapo

rating

liquid
such
as
alcoliol
is

placed

in
a
container
inside
a
box
the
tem

f

Outside
air

U

Condenser

J6G1
i
i

1
1

t1

1

ilill
I
I

J

JJ
LlJ
i
l

7

U

Receiver

dryer

h

w

t

CONDENSER

The
condenser
is
installed
to
the

front
of
the
radiator

The
heated
and

compressed

refrigerant
gas
from
the
Air

Conditioning

perature
inside
the
box
will

drop
This

is
because
the

alcohol
is

evaporated

absorbing
the
heat
from
the
air

insidc

the
box
If
the

gaseous
alcohol
is

collected
and

cooled
with

cold
water

it
will
be

changed
back

into
a

liquid
by

absorption
of
its
heat

by
the
cold

water

The
cooler

operates
on
this

princi

Compressor

t

q
ttLJ

IrJ

Evaporator
It

J

1

J

f
9

d

lUr

I

Expansion
valve
V7777
J
High
pressure

lLLLLL
l

gas

I
I
High
pressure

liquid

t

u

compressor
condenses
to
a

liquid
by

being
cooled

by
air

passing
between

the
fins
of
the
condenser

1
GJ
7

vlmnn

iii

plI

d1i
1il

Ac459

Fig
AC

3
Condenser

AC3
pIe
The

liquid
used

is
the

refrigerant

R
12

The
heat
inside
the

passenger

compartment
is
absorbed

by

changing

the

refrigerant
from
a

liquid
to
a

gas

and
then

dissipated
to
the

outside

by

changing
the

refrigerant
from

a

gas

back
to
a

liquid

The

refrigeration
system
is

shown

in

Figure
AC
2

Low

pressurt

liquid

1

I
L2
Low

pressure

gas

Inside
air

li

r

L

Blower
motor

AC458

Fig
AC
2

Refrigeration
cycle

COMPRESSOR

The

compressor
is
installed
to
the

side

of
the

engine
and
is
driven

by

crank

pulley
through
a
belt
The

refrig

erant

gas
leaving
the

evaporator
is

forced
out
to
the
condenser

by
com

pressor
and
the
low

pressure
refrig

erant

gas
is

compressed
to
a

high

pressure
and

high

temperature

The

driving
force
is
transmitted

by

an
electrical
clutch
Because

engine

rpm
is

very
low

during
idling
the

clutch
will

not
transmit

the

driving

force
thus

ensuring
smooth

engine

idling

Air

Conditioning

RECEIVER
DRYER

The
receiver

dryer
serves
the

pur

pose
of

storing
the

liquid
refrigerant

The

amount
of
the

liquid
refrigerant

flowing
through
the

system
varies

with

the

operating
condition
of
the
air

conditioner
To
be
accurate
the

receiver

dryer
stores

excess
amount
of

refrigerant
when

the
heat
load
is

lowered
It

also
releases
stored

refriger

ant
when

additional

cooling
is
needed

thus

maintaining
the

optimum
flow
of

refrigerant
within
the

system

The
receiver

dryer
includes

a

strainer
and
desiccant

They
have
the

job
of

removing
moisture
and

foreign

particles
as
the

refrigerant
circulates

within
the

system

The

pressure
switch

is
installed

beside

sight
glass
of
receiver

dryer
The

purpose
of
the
switch

is
to

stop
the

compressor
operation
in
the
event

an

excessive

system

pressure
builds

up
on

the

high
pressure
lines
AC728

Fig
A
C
4

Compressor

To
e

ran
ion
alve

From
condenser

5

c
FJi

i

1

Z

i

3

c

o

I

COOLING
UNIT
o

L

o

W
7
R
o
3

J
J
r

t

AC230
I

Prc
surc
switch

2

Sight
glass

3
Strainer

4
De
kcant

Fig
AC
5
Receiver

dryer

The

liquid
refrigerant
evaporates
in

the

evaporator
with

the
aid
of
the

expansion
valve

Consequently
the
air

drawn

by
the
blower
motor
is

cooled

in

passing
through
the

evaporator

The

expansion
valve
restricts

the

liquid
refrigerant
as
it

passes
through
it

and

delivers

sprayed
refrigerant
to
the

evaporator
for

facilitating
refrigerant

evaporation
The

cooling
unit

includes
an

evapo

rator
and
an

expansion
valve
From

the
electrical

point
of
view

the

cooling
unit
consists
of
a

blower

motor

a
resistor
for
fan

speed
control

and
some
switches
and

relays

AC
4

The

refrigerant
within
the

thermo

bulb

changes
in

pressure
through
the

super
heat

condition
of

vaporized
re

frigerant
gas
which
comes
out
of
the

evaporator
causing
the

deflection
of

the

diaphragm
The
lift

of
the

ball

valve
attached
to
the

diaphragm
is

changed
by
the
deflection
of
the
dia

phragm
thus

controlling
the
amount

of

refrigerant
passing
the

orifice

ELECTRICAL
CIRCUIT

DESCRIPTION

The

electrical
circuit

of
the
air

conditioner
consists
of
four
switches

two

relays
a
solenoid
valve
a
fan

motor
and
a

compressor
magnetic

clutch
Air

Conditioning

Diaphragm

Orifice

Valve
ball

AC729
4

Sensing
bulb

Fig
A
C
6

Expansion
value

The

following
wiring
diagram

pro

vides
a

complete
description
of
the

whole
circuit

When
the

ignition
switch
and
the

fan
switch
are
ON
the
main

relay
is

activated

causing
battery
power
to

flow

through
the
fan
motor
and
the

magnetic
clutch
The

magnetic
clutch

is

activated

by
the
thermo
switch

AC
5
000

l

1
Motor

2
Fan

3
Lower

case

4

Cooler
duct

5

Evaporator

6

Expansion
valve

7

Upper
case
8
Resistor

9

Main

relay

10
Thermo
switch

II
Cable

clamp

12

Cable

13
Harness

AC725

Fig
AC
7

Cooling
unit

pressure
switch
and

compressor
relay

The

blower
motor
fan

speed
is

con

trolled

by
the
fan
switch
and
resistor

The
solenoid
valve
is

also
activated

This
in
turn

causes
the

fast
idle
control

device
F
l

C
D
to
increase

engine

speed
when
the

vehicle
is

at
rest
with

the

engine
ON

1
I

6

I

BA

RY

i
Air

Conditioning

BW
c
J

BW

n
B

m

00
L
ELECTRIC

FUEL
PUMP

oB

tl

b@

L

t

FROM
LIGHT

SWITCH

c
J

LW
2
L

rRL
fZP
W

I
FUSE
15A

J
D
CJ
B

1
COMPRESSOR
RELAY
B

GL
I

lL

GL1J
ILLUMINATION

CONTROL

RHEOSTAT

3

ILLUMINATION

LAMP

I

I
MAIN
RELAY

FAN
SWITCH

I

r

1

UE
H

I

I
THERMO

SWITCH

COLOR

CODE

@

IC
PRESSU
1

rlTCH

D
D

G
c
J
oc

I
m

f
F
I
C
D

SOLENOID

COMPRESSOR

FUSE
LR

I

BW
O

W

ov
J

I

IG
0

0

OVJ

AC

6
B

BW

L

LW

LR

W

G

GL

RL
Black

Black
with
white

stripe

Blue

Blue
with

white

stripe

Blue
with
red

stripe

White

Green

Green
with

blue

stripe

Red
with
blue

stripe

IG

BW
t
1

n

L

IGNITION
SWITCH

AC727

Fig
A
C
B

Wiring
diagram
of
air
conditioner

system

MAIN
RELAY

The
main

relay
is
located
on
the

cooling
unit

When
the

ignition
switch
and
fan

switch

are
both
turned
on
the

COll

@

FAN
SWITCH

The

fan
switch

serving
as
a
control

unit
is

installed
on
the
center
console

This
switch

controls
the

blower
motor

speed
through
the
resistor
It
is
also

used
as
a

main

relay
switch

Fig
AC
I0
Fan
switch

THERMO

SWITCH

The
thermo

switch
is

located
on
the

upper
side
of
the

cooling
unit
and
is

controlled

by
the

cable
and
the
con

trollever
attached
to
the
console
box

It
is
so

designed
that
when
the
air

passing

through
the

evaporator
core
is

cooled
down

to
the

predetermined
Air

Conditioning

tacts
in
the

relay
are
closed
Then

electrical

power
from
the

battery
is

supplied
to
the
blower

motor
and
the

electrical
clutch
for
the

compressor

@

Dc

IDe

ID
1
1

l@

@
e

L
J

AC465

Fig
A
C
9
Main

relay

temperature
set

by
the

control
lever

it

automatically
turns

off
When
the

switch
is
turned
off
the

magnetic

clutch
is

turned
off

stopping
the
flow

of

refrigerant
inside
the

cooling
system

and

increasing
the

cooling
system
tem

perature

When
the

air
rises
to
the

pre

determined

temperature
the
thermo

switch

automatically
turns

on
In
this

way
the

temperature
of
the
air
dis

charged
from
the

cooling
unit
is
auto

matically
controlled
as
desired

PRESSURE

SWITCH

The

pressure
switch
is
turned
off

when

refrigerant
pressure
in
the

cooling
system
rises
to

an

abnormally

high
level
28

kg
cm2

398

psi
This

in

turn
turns
off
the

compressor

magnetic
clutch

actuating
the
com

pressor
relay
and

gradually
decreasing

pressure
in
the

cooling
system
When

the

pressure
drops
to
or
below
24

kg
cm2
341

psi
the

pressure
switch

again
turns
on

Thus

cooling

system
refrigerant

pressure
is

automatically
maintained
at

the

proper
value

a
t
all
times

AC
7
COMPRESSOR
RERAY

The

compressor
relay
is

attached
to

the
receiver

dryer
bracket
on
the

right

side

of
the

engine
compartment
This

relay
is

actuated
by
the

fan
switch

thermo
switch

and

pressure
switch
to

turn
on

and
off
the

compressor

magnetic
clutch

cv

1

2

AC731

Fig
A
C

11
Pressure
switch
and

compressor
relay

F
I
C
D
SOLENOID
VALVE

The
F
l
C
D
solenoid

valve
is
at

tached
to
the
dash

panel
in
the

engine

compartment
This
valve

supplies
vacu

um
to
the

F
I

C
D

diaphragm
through

the
vacuum
hose
connected

to
the

engine
intake
manifold
when
the

engine
is

at
idle
and

the

cooling
system

is
ON

thereby
raising
idle

speed
to
the

predetermined
rpm
800

IW

r

e

I

1
s

AC132

Fig
AC
12
F
l
C
D
solenoid

value