AIR CONDITIONER

OVERHAUL MANUAL

Subject part No. Subject model Applicable

serial No.
709-82700001 HD513MR From first
709-82700001 HD820II From first

805181E
 Introduction (5151-001-0E)

This book is the procedure manual concerning disassembly and assembly and inspection of pneumatic and hydraulic
parts (units) and main equipment (assembly parts).
When disassembling applicable parts observe the precautions below and work according to this manual.

1. When disassembling hydraulic machinery aim for cleanliness, order and good management.
Particularly when detaching and handling heavy objects from the main body of the machine use a suitable crane
or hoist winch.
When disassembling and assembling use the specified jigs and tools and the regulation torque control.

2. Refer to the “Service Manual” for the procedure when removing and reattaching applicable parts from the main
body of the machine.

3. Always refer to the applicable parts list when replacing parts.

4. When the reassembly of applicable parts is finished, test them as separate units before reattaching to the main
body of the machine.

5. For the test after reattachment, first carry out preoperational checks then operate unloaded.

(5181-001-0E)

1 Specifications ································································································ 1

2 Summary of the air conditioner with automatic

climate control ······························································································· 3
3 System composition ·················································································· 4

4 Control parameters when in the AUTO mode ····························· 5

5 Operation procedure ················································································· 6

6 Controls other than for temperature ················································ 8

7 Display and control during malfunctions ······································ 9

8 Monitor mode ······························································································· 10

9 Structure diagram ····················································································· 15

805181E
10 Refrigerant charging method ····························································· 19

11 Troubleshooting ························································································· 25

12 Electrical circuit diagram ······································································· 31

A C TUK-R104S E
B 709-82700001 D 200003 (TG) F
1. Specifications (5181-002-0E)

Type
Item
Air conditioner with automatic climate control (heating/cooling
Air conditioner type single unit)
Cooling capacity 4.30kW 10% (3700kcal/h 10%)
Heating capacity 5.23kW 10% (4500kcal/h 10%)
Model SD7H15WL7992
Compression method 7 cylinder reciprocating
Compressor Displacement Cylinder volume: 154.9 cc/rev
Compressor oil SP20: 240 cc 10 cc
Voltage 24V
Power consumption 34W
Magnetic clutch
Pulley - Pulley ratio Pulley outer diameter: 146mm

Type Serpentine (aluminum)

Evapo- Dimensions 217 251 106 (H W D)

rator Expansion
Internal equalizing type 1.2R ton
valve
Type ———
Heater
Dimensions 207 250 68 (H W D)
Air conditioner Type Single inlet centrifugal type
unit
Air flow 430m3/h 10% (FECE mode) when cooling
Blower volume 310m3/h 10% (FOOT mode) when heating
Voltage - Fixed voltage rating: DC 27V
Power con- Power consumption: 160W (at DC 24V)
sumption
Intake source Internal air, Outside air
Outlet direction FACE, FOOT, DEF
Layout Tandem
Condenser Type Serpentine
Dimensions 396 440 40 (H W D)
Type Single unit (with sight glass and high-low pressure switch)
Receiver drier
Desiccant Molecular sieves (XH-9)
High-low pressure Internally nylon coated hybrid hose (with aluminum hardware
Tubing system liquid lines on both ends) (S hoses are not internally coated with nylon)

—1—
 Type
Item
Type Computerized (automatic)
Temperature Automatic hot water flow regulation
Air flow volume 4 level automatic, 3 level manual
Air outlet FACE, FACE & FOOT, FOOT, DEF
Control Control Intake/
recirculation Recirculate internal air, Intake outside air
switching
Seat switch configuration (180 50), LED display, includes
Control panel
night illumination
Defrosting method Air thermal

High- High pressure OFF: 3.14 0.2MPa (32 2kgf/cm2)

low DIFF: 0.6 0.2MPa (6 2kgf/cm2)
Protective pressure OFF: 0.196 0.02MPa (2.0 2kgf/cm2)
systems switch Low pressure DIFF: 0.03MPa or less (0.3kgf/cm2 or less)
Open valve pressure: 3.52MPa (35.7kgf/cm2) 4.1MPa
Relief valve (41.8kgf/cm2)
Close valve pressure: 3.01MPa (30.7kgf/cm2) or more
Refrigerant HFC-134a

* 1. Requirements (for cooling)

Dry bulb temperature for intake air: 27.0 1.0
Wet bulb temperature for intake air: 19.5 0.5
Refrigerant pressure before expansion valve: 16.7kgf/cm2
Undercooling degree of refrigerant before expansion valve: 5.0 degrees
Evaporator outlet refrigerant pressure: 1.59kgf/cm2
Motor terminal voltage: DC 27V
Vent resistance (FACE mode): 20mmq
Air conditioner air flow volume: 430m3/h 10%

2. Requirements (for heating) in accordance with JIS D5901-1988

Intake air: 20
Hot water temperature: 85
Hot water flow volume: 6.0 l/h 10%
Air flow volume: 310m /h3
10%

—2—
2. Summary of the air conditioner with automatic climate
control (5181-003-0E)

This air conditioner with automatic climate control (automatic air conditioner hereafter) can automatically maintain
a comfortable operation cab environment throughout all seasons, without requiring the operator to use troublesome
controls.
The distinguishing difference between this unit and a manual air conditioner is that it works to make the operation
cab temperature the same as the target temperature setting.
Therefore, compared to a manual air conditioner, where the air outlet temperature is adjusted by the operator
adjusting the controls, the automatic air conditioner automatically controls the air conditioner so the air outlet
temperature is at the target temperature.
On the other hand, using the automatic air conditioner, it is not possible to change or fix the air outlet temperature
freely to the operator’s desired level, like it is with a manual system. However, as with standard automatic air
conditioners, when this air conditioner is set to 18 (max. cooling) the air outlet temperature will be at minimum
and when it is set to 32 (max. heating) the air outlet temperature will be at maximum.

(1) Interior unit

This air conditioner is based on the manual air conditioner unit, with the addition or modification of required
microcomputer equipped controller parts etc.
Therefore, except for parts relating to the automatic control system, most parts can be maintained using the
same service procedures as for the previous units.
(2) Air outlet temperature control
The system is an automatic hot water flow regulation type system, which uses the same hot water flow
regulator valve as for the manual air conditioner to control the volume of engine coolant flowing through the
heater core and thereby control how much the passing air is heated.
Even at a particular value opening amount, the hot water flow volume will vary depending on engine speed.
Therefore, in order to accurately attain the target air outlet temperature, a sensor is located at the unit air outlet
opening, the measured temperature is fed back and the hot water flow regulator valve opening level is
adjusted.
(3) Air flow volume control
The operator can select either manual or automatic control, where the manual mode has 3 air flow levels and
the automatic mode has 4 air flow levels.
(4) If any of the sensors or the motor actuator for the hot water flow regulator valve has malfunctioned, the
decimal fraction of the temperature setting display will show an E, which indicates both that there is something
wrong and that the temperature setting step size accuracy has been decreased from 0.5 to 1 .
In addition, if the internal air temperature sensor has malfunctioned, all AUTO control functions are deactivated
and it can be operated the same as a manual air conditioner.

—3—
3. System composition (5181-004-0E)

(1) System composition summary diagram

Cab Evaporation sensor

Air outlet sensor
Internal air
Heater core temperature
Solar radiation sensor sensor Outside air
temperature sensor

Blower motor

Evaporator

Engine coolant
Condenser

Water temperature Hot water flow

sensor regulator valve Compressor
5181-001E-0

(2) Parts for the automatic air conditioner

This automatic air conditioner has added or modified primarily the following functional parts, with respect to
a manual air conditioner.
Modifications
• Controller: It controls all air conditioner functions, except for night illumination.
• Control panel: It selects and displays air conditioner functions in response to control inputs from the operator.
• Resistor: The coil resistor of the manual air conditioner has been replaced with a flat resistor.
This allows increasing the air flow volume levels from 3 to 4.
Additions
• Internal air temperature sensor: This detects the temperature inside the operation cab. The output value is
used by the cab temperature control system.
• Outside air temperature sensor: This detects the outside air temperature. The output value is used by the
cab temperature control system.
• Water temperature sensor: This detects the engine coolant temperature. This is used to prevent cold
air from being discharged during startup.
• Solar radiation sensor: This detects the amount of sunlight. The output value is used by the cab
temperature control system.
Note The evaporation sensor is the same as for the manual air conditioner and used for the same purpose.
It is not used especially for the automatic air conditioner system.
Note The motor actuator is the same as for the manual air conditioner (see below).
• For the hot water flow regulator valve: 1 unit
• For the outlet mode (FACE-FOOT): 1 unit
• For the outlet mode (FOOT-DEF): 1 unit
• For switching between RECIRC (recirculation) and FRESH (intake): 1 unit

—4—
4. Control parameters when in the AUTO mode (5181-005-0E)

The block diagram below shows a summary of control parameters for this air conditioner when in the AUTO
mode.
Microcomputer equipped controller
Temperature
Air outlet temperature control
setting (Target Tset Air outlet temperature con-
cab temperature) Calculate Calculate how far hot water trol device (depends on
flow regulator valve should be hot water flow regulator
target air outlet valve and motor actuator)
open
Outside air tem- temperature
perature sensor

Solar radiation Calculate how much to

store in RAM memory

sensor adjust hot water flow

regulator valve opening
A/C switch Compressor clutch control
Compressor clutch
Internal air tempera- control device (depends
ture sensor Calculate target air outlet on relay)
temperature/air outlet sensor
Air outlet sensor input value
Blower motor speed switching
AD change

Clutch ON/OFF state control

Evaporation decision Blower motor speed
sensor Cold air discharge Air flow switching control device
prevention deci- speed deci- (depends on relay and re-
Water temperature sion sion sistor)
sensor

(1) Air outlet temperature control (if temperature setting is 18.5 ~ 31.5 )
First, values from the internal air temperature, outside air temperature and solar radiation sensors, and the
temperature setting (target cab temperature) set by the operator are used to determine a target air outlet
temperature.
At this point, the primary basis for determining the target air outlet temperature is the outside air temperature
and solar radiation sensor values, but in order to compensate for the difference between the set temperature
and the internal air temperature values, a proportional value of that difference is factored into the target
temperature. In addition, this proportional value is necessary for quickly approaching the set temperature level
when starting the air conditioner and when changing the temperature setting.
Next, in order that the air outlet sensor value matches the target air outlet temperature, the amount to open the
hot water flow regulator valve is decided and the motor actuator is activated to move the hot water flow
regulator valve to the determined opening level.
(2) Compressor control
When the compressor control is ON, the compressor clutch is turned ON/OFF depending on the evaporation
sensor value. This is to prevent icing in the evaporator and has nothing to do with controlling the air outlet
temperature.
(3) AUTO air volume control
The air flow volume is controlled by using the target air outlet temperature to decide what the blower motor
speed should be, or in other words, the air flow volume. Then a relay is switched to change the resistance
value of the resistor.
Air volume
H
M2
M1
L

Target air outlet temperature 5181-002E-0

The air volume control process also includes a separate cold air discharge prevention control, but that will be
explained later.
—5—
5. Operation procedure (5181-006-0E)

The following outlines how to operate the controls.

(1) Part names of the control panel
Air volume switching (display)
Air outlet switching
Air volume
FACE FACE FOOT DEF switching Compressor control
& Temperature (switch)
FOOT setting (display) Manual UP AUTO control

RECIRC FRESH DOWN UP Air volume Main ON/OFF switch

Intake/recirculation Temperature setting switching (switch)
Manual DOWN 5181-003E-0
switching (switch)

1) are all switch sections.

2) and are all LED display sections.
3) The LED color is orange for only the main switch and light green for all the others.
4) Switches and lettering sections are provided with night illumination with lighting LEDs, except for , ,
and .
(2) Basic operations
The basic operations for taking advantage of the automatic air conditioner functions are explained below.
1) Turn the main power switch ON and press the AUTO control switch to set the air flow volume to AUTO
control (press the A/C switch, as necessary), then set the temperature to the desired setting between 18.5
and 31.5 . Now the air conditioner outlet temperature and air flow volume will be automatically adjusted
so that the temperature inside the operation cab will approach the temperature setting.
2) The air outlet mode and air source is not switched automatically, so select the appropriate mode manually.
3) The desired temperature within the operation cab can be achieved by raising or lowering the temperature
setting.
4) If the air flow volume set by the AUTO control is not the desired level, set the air volume manually with
the air volume switch.
(3) How each section of the control panel functions
CAUTION
The cab temperature control system assumes air volume is being controlled
automatically, so after the air volume has been manually set, the temperature control
will be less accurate.

1) Main power source display and switch

• The LED display section will be lit when the air conditioner is in operation. When the air conditioner is not
in operation, this LED, along with all the other LEDs on the control panel will be off.
• When this switch is pressed, all the air conditioner functions will go ON or go OFF.
Each time the switch is pressed, it will toggle between ON and OFF.
When turned ON, it will start operating with the same settings that were active just before turning it OFF.
• If the starter switch (ACC switch) for the hydraulic excavator is turned OFF, the air conditioner operation
will be turned OFF.
2) AUTO control display and switch
• The LED display section will be lit when the air flow mode is AUTO control.
• When this switch is pressed, the air flow mode will be set to AUTO control and the LED will light.
• When the main power switch is OFF and this switch is pressed ON, the air conditioner functions will go
ON, just as though the main power switch had been pressed.
—6—
3) Temperature setting display and switches
• The temperature setting will be digitally displayed (lit by LED) in the display section.
The temperature setting range is 18.0 ~ 32.0 .
• In order to change the temperature setting press the DOWN or UP switch.
DOWN will lower it in steps of 0.5 and UP will raise it in steps of 0.5 .
If you keep the switch pressed, the temperature setting can be raised in multiple steps or lowered in
multiple steps.
• At a temperature setting of 18.0 the air conditioner will be set to its maximum cooling mode [COOL-
MAX control] and at 32.0 heating will be maximum [HOT-MAX control]. In either case, the temperature
setting will no longer function as the target cab temperature.
4) Air outlet mode display and switches
• The LED display for the active outlet mode will be lit.
• If one of the 4 mode switches is pressed, the corresponding outlet mode will be activated.
5) Intake/recirculation switching display and switches
• The LED display for the active air intake mode will be lit.
• If either the RECIRC (recirculate internal air) or FRESH (intake outside air) switches are pressed, the
corresponding air intake source mode will be activated.
6) Compressor control display and switch
• The LED display section will light when the compressor control is ON and turn off when OFF.
• Press this switch when turning the compressor control ON or OFF.
If the switch is pressed when the compressor control is OFF, it will go ON and the LED will light. If it is
pressed when it is ON, it will go OFF and the LED will turn off.
7) Air volume switching display and switches
(There are 4 air flow volume levels: L, M1, M2 and H. For AUTO control air flow volume levels refer to
the figure in section 4-(3).)
• The LED display section will show the current air flow mode, regardless of whether it is in the manual air
flow volume selection mode or AUTO air flow volume control mode.
Relationship between LED lighting and air flow volume is shown in Table 1. Table 1
LED lighting All off I
Air flow volume 0 (none) L M1 or M2 H
• Press the manual UP or manual Down switch to freely select the air flow volume.
After selecting the air flow volume it will remain fixed until the AUTO switch is pressed.
The selected air flow volume will be indicated by LED lighting on the air volume switching display, as
shown in Table 2. Table 2
LED lighting Switch Selected (fixed) air flow volume LED lighting after selecting
UP H
DOWN M1
UP H
DOWN L
UP M1
DOWN L

CAUTION
Air flow mode M2 cannot be selected manually.

• By pressing the manual UP or manual DOWN switch, the air flow volume AUTO control mode will be
disabled and the AUTO control LED will turn off.

—7—
6. Controls other than for temperature (5181-007-0E)

The following explains those other controls that do not directly relate to controlling the cab temperature.
(1) COOL-MAX and HOT-MAX controls
When the temperature setting is set to 18.0 or 32.0 , the COOL-MAX control mode or HOT-MAX
control mode will be activated respectively, and it will no longer control the cab temperature to approach the
set temperature.
Even during COOL-MAX or HOT-MAX control modes, all switches will function.
If the temperature setting is set within 18.5 ~ 31.5 , the COOL-MAX or HOT-MAX control mode will end
and return to the settings prior to starting that mode, ignoring any changes or operations made while in that
mode.
1) COOL-MAX control mode
• Hot water flow regulator valve: Completely closed
• Air flow volume: H
• Compressor control: ON
• Air outlet mode: FACE
2) HOT-MAX control mode
• Hot water flow regulator valve: Fully open
• Air flow volume: M2
• Compressor control: OFF
• Air outlet mode: FOOT

(2) Cold air discharge prevention control

During periods when the outside air temperatures are low, the coolant in the engine just after startup is cold,
so if air is immediately discharged into the cab the outlet air will be cold. In those cases, the air conditioner
will wait until the engine coolant temperature rises or will operate at a low air flow volume level.
1) Preconditions for activating the cold air discharge prevention control mode
• Air flow volume control: AUTO
• Target air outlet temperature – temperature setting 45
• Temperature setting: 18.5 ~ 31.5
• Air outlet mode: Other than DEF
• Time: Within 10 minutes after turning the hydraulic excavator starter switch ON.
2) Cold air discharge prevention control
• Water temperature sensor value is less than 20 : Air flow volume 0 (blower motor off) and compressor
control is OFF.
• Water temperature sensor value is 20 ~ 35 : Air flow volume L
• Water temperature sensor value is more than 35 : AUTO air flow volume control
Under this control mode, the air flow mode can change from 0 to L or L to AUTO, but will not change from
AUTO to L or L to 0. However, this control mode can be canceled by turning the hydraulic excavator starter
switch OFF and then turning it ON, which will reinitialize the control mode again.

—8—
7. Display and control during malfunctions (5181-008-0E)

When any of the sensors for this air conditioner, except the solar radiation sensor, or the motor actuator has a
particular malfunction, it is indicated on the control panel and control changes to the malfunction mode.

(1) When a malfunction is indicated on the temperature setting display

It can be one of the following three types.
Multiple sensors have malfunctioned, including the internal air temperature sensor (where
HL.*
* is a number from 0 ~ 9).
All AUTO control functions are deactivated and the outlet air is heated in proportion to the
number * on the temperature setting switch.
(This is equivalent to manual operation. In other words, all the air outlet temperature, air
flow volume and compressor control functions are selected manually.)

**.E A sensor other than the internal air temperature sensor and solar radiation sensor has
malfunctioned, or the motor actuator has malfunctioned (where ** is a number from 18 ~
32).
The temperature setting can be increased or decreased by 1 and the control system
does not use the problem sensor or actuator.
(For example, if the evaporation sensor has malfunctioned, the compressor control can no
longer be turned ON.)
HL.E The internal air temperature sensor has malfunctioned in conjunction with the motor
actuator for the hot water flow regulator valve. All AUTO control functions are deactivated.
It is no longer possible to adjust how much the outlet air is heated or the temperature
setting.

(2) When a malfunction is indicated on the mode selection indicator

When a motor actuator, other than the hot water flow regulator valve is locked, or there is a break in a
circuit, the motor actuator operation is stopped or limited and the LED that corresponds to the mode where
selection switching has malfunctioned will flash.

Ex.) If it locks while switching the air source modes from FRESH (intake) to RECIRC (recirculation), it will
be reverted to and kept at FRESH, and the LED display section for RECIRC will flash. Thereafter, until
the air conditioner is turned OFF, the RECIRC switch will not accept input.

—9—
8. Monitor mode (5181-009-0E)

The monitor mode is for analyzing the controller itself or other malfunctions etc.
If the control panel receives special switch inputs indicated below, it will use the monitor mode.

(1) Starting the monitor mode

When the air conditioner is being operated under the primary control system and the RECIRC or FRESH
switch circuit is being closed, if the main switch circuit on the control panel is closed for 5 seconds, the
monitor mode will start.

(2) Monitor process

1) Diagnosis of each LED segment:Once in the monitor mode, all LEDs (except night illumination) will light
for 5 seconds.
The LED in a broken circuit will not light.
2) Sensor diagnosis: If there is a break or short in a circuit, it will indicate which it is.
3) Motor actuator diagnosis: For each of the actuators, it will indicate whether there is a locked motor,
or a short or break in the potentiometer circuit.

CAUTION
The circuits that can be diagnosed for shorts depend on section 6. (1)-2).

(3) Panel operations and displays during monitor mode

1) Air outlet mode: This is used for selecting the monitor process.
Using the 2 switches for FACE and DEF modes, the 4 LEDs for FACE, FACE & FOOT,
FOOT and DEF are turned on or off in certain combinations and the monitor process is
selected.
2) FRESH/RECIRC (Intake/recirculation) switching: This is used for selecting the monitor process.
Using the 2 switches for RECIRC and FRESH, the LED
for either RECIRC or FRESH is lit and the monitor
process is selected.

(4) Air conditioner functions during monitor mode

Once in the monitor mode, all control functions will stop and, until canceled, all switches will be disabled for
normal air conditioner operations and changing settings.

(5) Canceling the monitor mode

When in the monitor mode, if while the RECIRC or FRESH switch circuit is being closed, the main switch
circuit on the control panel is closed for 5 seconds, the monitor mode will be canceled and it will revert to the
primary control mode.
In addition, turning the hydraulic excavator starter switch OFF will have the same result.

— 10 —
(6) Sensor diagnosis
1) Sensor malfunction display
If the air source mode (FRESH/RECIRC) switching display light and the air outlet mode display light are
combined in the following way, the temperature setting display section will show whether there is any
malfunction (a short or broken circuit) in any of the sensor circuits.
The following section (6)-2) can be used to determine whether a malfunction is a short or broken circuit.

Air source mode (FRESH/RECIRC) Air outlet mode display

switching display
RECIRC FRESH FACE FACE&FOOT FOOT DEF

indicates LED is lit and indicates LED is not lit.

CAUTION
Detection of sensor malfunctions can be performed either during air conditioner
operation or during the test mode. Once a malfunction is detected, even if that
location returns to normal the detection of a malfunction will not be canceled. Either
turn the hydraulic excavator starter switch OFF or turn the air conditioner off using
the main switch on the control panel in order to cancel the malfunction detection
state.

Relationship between the malfunctioning sensor and the temperature setting display section (“ ” indicates a
malfunction.)

— 11 —
2) Sensor input value display
Select a sensor by a combination of the air source mode (FRESH/RECIRC) switching display light and the
air outlet mode display light, then each sensor output value can be displayed in the temperature setting
display section.

CAUTION
1. The displayed “hexadecimal data” is the actual data at that time.
For example, if a malfunction is detected and a sensor malfunction is displayed, if
that location returns to normal the indicated value will no longer be in the range it
was during the malfunction.
2. The sensor output value ( ) data displayed when operating normally is actual
current data, but actual data will not be displayed during a malfunction.

— 12 —
(7) Motor actuator diagnosis

CAUTION
1. Detection of motor actuator malfunctions is only performed while the air conditioner
is operating and is not performed during the test mode. Therefore, even if the
potentiometer circuit malfunctions during the test mode, a malfunction will not be
displayed.
2. Once a malfunction is detected, even if that location returns to normal the detection
of a malfunction will not be canceled. Either turn the hydraulic excavator starter
switch OFF or turn the air conditioner off using the main switch on the control
panel in order to cancel the malfunction detection state.

1) Motor actuator malfunction display

If the air source mode (FRESH/RECIRC) switching display light and the air outlet mode display light are
combined in the following way, the temperature setting display section will show whether there is any
malfunction related to any motor actuator.
The following section (7)-2) can be used to confirm what the malfunction is.

Relationship between the malfunctioning motor actuator and the temperature setting display section (“ ”
indicates a malfunction.)
Temperature setting display section E00 E10 E20 E30 E40 E50 E60 E70
Air outlet mode (FACE-FOOT)
Air outlet mode (FOOT-DEF)
Air source mode (FRESH/RECIRC) switching
Hot water flow regulator valve
Temperature setting display section E80 E90 EA0 EB0 EC0 ED0 EE0 EF0
Air outlet mode (FACE-FOOT)
Air outlet mode (FOOT-DEF)
Air source mode (FRESH/RECIRC) switching
Hot water flow regulator valve

— 13 —
 2) Hot water flow regulator valve and air outlet mode (FACE-FOOT) motor actuator malfunction explanation
display
If the air source mode (FRESH/RECIRC) switching display light and the air outlet mode display light are
combined in the following way, the temperature setting display section will show whether there is any
malfunction related to any motor actuator.

Temperature
setting display X value: Displays an explanation of malfunctions for the hot water flow regulator valve motor
E X Y actuator.
Y value: Displays an explanation of malfunctions for the air outlet mode (FACE-FOOT) motor
actuator.
Relationship between what is displayed at the temperature setting display section and what the malfunction
is (“ ” indicates a malfunction.)

3) Air outlet mode (FOOT-DEF) and air source mode (FRESH/RECIRC) switching motor actuator malfunction
explanation display
If the air source mode (FRESH/RECIRC) switching display light and the air outlet mode display light are
combined in the following way, the temperature setting display section will show whether there is any
malfunction related to any motor actuator.

Temperature
setting display X value: Displays an explanation of malfunctions for the air outlet mode (FOOT-DEF) motor
E X Y actuator.
Y value: Displays an explanation of malfunctions for the air source mode (FRESH/RECIRC)
switching motor actuator.
Relationship between what is displayed at the temperature setting display section and what the malfunction
is (“ ” indicates a malfunction.)
Displayed X or Y value 0 4 C Values for 1, 2, 3, 5, 6, 7, A, B,
Explanation of Motor lock (when rotating normally) D, E and F are not displayed.
malfunction Motor lock (when rotating in reverse)

— 14 —
9. Structure diagram (5181-010-0E)

Compressor Air conditioner unit

Control panel

Condenser Internal air filter

Outside air filter

Receiver drier
(with sight glass and high-low pressure
switch)

5181-004E-0

Automatic air
conditioner controller
Evaporation sensor
Internal air filter
FACE
outlet Internal air intake
Evaporator
Damper (FACE-FOOT)

FACE-FOOT
damper motor

Resistor

Air outlet sensor

Water valve (hot
water valve) motor

Water valve (hot

water valve)

Blower motor Water temperature sensor

FACE FOOT outlet for heater

FOOT-DEF
damper motor 5181-005E-0
DEF outlet
Damper (FOOT-DEF)
Evaporator
FOOT

REC

DEF

Blower Heater
FRE
5181-006E-0

— 15 —
 5181-007E-0

— 16 —
Ref. No. Part name Q’ty Ref. No. Part name Q’ty
1 Evaporator assembly 1 34 Clamp 1
2 Intake case (lower) 1 35 Clamp 1
3 Evaporator case (upper) 1 36 Blower motor 1
4 Evaporator case (lower) 1 37 Actuator (C) 1
5 Intake case (upper) 1 38 Actuator (F) 1
6 Clamp 1 39 Actuator (G) 1
7 Fan case (R) 1 40 Expansion valve 1
8 Fan case (L) 1 41 Valve 1
9 Insulator 1 42 Thermistor 1
10 Grommet (A) 1 43 Thermistor (C7) 1
11 Sensor grommet 1 44 Sensor 1
12 Filter 1 45 Harness 1
13 Filter & Cover 1 46 Resistor harness 1
13-1 Filter 1 47 Spring 1
13-2 Filter cover 1 48 Rod 1
14 Support 2 49 Link rod 1
15 Packing 1 50 Lever 1
16 DEF gasket 1 51 Rod (L53) 1
17 Vent gasket 2 52 Vent damper 1
18 DEF gasket 1 53 DEF damper 1
19 Insulator 1 54 Packing 1
20 Foot damper 2 55 Vent damper shaft 1
21 Bracket assembly 1 56 DEF damper shaft 1
22 Bracket assembly 1 57 Spring guide 1
23 Support (A) 1 58 Relay 5
24 Bracket 1 59 Amplifier (TKS-C201A0) 1
25 Resistor bracket assembly 1 60 Oil heater core 1
25-1 Resistor 1 61 Clamp 2
25-2 Resistor bracket 1 62 Rod clamp 5
25-3 Trim 1 63 Stay (E) 1
26 Pipe holder 1 64 Clamp (Z) 5
27 Cover 1 65 Rod holder 3
29 Pipe 1 66 Sensor holder 1
30 Hose 1 67 Clamp (CA) 3
31 Pipe 1 68 Clamp (CD) 2
32 Pipe (A) 1 69 Clamp 1
33 Band 2 70 Clamp 11

— 17 —
 Charge valve
(High pressure) High-pressure Sight glass
hose High-low pressure
switch

Low-pressure hose
Charge valve
(Low pressure)

Receiver drier
Relief valve

5181-008E-0 5181-009E-0

Compressor

Air conditioner unit Compressor

Water valve

Heater
V-belt
Engine

Evaporator High-pressure
Radiator hose
Expansion
valve L hose Condenser

Receiver drier

Low-pressure hose 5181-010E-0

Compressor Idle pulley

Belt inspection and adjustment

If the belt is not tightened properly, not only will the compressor
performance be reduced, but can cause abnormal noises or cause
belt or compressor damage.
Check the amount of slack in the belt.
Apply about 98.1N (10kgf) of force to the center section of the
pulleys and if the belt deflects about 8 ~ 12mm, it is normal.

Crank pulley
5181-011E-0

— 18 —
10. Refrigerant charging method (5181-011-0E)

10-1 Precautions for this procedure (5181-012-0E)

Be sure to have a specialist perform this procedure.

Refrigerant charging involves handling high pressure gas and is dangerous, so have a specialist who is thoroughly
familiar with the procedures perform the work.

CAUTION
• Be sure to wear protective glasses. (Refrigerant in your eyes could cause
blindness.)
• Liquid refrigerant is extremely cold, so be very careful handling it. (If it gets on
your skin it could cause frostbite.)

10-2 Precautions for storage and transit (5181-013-0E)

(1) Keep the service can below 40 . The can contains the high pressure HFC-134a gas as a saturated fluid, so
when the temperature rises, the pressure inside the can will rapidly rise and there is a danger the can would
burst.
(2) If the service can is to be stored, store it in a cool, dark location, and avoid direct sunlight.
(3) If the service can is placed near a flame, it will be affected by radiant heat which will raise the temperature
inside the can. The pressure inside the can will rise and there is a danger the can would burst, so never put
the can near a flame.
(4) If radiant heat from the sun enters the sealed operation cab, the temperature can rise very high. In addition,
those areas that receive direct sunlight can become dangerously hot, even in winter. Therefore, do not take
the service can into the operation cab.
(5) If the service can becomes scratched, dented, deformed etc., its strength is reduced so handle and store it
with extra care.
1) Do not drop or hit the can.
2) When transiting or unloading the can or case of cans, do not throw or drop them.
(6) Store the service can in a location out of the reach of children.

10-3 Precautions for refrigerant charging (5181-014-0E)

(1) If the service can is to be warmed in order to charge with refrigerant, be sure to open the service can valve
and gauge manifold low-pressure valve, then warm the can in warm water at not more than 40 (not hot to
the touch).
If it is placed in hot water or heated by direct flame the pressure inside the can will rise and there is a danger
the can would burst.
(2) If the engine is started and the refrigerant is charged, never open the high-pressure valve (Hi) on the gauge
manifold. If the high-pressure valve is opened, high pressure gas will flow in reverse and the service can or
charge hose can burst, so it is extremely dangerous.

— 19 —
10-4 Other precautions (5181-015-0E)
The law prohibits reusing the service cans, so never reuse them.
Be especially careful that no foreign matter gets into the air conditioner circuit.
If air, water or debris gets into the refrigeration cycle it can cause malfunctioning or a drop in performance, so
assemble the air conditioner parts accurately and promptly, always being careful of introducing foreign matter.
• Be careful not to overcharge with refrigerant.
• Tighten the hoses and lines to the regulation torque.

10-5 Charging procedure (5181-016-0E)

(1) The process of charging the air conditioner with refrigerant can be largely divided into two stages, “evacuation”
and “refrigerant charging”.
1) The evacuation process involves removing all moisture from within the air conditioner circuit. If even a
slight residual amount of moisture remains, when the air conditioner is operated the moisture will freeze
onto the expansion valve and may block the circuit or cause rust or cause various other problems.
Therefore, before charging the circuit with refrigerant, the circuit should be evacuated of all residual moisture
by boiling it into vapor.
2) The refrigerant charging process involves filling the evacuated circuit with refrigerant.
This process not only determines the cooling performance, but also affects the lifespan of the parts that
make up the circuit.
If the refrigerant is overcharged especially carelessly, then when the air conditioner is operated the pressure
inside the circuit will be abnormally high and the cooling capacity will be low.
Furthermore, if the refrigerant quantity is especially low, not only will the cooling capacity be low, but the
compressor will not receive proper lubrication and the sliding surfaces in the compressor might seize.
The refrigerant charging process involves handling high pressure gas, so performing the procedures incorrectly
is extremely dangerous. Follow the proper work procedures and observe the safety precautions when
charging with refrigerant.

[Refrigerant charging procedure chart]

Evacuation Refrigerant charging

Charge with refrigerant

Charge with refrigerant

Check for a gas leak
Check airtightness
Finish evacuation
Start evacuation

More than 30 Wait for 5 minutes Gauge indicates

minutes normal

Gauge indicates
problem

Check and fix Charge with refrigerant gas to

connections 0.098MPa (approx. 1kgf/cm2)

— 20 —
10-6 Refrigerant charging procedure (5181-017-0E)

(1) Evacuation Gauge manifold

1) Connecting the gauge manifold (see figure) Low-pressure

charge hose
Close the high-pressure valve (Hi) and low-pressure valve
(Lo) on the gauge manifold. High-pressure
charge hose
Connect the quick joints to the charge hoses.
High-pressure side (red): 27.5mm Quick joint (Hi)
Low-pressure side (blue): 23.5mm
Push the quick joints securely onto the charge valves
until they “click”.
Use the charge hose to connect the center valve on the Quick joint (Lo)

gauge manifold with the vacuum pump (see figure). Charge hose

5181-012E-0

Quick joint
• When connecting the quick joint, be careful not to bend Sleeve
the tubing as you push. Charge valve
• When connecting the hose, if any refrigerant is left in the
charge hose it can be difficult to connect it, so remove any
residual pressure from the hose before beginning.

Push until there is

a click sound. 5181-013E-0

High-pressure gauge
Low-pressure gauge
Gauge manifold

High-pressure valve (close)

Low-pressure valve (close)
Red
Blue
Yellow
High-pressure side DIS

Vacuum pump (stop)

Low-pressure
side SUC

Compressor
5181-014E-0

— 21 —
 2) Evacuation
Open the high-pressure valve (Hi) and low-pressure valve
(Lo) on the gauge manifold. Low-pressure valve (open) (close)
High-pressure valve (open) (close)
Turn on the vacuum pump switch and evacuate the circuit 30 minutes
or more
for over 30 minutes.
After evacuating the circuit for the specified time (reach
a vacuum of: –750mg Hg or lower) close the high-pressure Low-pressure valve High-pressure
(open) valve (open)
valve and low-pressure valve on the gauge manifold.
Turn the vacuum pump switch off. Gauge manifold

High-pressure
side DIS
3) Airtightness check
Keep the high-pressure valve and low-pressure valve on
the gauge manifold closed for 5 minutes or more and
Low-pressure
confirm that the gauge needle positions do not return to 0 side SUC
(zero). 5181-015E-0

• If the gauge needle seems to be moving back toward 0

(zero), there must be a leak somewhere in the lines. Tighten
the connection points, evacuate the circuit again and make
sure there are no leaks.

(2) Refrigerant charging Air purge

1) Charging from the high-pressure side Close

Open the service
After evacuating the circuit, move the charge hose that Blue can valve.
Red
is in the center of the gauge manifold, from the vacuum Yellow
pump to the service can. Screwdriver
etc.
Air purge
Open the service can valve (provided the high and low-
pressure valves on the gauge manifold are closed).
Next, use a screwdriver etc. to push the side service port 5181-016E-0

valve on the low-pressure side of the gauge manifold and

purge the air from inside the charge hoses using the pressure
High-pressure valve
from the refrigerant (see figure). You are finished when (open) (close)
Charge with 1 ~
you hear the hissing sound of air leaving the hose. 1.5 service cans.
Low-pressure valve
Open the high-pressure valve on the gauge manifold and (close) Red
charge the circuit with refrigerant. (It will enter as gas Blue

refrigerant until the gauge pressure reaches 0.098MPa DIS Yellow

(approx. 1kgf/cm ).)

2
Service can valve
After charging the circuit, close the high-pressure valve (open) (close)
Charging
on the gauge manifold and the service can valve (see SUC
figure).
CAUTION
Never operate the compressor when the high-pressure
5181-017E-0
valve is open on the gauge manifold.
It would cause the refrigerant to flow in reverse and burst
the service can or hose, so it is extremely dangerous.

— 22 —
2) Gas leak check
Check the system for gas leaks using a gas leak tester. If
there is a leak, fix it by tightening the connection points.

CAUTION
Be sure to use an HFC-134a type leak tester. (The
R12 type is not sensitive enough and will not make a
proper determination.)

3) Charging from the low-pressure side

Low-pressure valve
Make sure the high-pressure valve and low-pressure
Open Close High-pressure valve
valve on the gauge manifold and the service can valve When bubbles (close)
disappear from (Close it securely.)
are all closed. Red
the sight glass Blue
Start the engine and set the engine speed to 1500
Yellow
100min–1 (1500 100rpm). Open the operation cab door
DIS
and windows fully.
Turn on the air conditioner switch, set the air volume SUC

switch to maximum, and the temperature setting switch

to COOL-MAX. Set the air outlet mode to FACE and Compressor in Service can
the air source mode to RECIRC. operation (Do not invert it.)

Open the low-pressure valve on the gauge manifold and

5181-018E-0
the service can valve. Charge the circuit until the bubbles
disappear from the receiver drier sight glass. (Refrigerant
charging quantity 1050g)
When charging with refrigerant is complete, close the
low-pressure valve on the gauge manifold and the service
Sight glass
can valve, and turn off the engine.

CAUTION
• Never open the high-pressure valve on the gauge
manifold. Gas will flow in reverse, bursting the service
can or hose, so it is dangerous.
• Never invert the service can. (If liquid refrigerant gets
into the compressor, there is a chance it will damage
a valve and lead to a malfunction.) Receiver drier

• Be sure to fill the circuit with the appropriate amount

of refrigerant. Overcharging the circuit will cause the
707E-430E-0
high-pressure side pressure to increase rapidly (the
low-pressure side will also increase) and have a
negative effect on the air conditioner system, so make
sure it is not overcharged.

— 23 —
(3) Guidelines for determining how much refrigerant to charge
Refrigerant quantity determination as seen from the receiver drier

After turning ON 1 minute later After turning the A/C switch ON,
a few bubbles are visible,
becoming transparent and then
Properly charged slightly milky (or becoming
transparent and slightly milky
alternatively).

After turning the A/C switch ON,

no bubbles are visible at all.
Overcharged

After turning the A/C switch ON,

bubbles are continuously visible.
Undercharged

5181-019E-0

1) If the air conditioner is operated when the refrigerant amount is extremely low, it will be bad for the compressor.
2) If the circuit is charged with too much refrigerant (overcharged), the cooling capacity will drop and the
pressure within the circuit will rise abnormally high, so it is dangerous. Use the proper amount of refrigerant.

(4) Removing the gauge manifold

After inspecting the refrigerant, remove the charge hoses from the compressor using the following procedure.
1) Turn the main power switch OFF and turn off the engine.
2) After the air conditioner is OFF, confirm that the pressure inside the circuit has balanced. Slide the quick
joint sleeve on the low-pressure charge hose (blue) up and remove the hose from the charge valve. Then
use the same procedure to remove the high-pressure charge hose.

Sleeve

While holding section A of the quick joint fixed, slide section B

(the sleeve) up.

Push until there Removal is complete.

is a click sound. CAUTION
After removal, be sure to put a cap on the charge valve.

5181-020E-0

— 24 —
11. Troubleshooting (5181-018-0E)

(1) The air outlet mode does not switch

The mode LED on the control panel flashes and an E

is shown on the temperature setting display section.

NO YES

Does the rod come off? Is the motor actuator locked?

NO YES NO YES

Repair mode damper Repair Inspect harness Inspect actuator

(2) The air source mode (FRESH/RECIRC) does not switch

The mode LED on the control panel flashes and an E

is shown on the temperature setting display section.

NO YES

Does the rod come off? Is the motor actuator locked?

NO YES NO YES

Repair mode damper Repair Inspect harness Inspect actuator

— 25 —
(3) The blower motor does not shift speeds

It turns in the III position in manual control.

NO YES

Check using the section “The It only turns in the I position. It only turns in the II position.
blower motor does not turn”.

Is there conductivity between Is there conductivity between

blue and spring green terminals blue and yellow terminals on the
on the resistor 4P coupler? resistor 4P coupler?

NO YES NO YES

Inspect resistor Inspect Inspect resistor Inspect

(1) Harness (1) Harness
(2) Relay (2) Relay

— 26 —
(4) The blower motor does not turn

There is battery voltage between red (+) and blue (–) blower terminals,
when the hydraulic excavator starter switch is “ON”, the main switch
is “ON” and the air volume switch is at III, both on the control panel.

NO YES

Is there battery voltage between the body and the The blower motor is defective.
blower motor (+) side power source red terminal?

NO YES

The blower motor (+) side wiring is defective. The blower motor (–) side wiring is defective.
Inspect Inspect
(1) Fuse (1) Wire harness
(2) Wire harness (2) Control amplifier
(3) Machine side ground wiring

— 27 —
(5) The magnetic clutch does not engage

The compressor control indicator is lit.

NO YES

Is an E shown on the temperature Is electric power reaching the clutch?

setting display section?
NO YES
NO YES
Is there terminal voltage along The clutch is
Replace amplifier The evaporation the pressure switch harness? defective.
sensor is defective.
NO YES

It there battery voltage at the The pressure switch is defective or there

red clutch relay terminal? is too little or too much refrigerant.

NO YES

Inspect fuse and harness Does the clutch go ON when the

clutch relay red terminal and clutch
green terminal are directly connected?

NO YES

Inspect harness If the clutch relay green/black terminal

is connected to ground, does it go ON?

NO YES

Replace relay Inspect harness or

replace amplifier

— 28 —
(6) The temperature does not rise

An E is shown on the panel temperature setting display section.

NO YES

Does the outlet temperature rise when the tem- Is the compressor control
perature setting is set to HOT-MAX (32.0 )? indicator lit?

NO YES NO YES

Is the flow regulator valve Inspect control amplifier When the compressor control
in the fully open position switch is pressed, does the
when set to HOT-MAX? control indicator turn off?
NO YES
NO YES
Inspect flow regulator valve Is there a leak from the
actuator and valve rod heater hose section? Inspect control Inspect evapora-
amplifier tion sensor and
NO YES air outlet sensor

Inspect water temperature Inspect and repair

sensor, air outlet sensor and leak location
internal air temperature sensor

Is the temperature
regulator valve motor
actuator locked?

NO YES

Inspect or replace the motor Repair cause of lock or

actuator connector connection replace actuator
and the wiring between the
motor actuator and amplifier.

— 29 —
(7) The temperature does not go down

An E is shown on the panel temperature setting display section.

NO YES

Does the outlet temperature go down when the

temperature setting is set to COOL-MAX (18.0 )?

NO YES

Is the flow regulator valve Inspect control amplifier

in the fully closed position
when set to COOL-MAX?

NO YES

Inspect flow regulator Inspect compressor clutch circuit

valve and valve rod
Is the temperature When the compressor control
regulator valve motor switch is pressed, does the
actuator locked? control indicator light?

NO YES

Inspect or replace the motor Repair cause of lock or

actuator connector connection replace actuator
and the wiring between the
motor actuator and amplifier.

NO YES

Inspect the evaporation sensor for Inspect the outside air tempera-
a break in the circuit or the con- ture sensor and air outlet sensor
nector for a bad connection. for a break in the circuit or the
connector for a bad connection.

— 30 —
12. Electrical circuit diagram (5181-019-0E)

TUA-R104 (A/C unit)

0.5 0.5 Backup memory power source

0.5 0.5 Night illumination power source 0.5

X1 N.O 2.0 15A 2.0 Main power source

0.85 2.0 0.5 0.5 0.85

ACC
IGN.SW
0.5 IGN
Blower
STA
M motor
(183W) 0.85 0.85 0.85 0.85 0.85
1A 1A

2.0 0.5 0.5

2.0
RY2 RY3 RY4 RY5 RY6
0.85
Temperature
fuse 0.5 0.5 0.5 0.5 0.5
Resistor
N.O
0.5
Control amplifier
Battery
X6 Control panel (TKS-C201A0)
24V Solar radiation sensor
(TKS-P201A0) 0.5 0.5
0.85
RY1 Internal air
0.85 LED (illumination) temperature sensor
0.5 0.5
Outside air
temperature sensor
0.5 0.5
5A Water temperature
sensor
0.85 Pressure SW 0.5 0.5
Low pressure 0.85 Evaporation sensor
0.196MPa (2kgf/cm2) 0.5 0.5
(Deff 0.02)
High pressure Air outlet sensor
3.14MPa (32kgf/cm2) 0.5 0.5
0.85
(Deff 0.59) 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5
(Applied current
value 2.5A) 0.85 0.5 0.5 0.5 0.5
1.25
N.O N.O N.O N.O

MgC
(34W) X2 X3 X4 X5 M M M M

Motor ACT4 Motor ACT3 Motor ACT2 Motor ACT1

(Mode) (Water valve) (DEF) (Internal/outside air switching)

1.25 2.0 0.85 0.85 0.85 0.5 0.5

5181-02E-2

— 31 —
MEMO

— 32 —