MovinCool 24HFU Service Manual

SERVICE MANUAL

24HFU and 24HFU-1

DENSO SALES CALIFORNIA, INC.

REGISTERED TO ISO 9002

FILE NO. A5537

© 2000 DENSO SALES CALIFORNIA, INC.

All rights reserved. This book may not be reproduced or copied, in whole or in part, without the written permission
of the publisher. DENSO SALES CALIFORNIA, INC. reserves the right to make changes without prior notice.
MovinCool is a registerd trademark of DENSO CORPORATION.

DSCA P/N: LA990009-0205-E

[phone] www.movincool.com

FOREWORD

This manual has been published to service the MovinCool 24HFU and 24HFU-1. Both the Model 24HFU and
24HFU-1 perform the same basic function, however the 24HFU-1 has additional features. Please use this service
manual in servicing Models 24HFU and 24HFU-1.

DEFINITION OF TERMS

WARNING

Describes precautions that should be observed in order to prevent injury to the user during installation or
unit operation.

CAUTION

Describes precautions that should be observed in order to prevent damage to the unit or its components,
which may occur during installation or unit operation if sufficient care is not taken.

NOTE

Provides additional information that facilitates installation or unit operation.

GENERAL PRECAUTIONS

WARNINGS:

• All electrical work if necessary, should only be performed by qualified electrical personnel. Repair to
electrical components by non-certified technicians may result in personal injury and/or damage to the unit.
All electrical components replaced must be genuine MovinCool, purchased from an authorized reseller.

• When handling refrigerant, always wear proper eye protection and do not allow the refrigerant to come in
contact with your skin.

• Do not expose refrigerant to an open flame.

• The proper electrical outlet for MovinCool units must be equipped with a “UL” approved ground-fault
breaker to prevent electrical shock from the unit.

• When brazing any tubing, always wear eye protection and brazing tubing in a well ventilated area.

MOVINCOOL 24HFU / 24HFU-1 SERVICE PAGE 2

GENERAL DESCRIPTION

Generally speaking conventional air conditioners cool
the entire enclosed environment. They act as “heat
exchangers”, requiring an interior unit (evaporator) to
blow cool air into the interior and an exterior unit
(condenser) to exhaust exchanged heat to the out­doors. Unlike conventional air conditioners, the
MovinCool Spot Cooling System is a spot cooler which
directs cool air to particular areas or objects.
MovinCool Spot Cooling Systems have the following
features:

1-1. Compact Design

The innovative design of MovinCool has resulted
in one compact unit, replacing the need for two
separate units.

■ Conventional Air Conditioner

1-2. Easy Transportation and Installation

With the whole cooling system built into one
compact unit, MovinCool requires no piping and
can be easily transported and installed.

1-3. Energy Conservation

MovinCool is economical because it cools only
the area or objects which need to be cooled.

Air Flow of MovinCool Spot Cooling System

■

MOVINCOOL 24HFU / 24HFU-1 SERVICE PAGE 3

CONSTRUCTION AND SPECIFICATIONS

■ Construction of Models 24HFU & 24HFU-1

MOVINCOOL 24HFU / 24HFU-1 SERVICE PAGE 4

CONSTRUCTION AND SPECIFICATIONS

2-1. Basic Construction

The MovinCool Spot Cooling System is compact
in construction because the condenser and the
evaporator are enclosed in one unit. The interior
is divided into three sections. The upper front
face is equipped with the evaporator, while the
lower front face contains the drain tank. The
rear section contains the condenser, the com­pressor and the control box.

2-2. Air Flow

Air drawn from the right side face passes
through the condenser and extracts the heat.
This hot air is blown out through the upper
exhaust air duct. Air taken in from the front face
is cooled by the evaporator and then blown
through the cooling air duct which can be turned
in any direction. All the air inlets are provided
with filters, while the exhaust air duct is pro­tected by wire mesh.

■ Air Flow

2-3. Compressor and Fans

The compressor is hermetically sealed. One
motor is used with two centrifugal fans to draw
air across the evaporator and condenser.

2-4. Drain Tank

The capacity of the drain tank is 5.3 gallons (20
liters). The unit is equipped with a full tank lamp
and a device to automatically stop the unit’s
operation when the drain tank reaches a level of
approximately 4.4 ± 0.5 gallons (16.5 ± 2 liters).

MOVINCOOL 24HFU / 24HFU-1 SERVICE PAGE 5

CONSTRUCTION AND SPECIFICATIONS

ITEM/MODEL 24HFU 24HFU-1

[Rating Condition] DB 35˚C WB 28.2˚C DB 35˚C WB 28.2˚C

95˚F 83˚F 95˚F 83˚F

RH 60% RH 60%

[Features]

Power frequency___________ (Hz) 60 60
Line voltage ______________ (Volt) Single phase 230 Single phase 230
Power consumption ________ (Kw) 3.1 3.1
Current consumption _______ (Amp) 14.0 14.0
Power factor ______________ (%) 96 96
Starting current ____________ (Amp) 62 62
Power wiring ______________ (AWG) 12 (3-core) 12 (3-core)

[Cooling Unit]

Cooling capability __________ (Kcal/h) 6,000 6,000

________________________ (Btu/h) 24,000 24,000

Cooling system Direct expansion Direct expansion

[Blower]

Type of fan Centrifugal fan Centrifugal fan
Condenser - Air flow ________ (ft
Evaporator - Air flow ________ (ft3/min) 706 706
Motor output ______________ (Kw) 0.55 0.55

[Compressor]

Type Hermetic scroll Hermetic scroll
Output___________________ (Kw) 1.6 1.6
Refrigerant type R-22 R-22
Refrigerant amount _________ (kg) 0.85 0.85

________________________ (lbs) 1.87 1.87

[Safety Device]

Compressor overload relay With With
Fan motor protector With With
Drain switch With With
Anti-freezing thermostat With With
High pressure switch With With
Restart relay - power interruption Without With
Time delay relay Without With

[Dimensions and Weight]

W x D x H ________________ (mm) 490 x 730 x 1200 490 x 730 x 1200

________________________ (inch) 19.3 x 28.7 x 47.2 19.3 x 28.7 x 47.2

Weight___________________ (kg) 107 107

________________________ (lbs) 235 235

[Operating Conditions]

Intake air temperature range 45˚C (113˚F), RH ≤50% 45˚C (113˚F), RH ≤50%

[Control Device]

Temperature control Without With

3

/min) 1,200 1,200

to 25˚C (77˚F), RH ≥50% to 25˚C (77˚F), RH ≥50%

■ Specifications

MOVINCOOL 24HFU / 24HFU-1 SERVICE PAGE 6

Specifications are subject to change without notice.

REFRIGERANT SYSTEM

The component parts of the refrigerant system include the following:

• Compressor • Evaporator

• Condenser • High pressure switch

• Capillary tube • Modulating tank

These parts are all connected by copper piping. All the connections have been brazed.

Condenser

Compressor

Modulating Tank

Evaporator

Capillary T ube

High Pressure Switch

■ Refrigerant System

MOVINCOOL 24HFU / 24HFU-1 SERVICE PAGE 7

REFRIGERANT SYSTEM

3-1. Compressor

The compressor used for the unit is hermetically sealed. The compressor and the compressor motor are in
one casing.

3-1-1. Compressor Theory of Operation

The scroll utilizes an involute spiral which, when matched with a mating scroll form, generates a
series of crescent-shaped gas pockets between the two members. During compression, one scroll
remains stationary (fixed scroll) while the other form (orbiting scroll) is allowed to orbit (but not rotate)
around the first form. As this motion occurs, the pockets between the two forms are slowly pushed to
the center of the two scrolls while simultaneously being reduced in volume. When the pocket reaches
the center of the scroll form, the gas, which is now at a high pressure, is discharged out of a port
located at the center. During compression, several pockets are being compressed simultaneously,
resulting in a very smooth process. Both the suction process (outer portion of the scroll members)
and the discharge process (inner portion) are continuous.

3-1-2. Compressor Operation

1) Compression in the scroll is created
by the interaction of an orbiting spiral
and a stationary spiral. Gas enters
the outer openings as one of the
spirals orbits.

2) The open passages are sealed off as
gas is drawn into the spiral.

3) As the spiral continues to orbit, the
gas is compressed into two increas­ingly smaller pockets.

MOVINCOOL 24HFU / 24HFU-1 SERVICE PAGE 8

REFRIGERANT SYSTEM

4) By the time the gas arrives at the
center port, discharge pressure has
been reached.

5) Actually, during operation, all six gas
passages are in various stages of
compression at all times, resulting in
nearly continuous suction and dis­charge.

NOTE

Upon compressor shut-off, the compressor may
run backward for a moment or two until internal
pressures equalize. This has no effect on com­pressor durability but may cause an unexpected
sound after the compressor is turned off and
should not be diagnosed as a malfunction.

3-2. Condenser

The condenser is a heat exchanger whose
copper tubes are covered with thin aluminum
projections called spine fins. Heat is given off
and absorbed by air being pulled across the
condenser fins by the centrifugal fan and then
expelled through the exhaust air duct.

MOVINCOOL 24HFU / 24HFU-1 SERVICE PAGE 9

REFRIGERANT SYSTEM

3-3. Capillary Tube

The capillary tube is a long thin tube and its line
flow resistance serves as an expansion valve.
The length and the inner diameter of the capil­lary tube are determined according to the
capacity of refrigeration system, operating
conditions and the amount of refrigerant.
The capillary tube causes the high pressure,
high temperature liquid refrigerant sent from the
condenser to expand rapidly as the refrigerant is
sprayed out through the fixed orifice in the
capillary tube. As a result, the temperature and
state of the refrigerant become low and mist­like, and therefore it evaporates easily.

Capillary Tube Dimensions

Qty Purpose of Use I.D. (mm) Length (mm)

1 For cooling ∅1.5 ± 0.05 540

3-4. Evaporator

The evaporator, like the condenser, is a heat
exchanger covered with spine fins. Heat is
removed from the air being pulled across the
evaporator by the centrifugal fan and the
resulting cool air is expelled through the cooling
air ducts.

■ Capillary Tube

3-5. Modulating Tank

The modulating tank consists of a copper pipe
and tank sections, each being separated from
the other. The pipe connects to the evaporator
outlet at one end and to the compressor at the
other; the tank connects to the evaporator inlet.
The modulating tank is covered with insulation to
reduce thermal effects of ambient temperature.
It varies the quantity of refrigerant in the refriger­ating cycle for optimum operating condition; it
stores part of refrigerant under light load and
delivers additional refrigerant to the cycle under
heavy load.

3-6. High Pressure Switch

The high pressure switch prevents the con­denser and compressor from being damaged by
excessively high pressure in the high pressure
line of the refrigeration cycle. The switch is
normally closed. The snap disk responds to
variations in pressure and, if pressure is abnor­mally high, the snap disk moves down to push
the pin down, causing the internal contacts to
open. This generates a signal to open the
auxiliary relay.
Possible causes of this trouble include:

(1) The condenser air filter is dirty, restricting

air flow.

(2) The condenser blower is defective.

■ Modulating Tank

■ High Pressure Switch

MOVINCOOL 24HFU / 24HFU-1 SERVICE PAGE 10

REFRIGERANT SYSTEM

Condenser
Inlet Pipe

Compressor
Discharge
Pipe

Condenser
Outlet Pipe

Compressor Suction
Pipe (insulated)

Evaporator
Inlet Pipe

Evaporator
Outlet Pipe

Capillary T ube

Connecting Pipe
(evaporator to compressor)

Connecting Tube
(condenser to capillary tube)

■ Refrigerant System Piping

MOVINCOOL 24HFU / 24HFU-1 SERVICE PAGE 11

ELECTRICAL SYSTEM • 24HFU

24HFU

■ Electrical System and Control Box for Model 24HFU

MOVINCOOL 24HFU / 24HFU-1 SERVICE PAGE 12

ELECTRICAL SYSTEM • 24HFU

4-1. Basic Operation of MovinCool Modelp 24HFU Electrical Circuit

The three basic modes of operation are as follows:

■ Operation in “OFF” position

2) Control Switch in “FAN” position:
a. Current also flows through the control

switch (CS) to the fan motor (MF).

b. Current flows through the contact (termi-

nals 19 and 20) of the auxiliary relay and
its coil, and remains closed.

1) Control Switch in “OFF” position:
a. Current flows through terminals 5 and 2

of the control switch (CS) and to the coil
of the auxiliary relay (RX). (A and B.)

b. Two contacts (RX) of the auxiliary relay

are closed by electromagnetic force. The
closed contact RX (terminals 19 and 20)
allows current to flow directly to the
auxiliary relay coil and hold the contact in
a closed position.

NOTE

Symbol indicates alternating current.

■ Operation in “FAN” position

■ Operation in “COOL” position

3) Control Switch in “COOL” position:
a. The contacts of the auxiliary relay remain

closed as mentioned in step 2) b.
b. Current flows to the fan motor (MF).
c. Current also flows to the anti-freezing

thermostat (THS) contact, to the coil of

the relay for the compressor motor

(MCC) (A and B) and the auxiliary relay

contacts.
d. Two contacts of the relay for the com-

pressor motor (MCC) are closed by the

electromagnetic force. Current then

flows to the compressor motor (MC).

MOVINCOOL 24HFU / 24HFU-1 SERVICE PAGE 13

ELECTRICAL SYSTEM • 24HFU

4-2. Control Box

4-2-1. Capacitor

The capacitor is used to boost power
output to the fan motor and the compres­sor at start-up.
The specifications of each capacitor are
shown below.

Capacitor Registrant Voltage Capacitance

(Volt) (mF)
For fan motor 440 12.5
For compressor 370 40

4-2-2. Auxiliary Relay

This auxiliary relay is normally closed
when the unit is in operation (FAN or
COOL), and supplies power to the com­pressor relay and the fan motor. In the
following cases, however, the relay opens
to interrupt power to the compressor and
the fan motor.

• When the drain tank is filled with water.
(Drain switch OFF.)

• When the high pressure becomes
excessively high. (High pressure switch
OFF.)

When current flows across A and B,
terminals 11 and 12, 13 and 14, 15 and
16, 19 and 20 conduct.

■ Circuit of Auxiliary Relay

■ Auxiliary Relay

Specifications:

Rated Voltage AC 240V
Rated current 15 amps
UL Listed File No. E1 12482

4-2-3. Compressor Relay

The compressor relay is closed when the
unit is operating in COOL mode, and
supplies power to the compressor. How­ever in the following cases, the relay
opens to cut off power to the compressor.

• When the auxiliary relay is opened.
(Drain switch OFF or high pressure
switch OFF.)

• When the evaporator has frosted.
(Thermostat OFF.)

Specifications:

Rated Voltage AC 230V
Rated Current 30 amps
UL Listed File No. E43028

■ Circuit of Compressor Relay

■ Compressor Relay

MOVINCOOL 24HFU / 24HFU-1 SERVICE PAGE 14

■ Control Switch

■ Fan Motor

CF1
CF2
RX12

ELECTRICAL SYSTEM • 24HFU

4-3. Control Switch

The control switch is employed to start or stop
operation. This switch is a 250V, 20A rating
rotary type (3-position). The switching positions
are OFF-FAN-COOL. Each contact is switched
by the cam uniting with the shaft.

Switch Terminals OFF FAN COOL

(5) - (2) Conduct OFF OFF
(5) - (1) OFF Conduct OFF
(5) - (4) OFF Conduct Conduct

4-4. Fan Motor

The fan motor is a single phase, induction type
motor which drives fans on the evaporator side
and the condenser side at the same time.

Specifications:

Rated Voltage AC 230V
Rated Output 552 Watts
UL Listed File No. E49807

4-5. Compressor Motor

The compressor motor is a single phase motor
and is contained within the same housing as the
compressor.

Specifications:

Rated Voltage AC 230V
Rated Output 1600 Watts

■ Thermostat

NOTE

An internal overload relay is used to protect the
compressor motor and fan motor. This relay is
built into the compressor motor and fan motor and
will interrupt the flow of current when there is an
overcurrent situation or if abnormally high
temperature builds up in the compressor motor or
fan motor.

4-6. Anti-freezing Thermostat

If the evaporator has frosted, the thermostat
contacts open to stop the compressor and the
unit continues to operate on “FAN” mode. Once
the evaporator has defrosted, the contacts close
to restart the compressor and the unit operates
in “COOL” mode. The thermostat heat sensing
tube is mounted at the evaporator outlet tube
and is insulated from surrounding air by heat
insulating material. The thermostat contacts are
opened at -1.5˚C and closed at +14.5˚C.

MOVINCOOL 24HFU / 24HFU-1 SERVICE PAGE 15