Carrier 38AD Dimensions and installation guide

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Condensing

Units

Air-Cooled

—

Remote

INSTALLATION

Lifting

Unit

—

Do

not

sling

unskidded

unit.

Use

spreader

bars

to

prevent

slings

from

damaging

unit

panels.

Do

not

roll

unskidded

unit

on

pipes

or

rollers.

Skid

Removal

—

Remove

the

4

bolts

holding

top

frame

in

place

and

lift

frame

from

unit.

Remove

compressor

compartment

end

panel.

Raise

and

block

up

compressor

end

of

unit

about

10

inches.

Remove

4

bolts

and

nuts,

2

in

end

corners

and

2

where

compressor

and

condenser

sections

meet.

Lower

unit.

Raise

and

block

opposite

end.

Remove

remaining

2

bolts

and

nuts.

Position

Unit

so

air

flow

is

unrestricted

for

at

least

2

ft

on

each

side,

3

ft

on

each

end,

and

for

at

least

5

ft

above

unit

top.

See

Fig.

1.

Erect

Unit

using

legs

attached

to

unit

base

skid.

Block

up

or

suspend

unit.

Bolt

leg

to

each

corner

of

unit.

Bolt

2

legs

to

bottom

of

unit

where

compressor

and

coil

sections

meet.

Lower

unit.

Compressor

Mounting

—

As

shipped,

compressor

is

held

tight

by

self-locking

bolts.

BEFORE

STARTING

UNIT

-

Loosen

self-locking

bolts

until

the

flanged

washer

is

still

snug

but

can

be

moved

sidewise.

Do

not

remove

shipping

bolts.

V

KtGGiNG

POINTS

<4)

HOLES

LEGEND

1

-3/8~>rs.

ODE

Suction

Line

Conn.

2-1/2-in.

Oiaro

Hote

5/8-in.

ODE

Liquid

Line

Conn.

7/8-in.

Diem

Hote

3/4-in.

Thermostat

Conn.

7/8-in.

Diem

Hote

D

—

l-T/4-in.

Electrical

Conn.

1-3/4-in.

DiarrrHote

E

—

3/4-in.

Fan

Coil

Control

Wire

Conn.

7/8-in.

Diam

Hole

Certified

dimension

drawings

are

avaite&te

on

request.

Fig.

1

—

Physical

Data

and

Dimensions

©

Carrier

Corporation

1971

Form

38AD-4SI

Table

1

—

Physical

Data

(60-Hz)

UNIT

38AD

012

014

016

OPER

WT

(lb)

770

805

970

REFRIGERANT

22

22

22

COMPRESSOR

Recip

Hermetic

6

Cyl;

1750

Rpm

Model

No.

06DD328

06DD537

06DD537

Oil

(pts)

Suniso

3GS

or

Capella

Bl

10

10

10

Crankcase

Htr

Watts

75

75

75

Unloader

Setting

Load

70

±

1

psig

70

±

1

psig

70

±

1

psig

Unload

60

±

2

psig

60

±

2

psig

60

i

2

psig

OUTDOOR

AIR

FANS

Axial

Flow;

Direct

Drive

No.

...Rpm

2...1085

2

..1085

3...1120

Diam

(in.)

22

22

22

Motor

Hp

(NEMA)

l

/

2

%

l

/

2

Nom

Cfm

Total

8800

8000

13,000

CONDENSER

COIL

Face

Area

(sa

ft)

Storage

Cap.

(lb)*

19

1

19.1

26.2

17.7

26.5

51

CONTROLS

Pressurestat

Settings

High

Cutout

400

±

5

psig

400

±

5

psig

364

±

5

p

s

i

g

Cut-In

300

±20

psig

300

±

5

psig

264

±

15

psig

Low

Cutout

29

±

5

psig

29

±

5

psig

29

±

5

p

sig

Cut-In

64

±

10

psi

g

64

+

10

psig

64

±

5

psig

Fan-Cycling

Thermo.

No.

2

Opens

Closes

60

±

2

F

60

±

2

F

70

F

65

±

4

F

65

±

4

F

75

F

No.

3

Opens

—

-

57

F

Closes

-

-

62

F

FUSIBLE

PLUG

200

F

200

F

200

F

*Storage

capacity

is

with

condenser

80%

full

of

liquid

R-22

at

130

F

for

38AD012

and

014,

and

120

F

for

38AD016.

Fan-Cycling

Thermostat

temperature

sensing

bulb

and

coiled

capillary

are

taped

to

compressor

conduit

in

compressor

compartment

for

shipment.

Carefully

remove

tape

and

uncoil

capillary.

Route

bulb

and

capillary

behind

compressor

and

out

of

compressor

compartment

thru

space

under

right-hand

condenser

coil.

Do

not

kink

or

damage

capillary

or

sensing

bulb.

Position

sensing

bulb

in

inlet

airstream.

With

mounting

clamp

and

hardware

provided

in

parts

package,

secure

sensing

bulb

to

lower

tube

sheet

near

compressor

so

that

it

does

not

touch

coil

fins.

Be

sure

airstream

across

bulb

is

unrestricted

and

that

bulb

does

not

receive

direct

sunlight.

Refrigerant

Line

Sizes

will

depend

on

length

of

piping

required

between

condensing

unit

and

evaporator.

Consideration

must

be

given

to

liquid

lift

and

to

compressor

oil

return

(see

Table

2).

Refer

to

Part

3

of

Carrier

System

Design

Manual

for

design

details

and

line

sizing.

Refer

to

Evaporator

Installation

Instructions

for

additional

information.

Refrigerant

Drier

and

Moisture

Indicator

—

A

filter-

drier

and

a

liquid-moisture

indicator

are

shipped

with

unit

for

field

installation

(Table

2).

Install

according

to

manufacturer’s

instructions.

Receiver

—

No

receiver

is

provided

with

unit.

It

is

recommended

that

one

not

be

used.

Piping

Procedure

—

Do

not

remove

plastic

dust

plugs

from

suction

and

liquid

line

stub

in

compressor

compartment

until

piping

connections

are

ready

to

be

made.

Pass

nitrogen

or

other

inert

gas

thru

piping

while

brazing,

to

prevent

formation

of

copper

oxide.

Install

field-supplied

thermostatic

expansion

valve(s)

to

evaporator

section.

If

two

thermostatic

expansion

valves

are

installed

for

two-step

cooling,

install

field-supplied

liquid

line

solenoid

valve

ahead

of

second

expansion

valve.

Install

filter-drier

in

the

common

liquid

line

just

ahead

of

both

expansion

valves.

Table

2

—

Liquid

Line

Data

UNIT

MODEL

38AD

MAX

ALLOW.

LIQUID

LIFT

(ft)

LIQUID

LINE

Max

Allow.

Press.

Drop

(psi)

Max

Allow.

T

emp

Loss

(F)

Fi

Iter-Drier

and

Sight

Glass

Flare

Conn.*

(in.)

012

75

7

1.5

%

014

50

7

1.5

5

/»

016

78

7

1.0

%

*lnlet

and

outlet

Safety

Relief

—

A

fusible

plug

is

located

on

com¬

pressor

crankcase

(Fig.

2).

Do

not

cap

this

plug.

If

local

code

requires

additional

safety

devices,

install

them

as

directed.

Fig.

2

—

Tee

Connection

Power

Wiring

—

Unit

is

factory

wired

for

voltage

shown

on

nameplate.

Provide

an

adequate

fused

disconnect

switch

within

sight

of

unit

and

out

of

reach

of

children.

Provision

for

locking

switch

open

(off)

is

advisable

to

prevent

power

from

being

turned

on

while

unit

is

being

serviced,

especially

if

disconnect

is

not

visible

from

unit.

Disconnect

switch,

fuses,

and

field

wiring

must

comply

with

National

Electrical

Code

and

local

requirements.

Route

power

wires

thru

openings

in

unit

bottom

panel

to

connections

in

unit

control

box

as

shown

on

unit

label

diagram

and

Fig.

3.

Unit

must

be

grounded.

Affix

crankcase

heater

power

warning

sticker

to

unit

disconnect

switch.

Fig.

3

—

Main

Power

Supply

Table

3

—

Electrical

Data

(60-Hz)

V/PH

MWA

ICF

FU

COMPR

Norn

Min-Max

FLA

LRA

410

208/3

187-229

68

198

80

49.3

191

510

230/3

198-254

62

179

70

44

3

172

U

1

z

610

460/3

414-506

31

89

35

22.2

86

no

575/3

518-632

24

71

30

17.9

69

400

208/3

187-229

86

184

100

63.6

266

3

2

500

230/3

198-254

78

166

90

57.

%

3

2

600

460/3

414-506

39

123

45

28

6

120

1

6

100

575/3

518-632

32

99

35

22.9

96

1.0

fTjTSJ

208/3

187-229

86

184

100

64.0

266

3

2

Kin

230/3

198-254

78

166

90

58.0:

Mii/240

3.2

K

11

460/3

414-506

39

123

45

29.0

120

1.6

Euj

575/3

518-632

32

99

40

23.0

96

1

0

Values

are

for

part-winding

start.

FLA

—

Full

Load

Amps

FU

—

Fuse

(max

allowable

amps;

dual

element)

ICF

—

Max

Instantaneous

Current

Flow

(during

start-up;

sum

of

compressor

LRA

plus

F

LA

of

all

other

motors

in

the

unit)

LRA

—

Locked

Rotor

Amps

MWA

—

Minimum

Wire

Amps

per

NEC

*Units

38AD012

and

014

have

two;

unit

38AD016

has

three.

Control

Circuit

Wiring

—

Control

voltage

is

115

volts.

Install

a

field-supplied

115-volt

thermostat

with

minimum

rating

of

one

amp

(Fig.

4).

If

a

24-volt

thermostat

assembly

is

to

be

used,

install

Accessory

Relay

Package

38AD900001

(Fig.

5)

above

terminal

board

(TB2)

in

unit

control

box.

Three

field-supplied

no.

10

sheet

metal

screws

are

required.

Control

box

back

panel

holes

are

predrilled.

115-Volt

Accessories

Winter

Start

Control

(if

required)

—

Reset

and

relocate

the

unit

low

pressurestat

and

install

field-supplied

defrost

thermostat

(Carrier

part

no.

50BB900001).

LOW

PRESSURESTAT

-

Isolate

compressor

by

frontseating

discharge

and

suction

service

valves.

Relieve

compressor

pressure.

Reset

the

unit

low

pressurestat

to

5

psig.

Disconnect

the

low

pressure¬

stat

capillary

from

compressor

crankcase

and

cap

the

unused

1

/4-in.

flare

fitting

on

the

compressor.

Backseat

liquid

line

service

valve

to

shut

service

port.

Connect

the

low

pressurestat

capillary

to

the

liquid

line

service

valve

service

port.

Open

service

port

and

compressor

service

valves.

DEFROST

THERMOSTAT

-

Control

is

not

water¬

proof

or

moisture

resistant.

Protect

control

against

direct

contact

with

moisture

or

condensation

of

moisture

on

switch

insulator.

Mount

control

with

approximately

2

in.

of

top

of

thermostat

capillary

passing

thru

lower

part

of

evaporator

coil

and

with

remainder

of

capillary

inserted

between

fins

on

entering

air

side

of

coil.

Connect

thermostat

electrical

contacts

into

indoor

cooling

thermostat

circuit

or

in

series

with

compressor

holding

coil.

NOTE:

Defrost

thermostat

must

be

used

on

all

systems

operating

with

outdoor

temperatures

below

45

F.

24-Volt

Accessories

Motormaster®

(32

Series)

Head

Pressure

Controller

—

Refer

to

Installation

Instruction

shipped

with

this

accessory

plus

the

following

information.

Control

box

and

sensor

(thermistor)

location

is

shown

in

Fig.

6.

Electrical

connections

are

shown

in

Fig.

7.

Refer

to

unit

label

diagram

as

required.

Fig.

6

—

Motormaster®

Control

Box

and

Sensor

Location

3

473

Fig.

7

—

Motormaster®

Electrical

Connections

On

208-,

230-

and

460-volt

units,

outdoor

fan

motor

no.

1

(OFMi)

is

suitable

for

use

with

Motor-

mastei®

without

modification.

On

575-volt

units,

install

a

field-supplied

1

kva

transformer

(Carrier

part

no.

HT01AH959)

and

replace

575-volt

outdoor

fan

motor

no.

1

with

230-1-60

motor

(Carrier

part

no.

HC44VL851

or

HC44VE851)

and

add

field-supplied

capacitor

(Carrier

part

no.

HC96FH007).

INITIAL

START-UP

Evacuate

and

Dehydrate

the

entire

refrigerant

system

by

either

of

the

methods

described

in

the

Carrier

Standard

Service

Techniques

Manual,

Chapter

1,

Section

1-7.

Leak

Test

the

entire

refrigerant

system

by

the

pressure

method

described

in

the

Carrier

Standard

Service

Techniques

Manual,

Chapter

1,

Section

1-6.

Use

R-22

at

approximately

25

psig

backed

up

with

an

inert

gas

to

a

total

pressure

not

to

exceed

245

psig.

Before

Starting

Unit

check

the

following:

1.

Compressor

oil

level

must

be

at

least

within

sight

in

each

compressor

crankcase.

Add

oil

if

necessary.

2.

Compressor

hold-down

bolts

must

be

snug

but

not

tight.

Refer

to

Installation

Instructions

or

tag

on

compressor

foot.

3.

All

internal

wiring

connections

must

be

tight;

all

barriers

and

covers

must

be

in

place.

4.

Electrical

power

source

must

agree

with

unit

nameplate

rating.

5.

All

service

valves

must

be

open.

6.

Crankcase

heater

must

be

firmly

locked

into

the

compressor

crankcase.

Energize

Branch

Circuit

—

Set

room

thermostat

above

ambient.

Close

field

disconnect

switch.

Be

sure

that

compressor

crankcase

heaters

are

opera¬

ting.

Allow

crankcase

heaters

to

operate

a

mini¬

mum

of

24

hours

before

starting

unit.

To

Start

Unit

set

room

thermostat

below

ambient.

After

starting

unit

there

will

be

a

delay

of

at

least

15

seconds

before

compressor

starts.

To

Charge

System

—

Add

refrigerant

to

system

using

weight

method

as

described

in

Standard

Service

Techniques

Manual

plus

the

following:

1.

Before

starting

compressor,

charge

system

with

initial

charge

for

liquid

seal

(Table

4).

2.

Start

condensing

and

evaporator

units

and

charge

to

a

clear

sight

glass

using

Charging

by

Sight

Glass

procedure.

Restrict

air

flow

thru

condenser

coil

with

a

sheet

of

plywood

or

cardboard

to

achieve

condensing

temperature

shown

in

Table

4.

3.

Add

additional

refrigerant

vapor

as

shown

in

Table

4

to

fill

subcooler

coils

using

Charging

by

Weight

Procedure.

After

Charging

System

allow

unit

to

run

for

about

20

minutes.

Stop

unit

and

check

compressor

oil

level.

Add

oil

only

if

necessary

to

bring

oil

into

view

in

sight

glass.

If

oil

is

added,

run

unit

for

additional

10

minutes.

Stop

unit

and

check

oil

level.

If

level

is

still

low,

add

oil

only

after

determining

that

piping

system

is

designed

for

proper

oil

return

and

that

the

system

is

not

leaking

oil.

Check

the

operation

of

all

safety

controls.

Replace

all

service

panels.

Be

sure

that

control

panel

cover

is

closed

tightly.

Table

4

—

Charging

Data

(R-22)

UNIT

MODEL

38AD

REFRIG

CHG

(lb)

CONDENSING

TEMPERATURE

DURING

CHARGING

(F)

Initial

For

Liquid

Seal

Sub

Cool

er*

012

10

3

130

014

13

2

130

016

14

6

120

*For

maximum

system

capacity

without

receiver

NOTE:

Values

shown

do

not

include

charge

requirements

for

cooling

coils

and

system

piping

SERVICE

Capacity

Control

is

accomplished

by

a

suction

pressure

actuated

unloader

which

controls

two

cylinders.

Unloaders

are

factory

set,

as

shown

in

Table

1,

but

may

be

field

adjusted.

CONTROL

SET

POINT

(cylinder

load

point)

is

adjustable

from

0

to

85

psig.

To

adjust,

turn

control

set

point

adjustment

nut

(Fig.

8)

clockwise

to

its

bottom

stop.

In

this

position,

set

point

is

85

psig.

Then,

turn

adjustment

counterclockwise

to

desired

control

set

point.

Every

full

turn

counter¬

clockwise

decreases

set

point

by

7.5

psig.

4

474

CONTROL

SET

POINT

ADJUSTMENT

NUT

PRESSURE

DIFFERENTIAL

ADJUSTMENT

SCREW

VALVE

BODY

DIFFERENTIAL

SCREW

SEALING

CAP

(CAP

MUST

BE

REPLACED

TO

PREVENT

REFRIGERANT

LEAKAGE)

Fig.

8

—

Compressor

Capacity

Control

Unloader

PRESSURE

DIFFERENTIAL

(difference

between

cylinder

load

and

unload

points)

is

adjustable

from

6

to

22

psig.

To

adjust,

turn

pressure

differential

adjustment

screw

(Fig.

8)

counterclockwise

to

its

back

stop

position.

In

this

position,

differential

is

6

psig.

Then,

turn

adjustment

clockwise

to

desired

pressure

differential.

Every

full

turn

clockwise

increases

differential

by

1.5

psig.

Compressor

Lockout

Circuit

—

Units

38AD012

and

014

have

a

control

to

provide

positive

com¬

pressor

lockout

protection

if

an

overcurrent

or

overtemperature

device

trips

out.

The

over

current

protection

devices

(thermally

actuated,

automatic

reset

overloads)

are

located

in

compressor

terminal

box.

Also,

an

overtemperature

thermostat

is

im¬

bedded

in

compressor

motor

windings

on

“across-

the-line

start”

units.

The

“part-winding-start”

units

have

a

thermostat

externally

mounted

on

compres¬

sor

body.

TO

RESTART

COMPRESSOR

-

After

determin¬

ing

cause

of

compressor

lockout

and

performing

required

corrective

action,

push

reset

button

on

control

box

door.

The

lockout

circuit

will

automatically

reset

after

shutdown

due

to

power

failure.

Time

Guard

Circuit

for

each

compressor

provides

for

a

5-minute

delay

before

restarting

compressor

after

shutdown

for

any

reason.

On

start-up,

the

Time

Guard

Timer

causes

a

delay

of

15

seconds

after

thermostat

closes,

and

fans

start

before

compressor

will

start.

On

38AD012

and

014;460-

and

575-volt

units

outdoor

air

fan

no.

2

starts

up

with

compressor.

On

compressor

shutdown

the

timer

recycles

for

4

minutes

45

seconds.

During

this

time

the

compressor

cannot

restart.

Head

Pressure

Control

—

A

feeler

bulb

in

the

condenser

inlet

airstream

senses

temperature

of

air

entering

condenser

to

control

no.

2

fan

on

38AD012

and

014

and

no.

2

and

3

on

38AD016.

Qpen

and

close

temperatures

of

switch

are

shown

in

Table

1.

Be

sure

that

feeler

bulb

is

not

in

direct

contact

with

coil

surface.

See

INSTALLATION,

Fan

Cycling

Thermostat.

MOTORMASTER®

SOLID

STATE

HEAD

PRES¬

SURE

CONTROLLER

(32

Series

accessory)

may

be

used

on

these

units.

Controller

modulates

rpm

of

no.

1

condenser

fan

motor

from

zero

to

full

speed

to

provide

condensing

pressure

control

and

operation

at

lower

ambient

temperatures.

On

460-volt

units,

install

a

field-supplied

trans¬

former

and

rewire

condenser

fan

motor

no.

1

for

230

volts.

On

575-volt

units,

install

a

field-supplied

trans¬

former

and

replace

575-volt

motor

with

230-volt

motor

(Carrier

part

no.

HC44VL851

or

HC44VE851).

Crankcase

Heater

prevents

refrigerant

migration

and

compressor

oil

dilution

during

shutdown

whenever

compressor

is

not

operating.

Both

compressor

service

valves

must

be

closed

whenever

crankcase

heater

is

de-energized

for

more

than

six

hours.

Fan

Adjustment

-

Turn

unit

power

off.

Remove

fan

guard

and

loosen

hub

setscrew.

Adjust

fan

until

top

surface

of

hub

is

3/8

in.

below

top

of

venturi

rim

as

shown

in

Fig.

7.

Then,

tighten

setscrew

on

flat

of

motor

shaft.

Replace

rubber

hubcap.

If

rubber

hubcap

is

missing,

seal

fan

hub

recess

with

permagum

to

prevent

hub

from

rusting

to

motor

shaft.

Lubrication

FAN

MOTORS

have

sealed

lubricated

bearings.

No

provisions

for

lubrication

are

made.

COMPRESSOR

has

its

own

oil

supply.

Loss

of

oil

due

to

a

leak

in

the

system

should

be

the

only

reason

for

adding

oil

after

the

system

has

been

in

operation.

Fig.

9

—

Fan

Adjustment

5

To

Add

or

Remove

Compressor

Oil

1.

Pump

down

compressor

to

2

psig

and

close

suction

and

discharge

service

valves.

Vent

re¬

maining

pressure

in

compressor

to

atmosphere.

2.

Add

oil

thru

oil

filler

connection.

3.

To

remove

oil,

remove

compressor

crankcase

oil

drain

plug.

Refer

to

Carrier

Standard

Service

Techniques

Manual,

Chapter

1,

for

complete

instructions

on

checking,

adding

or

removing

compressor

oil.

Cleaning

Coils

—

The

coils

can

be

cleaned

with

a

vacuum

cleaner,

washed

out

with

water,

blown

out

with

compressed

air,

or

brushed.

Fan

motors

are

drip

proof

but

not

waterproof.

TROUBLESHOOTING

GUIDE

COMPRESSOR

DOES

NOT

RUN

Contactor

Open

Power

off

—

restore

power.

Fuses

blown

—

replace

with

correct

fuses.

Control

circuit

breaker

open

-

check

for

short

circuit

in

control

wiring.

Transformer

dead

—

replace

transformer

if

primary

windings

are

receiving

power.

Thermostat

circuit

open

—

check

thermostat

setting.

Timer

motor

defective

—

replace

timer.

Compressor

lockout

circuit

open

—

check

for

excessive

compressor

current

draw

(140%

FLA

max

allowable)

or

excessive

motor

temperature

(motor

thermostat

opens).

After

corrective

action,

press

reset

button.

Low-pressure

switch

open

—

check

for

refrigerant

undercharge

or

obstruction

of

indoor

air

flow.

High-pressure

switch

open

—

check

for

refrigerant

overcharge

or

obstruction

of

outdoor

air

flow.

Connections

loose

—

tighten

all

connections.

Compressor

stuck

—

see

06D

service

literature.

Contactor

Closed

Compressor

leads

loose

—

check

connections.

Motor

windings

open

—

see

06D

compressor

service

literature.

Single

phasing

-

replace

blown

fuse.

Contactor

Closed

Then

Open

If

compressor

lockout

circuit

is

open

—

see

Contactor

Open.

If

compressor

lockout

circuit

is

closed

—

see

Compressor

Cycles

on

High-

(or

Low-)

Pressure

Switch.

COMPRESSOR

CYCLES

ON

HIGH-PRESSURE

SWITCH

Condenser

Fan

On

High-pressure

switch

faulty

—

replace

switch.

Air

flow

restricted

—

remove

obstruction.

Air

recirculating

—

clear

airflow

area.

Noncondensables

in

system

—

purge

and

recharge

as

required.

Refrigerant

overcharge

-

purge

as

required.

Line

voltage

incorrect

—

consult

power

company.

Refrigerant

system

restrictions

—

check

or

replace

filter-drier,

expansion

valve,

etc.

Condenser

Fan

Off

Fan

slips

on

shaft

—

tighten

fan

hub

setscrews.

Motor

not

running

—

check

power

and

capacitor.

Motor

bearings

stuck

—

replace

bearings.

Motor

overload

open

—

check

overload

rating.

Check

for

fan

blade

obstruction.

Motor

burned

out

—

replace

motor.

COMPRESSOR

CYCLES

ON

LOW-PRESSURE

SWITCH

Evaporator

Air

Fan

Running

Filter-drier

plugged

—

replace

filter-drier.

Expansion

valve

power

head

defective

—

replace

power

head.

Low

refrigerant

charge

—

add

charge.

Check

low-

pressure

switch

setting.

Air

Flow

Restricted

Coil

iced

up

—

check

refrigerant

charge.

Coil

dirty

—

clean

coil

fins.

Air

filter

dirty

—

clean

or

replace

filters.

Dampers

closed

—

check

damper

operation

and

position.

Evaporator

Air

Fan

Stopped

Electrical

connections

loose

—

tighten

all

connections.

Fan

relay

defective

—

replace

relay.

Motor

overload

open

—

power

supply.

Motor

defective

—

replace

motor.

Fan

belt

broken

or

slipping

—

replace

or

tighten

belt.

COMPRESSOR

RUNS

BUT

COOLING

INSUFFICIENT

Suction

Pressure

Low

Refrigerant

charge

low

—

add

refrigerant.

Low-pressure

switch

setting

too

high

—

adjust

to

correct

setting.

Head

pressure

low

—

check

refrigerant

charge.

Check

condenser

air

fan

thermostat

settings.

Air

filters

dirty

—

clean

or

replace

filters.

Expansion

valve

power

head

defective

—

replace

power

head.

Evaporator

coil

partially

iced

—

check

low-pressure

setting.

Evaporator

air

flow

restricted

—

remove

obstruction.

Suction

Pressure

High

Compressor

valves

defective

—

see

06D

service

literature.

Heat

load

excessive

—

check

for

open

doors

or

windows.

For

replacement

items

use

Carrier

Specified

Parts.

Manufacturer

reserves

the

right

to

discontinue,

or

change

at

any

time,

specifications

or

designs

without

notice

and

without

incurring

obligations.

Tab

4

Form

38AD-4SI

Supersedes

38AD-3SI

Printed

in

U.S.A

474

9-71

Codes

B

and

MS

Catalog

No.

533—824