1977 DATSUN PICK-UP wiring

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

Air

Conditioning

PERFORMANCE
TEST
DIAGNOSES

Condition

Discharge
air
too
warm

a
Both

discharge
and
suction

pres

sure
too

high

b
Both

discharge
and
suction

pres

sure
too
low

c
Discharge

pressure
too

high
and

suction

pressure
too
low

d
Suction

pressure
too

high
and

discharge

pressure
too
low

e

Discharge

pressure
normal
and

suction

pressure
too

high

t
Discharge

pressure
normal
and

luction

pressure
too
low

g
Suction

pressure
normal
and

discharge
pressure
too

high

h
Both

discharge
and
suction

pres

sure
normal

Air

conditioning
is

operating

properly

Discharge
air
normal

or
too
cold

a

Discharge
pressure
normal
and

suction

pressure
too
low
Probable
cause

Air

mixed
with
refrigerant
in

system

Overcharge
of

refrigerant

Loose
fan
belt
or

engine
over

heating

Obstructed
or

dirty
condenser
fins

Insufficient

refrigerant
charge

Over

filling
of

compressor
oil

Damaged
compressor
valve
or

pack

ing

Loose

compressor
drive
belt

Clutch

slippage

Faulty
expansion
valve

Clogged
expansion
valve
strainer

Water
has
frozen
at

expansion

valve

Faulty
expansion
valve

Faults
of
both

a
and
h
exist

Air
leaks
from

engine
com

partment

Restricted
air
flow

through
evapo

ratof

Slow
blower
motor

speed

AC
21
Corrective
action

Evacuate
and

charge
system

Discharge
some
of

refrigerant
to

correct
level

Adjust
fan
belt
or
check

cooling

system

Clean
exterior

surface
with
water

Add

refrigerant

Drain
oil
and
correct
oil
level

Refer

to

Compressor
oil
level

check

Repair
or

replace
compressor
Refer

to

Compressor

Adjust

Repair
Refer
to

Compressor

Reinstall

sensing
bulb
correctly
to

keep
it

tight
to

pipe

Replace

Clean
strainer

Evacuate
and

charge
system

Replace

Correct

sealing

Clean

evaporator
fins

Check
and

repair
blower
motor
and

wiring

Air

Conditioning

COMPRESSOR

DIAGNOSES

I
COMPRESSOR

TROUBLE

Turn
the

compressor
dutch
wheel

by
hand

I

I

If

OK
j

Will
not
turn

Apply
12V
direct

current
to

compressor
clutch

Then
check
clutch

engagement

I

j

If
OK
I

Internal

problem
in

compressor
cylinder

Repair
or

replace
compressor

Check

voltage
oflead
wire

for

compressor
on

cooler
cable

I

I

If
OK
I
Clutch
does
not

engage

I

Clutch
is

damaged

Repair
or

replace
dutch

assembly

No

voltage

I

Internal

problem
in

compressor

Repair
or

replace

compressor
Check
or

repair
wiring
system
for

compressor

clutch

AC
22

Air

Conditioning

BLOWER
MOTOR
DIAGNOSES

Blower
motor

inoperative

Check
fuse

In
fuse
block

15A
W

Single
fuse
15A
at

cooling
unit

I

j

If
OK

Check
the

continuity
and

fitting
of
fan
switch

I

I

If
OK

I

I

Connect
fan
switch
to

wiring
harness

2

Turn
the

ignition
switch
ON
IG

3
Set
fan
switch
at
ON
1
2
or
3

position

Check
the

voltage
for
blower
motor

Blue
lead
wire
is

poweI
source

Blue
wire

with
white

stripe
is

for

grounding

I

I
Voltage

I

I

Check
the

continuity
and

fitting
of
resistance
on

cooling
unit

I

I
If
OK
If

damaged

I
I

Replace
blower
motor
Replace
resistance

AC

24
mown
fuse

Replace
fuse

j

If

damaged

I

I

Replace
fan
switch

No

voltage

Replace
main
relay

Air

Conditioning

REMOVAL
AND
INSTALLATION

COMPRESSOR

REMOVAL

INSTALLATION

IDLER
PULLEY

FAN
BELT

TENSION
ADJUSTMENT

REMOVAL
AND
INSTALLATION

INSPECTION

COOLING
UNIT

REMOVAL
AND
INSTALLATION

DISASSEMBLY
AND
ASSEMBLY

INSPECTION

RECEIVER
DRYER
AND
PIPING

COMPRESSOR

REMOVAL

I
Remove

battery

2

Disconnect

compressor
lead
wire

at
connector

3
Loosen
idler

pulley
lock

nut
then

adjusting
bolt
Remove

compressor

drive
belt

from

compressor
pulley

AC477

Fig
AC
28

Removing
drive
belt

4

Discharge
system
Refer
to
Dis

charging
System
under
General
Service

section
CONTENTS

AC
25

AC25

AC26

AC
27

AC
27

AC27

AC
27

AC27

AC
27

AC
2B

AC
29

AC
29
REMOVAL

AND
INSTALLATION

INSPECTION

WIRING

HARNESS
AND

COMPONENTS

WIRING
DIAGRAM

MAINTENANCE

MAIN
RELAY

COMPRESSOR

RELAY

FAN
SWITCH

RESISTOR
FOR
FAN
SWITCH

THERMO
SWITCH

F
I

C
D
SOLENOID
VALVE
AC29

AC29

AC30

AC30

AC31

AC31

AC31

AC31

AC32

AC32

AC
32

5
Remove
flexible
hose

fixing
plate

and
disconnect
low
and

high
pressure

flexible
hoses
from

compressor

Notes

a
Use
two

wrenches
when
disconnect

ing
pipe

joints

b

Plug
flexible
hose
and

compressor

joint
openings
immediately
after

disconnection
to

prevent
entry
of

dust
moisture
laden
air
etc

Fig
AC
29

Disconnecting
ftexible

hoses

from
compressor

6
Remove

bolts

securing
fuel
tube

to

compressor
attachment

AC
25
Y
1

L

AC744

7
Remove
four
bolts

securing
com

pressor
to
its
bracket

Compressor
and

attachment

can
now
be
detached
as
an

assembly

Notes

a
There
are
a

total
of
four
bolts
two

on

upper
side
of
bracket
and
two

on
lower
side
of

compreSsor

Loosen

upper
bolts
and
remove

lower
bolts
When

removing
upper

bolts

securely
hold

compressor

with
one
hand

b
When

installing
temporarily
tighten

upper
bolts
then

tighten
lower

bolts

Ll1
1t

W
l
THERMO
SWITCH

I

I
Air

Conditioning

WIRING
HARNESS
AND
COMPONENTS

WIRING
DIAGRAM

BW
c
J

ii

1
l
BW

La

GL

FROM

LIGHT
SWITCH

CJ

Id

lW
f
8
L

rRl
@
W

I
FUSE
15A

1
J
D
CJ
B

B

o

J
I

B

y
i

jqt
0

noc
I
no
vi

1
J

mcl
y

yldru
ao
11
jblr
J

H
WJ1

q

2f
br
r
t

lH

iot
f1
tH
o
hm

I
l
i
I

1
rf
l
t
f
r

dt
ll
II

h
J

IiJ
l
I

d
hi

s
n

Jq

DDj
G
w
TG
r

i

i
It
U
JI1
GH
Jdf
J

t

ggo
J

10
lHohfth

gniJuo
lUb
Jl
VUlt
l0
H
2

1
19
i
tl
b

wt
IO
t
l
lo
J
I
l

l

to
tJ
b

YR
lStO
Y1

1
t
J
I

FUSE

I
II
nlWI

I
bn
f
w
1

U
QI
llnio

fiq
ni

I
tsH
W
tflt
fli
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lnl

O
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11

IJ
i
Ji

fjI
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11

i
ltll
ii
A
jll

I
I

I
gm
J
lIno
tl

Jl

JIIgiJ
l

1I0U
mflu
J
l
tllU
lJU

8
f
r
j

d

j
J
l1
Jlt

d
HInO
IG

to
l
VFJ
r1
rjJ
1

J
h
nI
0
i

IEvUID
l

il
1
i2
1

MN
k
B

gg

liii

gg
1

B
J

Ii
i
ELECTRIC

FUEL
PUMP

@
ILLUMINATION

CONTROL

RHEOSTAT

COLOR
CODE

B
Black

BW
Black
with
white

stripe

L
Blue

LW
Blue
with
white

stripe

LR
Blue
with
red

stripe

W
White

tll
G

GreeMnQ
r
iC
O
1

r

J
l
GL
Green
with
blue

stripe

R
L
Red
ith
blue

stripe

201011

lIt
J
m

I

W

tfli

I
o

lUll

IJ

Ub
OW

If
U
d

l

Q
I

ni

IGNITION
SWITCH

WIJIJJOO
W
l

Iuul
vomo
C

held

l

Jlb
vi
ia
1
1

tnd
15
W
le
llt

J
l

nq
LnJ

J
I
1

luil

mpHO
ibGt
L
D
lb

tldmoGl
nG
III
rbliw7
tHO

b
b
1
AC727

ns
1
j

fJ
l
YI
l
mtl
m
0
I

lfi
IO
fI
l

jg
h5
4
MjVj
IJC
p

i
W
i

1q

MAINTENANCE

Replace
any
wiring
harness
which
is

cracked
deteriorated
or

poorly
in

sulated

Always
replace
wire
with
those
of

the

same
diameter
Do

not
use
wire
of

smaller
diameter

Where

necessary
securely
retain

wire
harnesses
with

clips
or

tapes
so

that

they
will
not
be

frayed
or
worn

by
vibration

Notes

a

Repair
or

replace
any
electrical

part

which
is

questionable
or
likely
to

cause
a
short
circuit

When
disconnecting
battery
cables

always
disconnect

ground
cable
be

fore

positive
cable
Clean
battery

and
terminals
before

connecting

cables
then
connect

positive
cable

and

ground
cable
in

that
order

Apply
a
coat
of

grease
to
terminals

to

prevent
rust
formation

b
Do
not

attempt
to
conduct
a
con

tinuity
test
with
a

screwdriver
or

service
tools

always
use
test
lead

wires

c
Do
not

ground
terminals
when

circuits
are

open
or
unloaded

always
use

a
test

lamp
12V
3W

or
circuit
tester
as
a

load

MAIN
RELAY

Removal
and
Installation

The
main

relay
is
attached
to
the

cooling
unit

I

Disconnect

battery

ground
cable

2

Disconnect
main

relay
lead
wires

at
connector

3

Remove

cooling
unit

assembly

Refer
to
Removal
and
Installation

under

Cooling
Unit

4
Remove
the
screw

securing
main

relay
to

cooling
unit

and
detach
main

relay

5

To
install
main

relay
reverse
the

order

of
removal

Inspection

To

check

continuity
in

relay

circuit
use
a

test

lamp
or
an
ohm

meter

Continuity
between

points
3

and
4
should
exist
Air

Conditioning

When
a
12

volt
d
c
is

applied
across

points
3
and
4

continuity
between

points
I
and
2

should
also
exist

CD

00

COMPRESSOR
RELAY

Removal
and
installation

Disconnect

compressor
relay
lead

wires

at
connector

2
Remove

two
screws
securing
com

pressor
relay
to
receiver

dryer
and

detach

compressor
relay

3
To
install

compressor
relay
reo

verse
the
order
of
removal
@

I
ul

CDe
JOO

ID
IDe

@e

L

AC465

Fig
AC
42
Main

relay

Inspection

Using
a
test

lamp
or

an
ohmmeter

make

sure
that

compressor
relay
con

tacts

open
and

close
con

tinuously

Continuity
always
exists
between

points
3
and
4
When

current
flows

through

points
3

and
4

points
1

and
2
close
This

causes
current
to

flow

through
1
and
2

FAN
SWITCH

Removal
and
installation

1
Disconnect

battery
ground
cable

2
Remove

screws

securing
console

box
Withdraw
console
box
forward

and
disconnect
lead
wire
connector

3
Detach
switch
knob

4
From
rear
side
of
console
box

remove
screws

securing
switch
and

remove
switch

5
To
install
fan
switch
reverse
the

order
of
removal

AC
31
i
t
v

J

AC489

Fig
A

C
43
Compressor
relay

AC771

Fif
AC

44
Removing
fan
switch