Fujitsu ASU18RLF Operating instructions

SPLIT TYPE
ROOM AIR CONDITIONER
WALL MOUNTEDtype
Models Indoor unit Outdoor unit
INVERTER
SERVICE
INSTRUCTION
R410A
ASU18RLF
ASU24RLF
AOU18RLXFW
AOU24RLXFW

CONTENTS
1. DESCRIPTION OF EACH CONTROL OPERATION
1. COOLING OPERATION................................................................................................
3. DRY OPERATION.........................................................................................................
2. HEATING OPERATION.................................................................................................
5. INDOOR FAN CONTROL..............................................................................................
4. AUTO CHANGEOVER OPERATION............................................................................
7. LOUVER CONTROL.....................................................................................................
6. OUTDOOR FAN CONTROL..........................................................................................
9. TIMER OPERATION CONTROL...................................................................................
8. COMPRESSOR CONTROL..........................................................................................
11. TEST OPERATION CONTROL...................................................................................
10. ELECTRONIC EXPANSION VALVE CONTROL........................................................
13. FOUR-WAY VALVE EXTENSION SELECT................................................................
12. PREVENT TO RESTART FOR 3 MINUTES ( 3 MINUTES ST ).................................
15. MANUAL AUTO OPERATION ( Indoor unit body operation ).....................................
14. AUTO RESTART.........................................................................................................
16. FORCED COOLING OPERATION..............................................................................
18. MINIMUM HEAT OPERATION....................................................................................
17. COMPRESSOR PREHEATING..................................................................................
19. ECONOMY OPERATION............................................................................................
21. OFF DEFROST OPERATION CONTROL...................................................................
20. DEFROST OPERATION CONTROL...........................................................................
01-01
01-02
01-02
01-03
01-04
01-06
01-07
01-08
01-09
01-11
01-11
01-11
01-11
01-12
01-12
01-12
01-12
01-12
01-13
01-15
22. VARIOUS PROTECTIONS.......................................................................................... 01-16
01-11
2. TROUBLE SHOOTING
2-1 ERROR DISPLAY.......................................................................................................
2-1-1INDOOR UNIT AND WIRED REMOTE CONTROLLER DISPLAY ...............................
3. APPENDING DATA
2-1-2 WIRED REMOTE CONTROLLER DISPLAY.............................................................
2-2 TROUBLE SHOOTING WITH ERROR CODE............................................................
2-3 TROUBLE SHOOTING WITH NO ERROR CODE.....................................................
02-01
02-01
02-02
3-1 FUNCTION SETTING.................................................................................................
3-1-1 INDOOR UNIT........................................................................................................
3-1-2 PROCEDURSE TO CHANGE THE FUNCTION SETTING FOR WIRELESS RC..........
03-01
03-01
03-03
3-3 THERMISTOR RESISTANCE VALUES...................................................................... 03-09
02-03
02-23
2-4 SERVICE PARTS INFORMATION.............................................................................. 02-28
3-2 OUTDOOR UNIT PRESSURE VALUE AND
TOTAL ELECTRIC CURRENT CURVE............... 03-05

1 . DESCRIPTION OF EACH
CONTROL OPERATION
R410A
WALL MOUNTED type
INVERTER

( Fig.1 : Limit of Maximum Frequency based on Outdoor Temperature )
1. COOLING OPERATION
1-1 COOLING CAPACITY CONTROL
A sensor (room temperature thermistor) built in the indoor unit body will usually perceive
difference or variation between a set temperature and present room temperature, and
controls the operation frequency of the compressor.
* If the room temperature is 4°F(2°C) higher than a set temperature, the compressor operation
frequency will attain to maximum performance.
minimum
frequency
maximum
frequency
ASU18RLF 12rps 55rps
ASU24RLF 16rps 72rps
Outside air Outside air
temperature temperature
96.8°F
(36°C)
A zone
93.2°F
(34°C) 89.6°F
(32°C)
B zone
86°F
(30°C) 69.8°F
(21°C)
C zone
66.2°F
(19°C)
D zone
Hi Me Lo Quiet
A zone 55rps 36rps 29rps 25rps
B zone 55rps 36rps 29rps 25rps
C zone 47rps 36rps 29rps 25rps
18RLF
D zone 37rps 33rps 26rps 20rps
E zone 37rps 33rps 26rps 20rps
F zone 37rps 33rps 26rps 20rps
72rps 49rps 41rps 29rps
72rps 49rps 41rps 29rps
55rps 41rps 36rps 29rps
43rps 36rps 31rps 20rps
43rps 36rps 31rps 20rps
41rps 36rps 31rps 20rps
A zone
B zone
C zone
24RLF
D zone
E zone
F zone
( Table1 : Compressor Frequency Range )
01-01
E zone
F zone
50°F
(10°C)
32°F
(0°C)
53.6°F
(12°C)
35.6°F
(2°C)
* When the room temperature is between +4°F(+2°C) to -5°F(-2.5°C) of the setting temperature,
the compressor frequency is controlled within the range shown in Table1.
However, the maximum frequency is limited in the range shown in Figure1 based on the
fan speed mode and the outdoor temperature.
* If the room temperature is 5°F(2.5°C) lower than a set temperature, the compressor will be
stopped.

2. HEATING OPERATION
2-1 HEATING CAPACITY CONTROL
A sensor (room temperature thermistor) built in the indoor unit body will usually perceive
difference or variation between a set temperature and present room temperature, and
controls the operation frequency of the compressor.
* If the room temperature is lower by 6°F(3°C) than a set temperature, the compressor operation
frequency will attain to maximum performance.
* If the room temperature is higher 5°F(2.5°C) than a set temperatire, the compressor will be
stopped.
* When the room temperature is between +5°F(+2.5°C) to -6°F(-3°C) of the setting temperature,
the compressor frequency is controlled within the range shown in Table2.
( Table2 : Compressor Frequency Range )
01-02
minimum
frequency
maximum
frequency
ASU18RLF 14rps 67rps
ASU24RLF 16rps 90rps
3. DRY OPERATION
3-1 INDOOR UNIT CONTROL
The compressor rotation frequency shall change according to the temperature, set temperature,
and room temperature variation which the room temperature sensor of the indoor unit body has
detected as shown in the Table3.
However, after the compressor is driven, the indoor unit shall run at operation frequency of
30rps (18RLF), 30rps (24RLF), for a minute.
Ts+1°F
(Ts+0.5°C) Ts-1°F
(Ts-0.5°C)
Ts-3°F
(Ts-1.5°C)
Ts+3°F
(Ts+1.5°C)
( Table3 : Compressor frequency )
( Fig.2 : Compressor Control based on Room Temperature )
Operating
frequency
25rps
15rps
0rps
18RLF X zone
J zone
Y zone
Operating
frequency
J zone
Y zone
X zone 29rps
16rps
0rps
24RLF
Room Room
temperature temperature
X zone
J zone
Y zone

4. AUTO CHANGEOVER OPERATION
01-03
Operation flow chart
START
Room temp.
Room temp.
>Ts+4°F(2°C)?
COOLING OPERATION
HEATING OPERATION
YES
YES
NO
NO
NO
NO
YES
YES
TS: Setting temperature
<Ts- 4°F(2°C)?
Thermostat remains
in OFF state for 6 minutes or
longer?
System stops
or operation command other than
auto changeover operation?
NO
NO
Thermostat remains
in OFF state for 6 minutes or
longer?
System stops
or operation command other than
auto changeover operation?
YES
YES
When the air conditioner is set to the AUTO mode by remote control, operation starts in the optimum
mode from among the HEATING, COOLING, DRY and MONITORING modes. During operation, the
optimum mode is automatically switched in accordance with temperature changes. The temperature
can be set between 64°F(18°C) and 88°F(30°C) in 2°F(1°C) steps.

5. INDOOR FAN CONTROL
The airflow can be switched in 5 steps such as AUTO, QUIET, LOW, MED, HIGH,
while the indoor fan only runs.
When Fan mode is set at (Auto), it operates on (MED) Fan Speed.
01-04
1. Fan speed
2. FAN OPERATION
( Table4 : Indoor Fan Speed )
Operation mode Air flow mode Speed (rpm)
1260
1120
1020
900
Cooling/ Fan
Hi
Hi
790
680
270
1260
Me+
Me
Me
Heating
Lo
Lo
1020
900
Quiet
Quiet
770
Dry
S-Lo
X zone : 770
J zone : 720
1530
1320
1220
1020
900
720
270
1480
1220
1020
900
X zone : 900
J zone : 850
Cool air prevention
3. COOLING OPERATION
Switch the airflow [AUTO], and the indoor fan motor will run according to a room temperature,
as shown in Figure3.
On the other hand, if switched in [HIGH] [QUIET], the indoor motor will run at a constant airflow of [COOL]
operation modes QUIET, LOW, MED, HIGH,as shown in Table4.
( Fig.3 : Airflow change - over ( Cooling : AUTO ) )
When the room
temperature rises
When the room
temperature drops
TR : Room temperature
Ts : Setting temperature
TR-Ts > 4°F
(2°C)
2°F > TR-Ts
(1°C)
4°F > TR-Ts > 2°F
(2°C) (1°C)
=
TR-Ts > 5°F
(2.5°C)
=
3°F > TR-Ts
(1.5°C)
5°F > TR-Ts > 3°F
(2.5°C) (1.5°C)
=
HIGH mode
MED mode
LOW mode
ASU18RLF ASU24RLF
4. DRY OPERATION
Refer to the Table4.
During the dry modeoperation,the fan speedsetting can notbe changed.

The maximum value of the indoor fan speed is set as shown in Figure5, based on the detected
temperature by the indoor heat exchanger sensor on heating mode.
(Fig.5 : Cool Air Prevention Control)
01-05
5. HEATING OPERATION
Switch the airflow [AUTO], and the indoor fan motor will run according to a room temperature,
as shown in Figure4.
On the other hand, if switched in [HIGH] [QUIET], the indoor motor will run at a constant airflow
of [HEAT] operation modes QUIET, LOW, MED, HIGH, as shown in Table4.
6. COOL AIR PREVENTION CONTROL (Heating mode)
( Fig.4 : Airflow change - over ( Heating : AUTO ) )
TR-Ts > -3°F
(-1.5°C)
=
-5°F > TR-Ts
(-2.5°C)
-3°F > TR-Ts > -5°F
(-1.5°C) (-2.5°C)
=
TR-Ts > -2°F
(-1°C)
=
-4°F > TR-Ts
(-2°C)
-2°F > TR-Ts > -4°F
(-1°C) (-2°C)
=
When the room
temperature rises When the room
temperature drops
TR : Room temperature
Ts : Setting temperature
LOW mode
MED mode
MED+ mode
107.6°F (42°C)
86°F (30°C)
93.2°F (34°C)
Indoor heat exchanger
temperature Indoor heat exchanger
temperature
Hi
Me+
Lo
Cool air
prevention
102.2°F (39°C)
98.6°F (37°C)
98.6°F (37°C)
89.6°F (32°C)
82.4°F (28°C)
S-Lo

6. OUTDOOR FAN CONTROL
( Table6 : Outdoor fan speed )
*The outdoor fan speed mentioned above depends on the compressor frequency.
(When the compressor frequency increases, the outdoor fan speed also changes to the higher
speed. When the compressor frequency decreases, the outdoor fan speed also changes to the
lower speed.)
*After the defrost control is operated on the heating mode, the fan speed keeps at the higher speed
as table8 without relating to the compressor frequency.
01-06
( Table7 : Outdoor fan speed after the defrost )
1. Outdoor Fan Motor
2. Fan Speed
AC Motor DC Motor
ASU18 / 24RLF
Following table shows the type of the outdoor fan motor. The control method is different
between AC motor and DC motor.
( Table5 : Type of Motor )
ASU18RLF 800rpm
Cooling Heating
ASU18RLF
ASU24RLF
D
F
Zone
800/ 620/ 500/ 400
800/ 620/ 550/ 450
900/ 850/ 800/ 620/ 550/ 450
Refer to Fig.6
(rpm)
500/ 320/ 250
G
H
300/ 230/ 200
220/ 200
D
F
850/ 800/ 620/ 500/ 400
500/ 320/ 250
G
H
300/ 230/ 200
220/ 200
Dry
550/ 450
550/ 450
ASU24RLF 900rpm
( Fig.6 : Outside air temperature zone selection )
53.6°F (12°C)
32°F ( 0°C)
Outside air
temperature
Outside air
temperature
F zone
D zone
G zone
H zone
35.6°F (2°C)
17.6°F (-8°C)
50°F (10°C)
14°F ( -10°C)

1-5. LOUVER CONTROL
Each time the button is pressed, the air direction range will change as follow:
(Function Range)
(Table9 : Operation Range)
01-07
Use the air direction adjustments within the ranges shown above.
The vertical airflow direction is set automatically as shown, in accordance with the type of operation selected.
Cooling / Dry mode : Horizontal flow
Heating mode : Downward flow
When the temperature of the air being blown out is low at the start of heating operation or during
defrosting, the airflow direction temporarily becomes to prevent cold air being blown onto the body.
During use of the Cooling and Dry modes, do not set the Air Flow Direction Louver in the Heating
range ( ) for long period of time, since water vapor many condense near the outlet louvers and
drop of water may drip from the air conditioner. During the Cooling and Dry modes, if the Air Flow
Direction Louvers are left in the heating range for around 30 minutes, they will automatically
return to position .
(Fig.7 : Virtical Air Direction Range)
Cooling / Dry / Fan mode( ) :
Heating / Fan mode( ) :
3. SWING OPERATION
When the swing signal is received from the remote controller, the vertical louver starts to swing.
(Swinging Range)
1 3 14
46
Vertical Airflow Swing Operation
Horizontal Airflow Swing Operation
When the swing signal is received from the remote controller, the horizontal louver starts to swing.
Cooling / Heating / Dry / Fan mode :
(Swinging Range)
5
1
Vertical and Horizontal Airflow Swing Operation
When the indoor fan is S-Lo or Stop mode, the swing operation is interrupted
and it stops at either upper end or bottom end.
When the indoor fan is S-Lo or Stop mode, the swing operation is interrupted
and it stops at either upper end or bottom end.
When the horizontal swing signal is input from remote control, the combination of the vertical
and horizontal swing operation is performed.
12345
2. HORIZONTAL LOUVER CONTROL
Horizontal Louver
Each time the button is pressed, the air directionrange will change as follows.
(Function Range)
Cooling / Heating / Dry / Fan mode
(Fig.8 : Horizontal Air Direction Range)
Power Diffuser doesn't swing in any swing operation.
1. VERTICAL LOUVER CONTROL
Power DiffuserVertical Louver
<Wall Mounted Type>
ASU7/9/12RLF changes by manual.
3 6
Cooling / Dry mode
Heating mode
Fan mode

8. COMPRESSOR CONTROL
1. OPEARTION FREQUENCY RANGE
The operation frequency of the compressor is different based on the operation mode as
shown in the table8.
Cooling Heating
Min Max Min Max Min Max
Dry
ASU18RLF
ASU24RLF
12rps 55rps 14rps 67rps 15rps 25rps
16rps 72rps 16rps 90rps 16rps 29rps
(Table8 : Compressor Operation Frequency Range)
2. OPEARTION FREQUENCY CONTROL AT START UP
The compressor frequency soon after the start-up is controlled as shown in the Figure9.
(Fig.9 : Compressor Control at Start-up)
01-08
30rps
60sec
47rps
60rps
120sec 180sec

9. TIMER OPEARTION CONTROL
1. OPEARTION FREQUENCY RANGE
The table9 shows the available timer setting based on the product model.
ON TIMER / OFF TIMER PROGRAM TIMER SLEEP TIMER
ASU18/ 24RLF
OFF timer : When the clock reaches the set time, the air conditioner will be turned off.
Operation mode
Stop mode
Set time of timer
ON timer : When the clock reaches the set time, the air conditioner will be turned on.
Operation mode
Stop mode
Set time of timer
The program timer allows the OFF timer and ON timer to be used in combination one time.
Operation mode
Operation will start from the timer setting (either OFF timer or ON timer) whichever is closest
to the clock's current timer setting.
The order of operations is indicated by the arrow in the remote control unit's display.
SLEEP timer operation cannot be combined with ON timer operation.
(Table9 : Timer Setting)
2. PROGRAM TIMER
Stop mode Stop mode Stop mode
Operation mode Operation mode
Set time Set time Set time Set time
01-09

3. SLEEP TIMER
If the sleep is set, the room temperature is monitored and the operation is stopped automatically.
If the operation mode or the set temperature is change after the sleep timer is set, the operation is
continued according to the changed setting of the sleep timer from that time ON.
Set temperature rises
( Ts : Set temperature )
Stop of operation
Set temperature lowers
( Ts : Set temperature )
Ts
Stop of operation
In the cooling operation mode
When the sleep timer is set, the setting temperature is increased 2°F(1°C).
It increases the setting temperature another 2°F(1°C) after 1 hour.
After that, the setting temperature is not changed and the operation is stopped at the time
of timer setting.
Ts
+2°F (1°C)
+4°F (2°C)
Set 60min
In the heating operation mode
When the sleep timer is set, the setting temperature is decreased 2°F(1°C).
It decreases the setting temperature another 2°F(1°C) every 30 minutes.
Upon lowering 8°F(4°C) the setting temperature is not changed and the operation stops at
the time of timer setting.
-8°F (-4°C)
-6°F (-3°C)
-4°F (-2°C)
-2°F (-1°C)
Set 30min 30min 30min
01-10

10. ELECTRONIC EXPANSION VALVE CONTROL
The most proper opening of the electronic expansion valve is calculated and controlled under the
present operating condition based on the Table12.
The compressor frequency, the temperatures detected by the discharge temperature sensor, the
indoor heat exchanger sensor, the outdoor heat exchanger sensor,
and the outdoor temperature sensor.
The expansion valve is set at 480 pulses after 120 seconds of stopping compressor.
At the time of supplying the power to the outdoor unit, the initialization of the electronic
expansion valve is operated (528 pulses are input to the closing direction).
11. TEST OPERATION CONTROL
Under the condition where the air conditioner runs, press the test run button of the remote
control, and the test operation control mode will appear. During test running, the operation lamp
and timer lamp of the air conditioner body twinkle simultaneously. Set the test operation mode,
and the compressor will continue to run regardless of whether the room temperature sensor detects.
The test operation mode is released if 60 minutes have passed after setting up the test operation.
The compressor won't enter operation status for 3 minutes after the compressor is stopped,
even if any operation is given.
At the time when the air conditioner is switched from the cooling mode to heating mode, the
compressor is stopped, and the four-way valve is switched in 3 minutes later after the compressor
stopped.
When the power was interrupted by a power failure, etc. during operation, the operation contents
at that time are memorized and when power is recovered, operation is automatically started with
the memorized operation contents.
When the power is interrupted and recovered during timer operation, since the timer operation time
is shifted by the time the power was interrupted, an alarm is given by blinking (7 sec ON/2 sec OFF)
the indoor unit body timer lamp.
[Operation contents memorized when the power is interrupted]
Operation mode
Set temperature
Set air flow
Timer mode and timer time
Set air flow Direction
Swing
ECONOMY operation
MINIMUM HEAT operation
12. PREVENT TO RESTART FOR 3 MINUTES ( 3 MINUTES ST )
13. FOUR-WAY VALVE EXTENSION SELECT
14. AUTO RESTART
01-11
Cooling / Dry mode
Heating mode
Cooling / Dry mode
Heating mode
ASU18RLF
ASU24RLF
Operation mode Pulse range
between 52 to 480 pulses.
between 40 to 480 pulses.
between 53 to 480 pulses.
between 40 to 480 pulses.
Table10 : The pulse range of the electronic expansion valve control

15. MANUAL AUTO OPERATION (Indoor unit body operation)
If MANUAL AUTO Button is set, the operation is controlled as shown in Table11.
If the remote control is lost or battery power dissipated, this function will work without the remote control.
OPERATION MODE Auto changeover
FAN CONT. MODE Auto
TIMER MODE Continuous
SETTING TEMP. 75.2°F (24°C)
SETTING LOUVER Standard
SWING
ECONOMY
OFF
OFF
When the outdoor temperature is lower than 68°F(20°C) and the all operation mode has been
stopped for 30 minutes, power is applied to the compressor and the compressor is heated.
(By heating the compressor, warm air is quickly discharged when operation is started.)
When operation was started and when the outdoor temperature rises to 77°F(25°C) or greater,
preheating is ended.
(Table11)
(No timer setting available)
17. COMPRESSOR PREHEATING
01-12
Forced cooling operation
Cooling
16. FORCED COOLING OPERATION
Forced cooling operation is started when pressing MANUAL AUTO button for 10 seconds or more.
During the forced cooling operation, it operates regardless of room temperature sensor.
Operation LED and timer LED blink during the forced cooling operation. They blink for 1 second ON
and 1 second OFF on both operation LED and timer LED (same as test operation).
Forced cooling operation is released after 60 minutes of starting operation.
The FORCED COOLING OPERATION will start as shown in Table11.
Hi
Horizontal
OFF
Room Temp is not controlled
Manual auto operation
-
-
18. MINIMUM HEAT OPERATION
The MINIMUM HEAT operation functions by pressing MIN.HEAT button on the remote controller.
The MINIMUM HEAT operation is almost the same operation as below settings.
Mode Heating
Setting temperature 50°F (10°C)
Fan mode AUTO
( Table12 )
19. ECONOMY OPERATION
The ECONOMY operation functions by pressing ECONOMY button on the remote controller.
The ECONOMY operation is almost the same operation as below settings.
Mode Cooling/ Dry Heating
Target temperature Setting temp.+2°F Setting temp.-2°F
(+1°C) (-1°C)
( Table13 )

20. DEFROST OPERATION CONTROL
01-13
1. CONDITION OF STARTING THE DEFROST OPERATION
Integratingdefrost
(Constant monitoring)
If the compressor continuous operation time is less than 10 minutes,
the OFF number of the compressor is counted.
If any defrost operated, the compressor OFF count is cleared.
2. CONDITION OF THE DEFROST OPERATION COMPLETION
Defrost operation is released when the conditions becomes as shown in Table 17.
( Table 17 : Condition of defrost release )
Release Condition
Outdoor heat exchanger temperature is higher than 55.4°F(13°C)
or
Compressor operation time has passed 15 minutes.
The defrost operation starts as shown in the following Table 14, 15, and 16.
From 2nd and later
defrost after
starting operation
Less than 35 minutes More than 35 minutes
Does not operate
Compressor integrating operation time
( Table 14 : Condition of 1st defrost operation)
1st defrost
after
starting operation
Compressor integrating operation time
Less than 22 minutes More than 22 minutes More than 62 minutes
Does not operate Outdoor heat exchanger temperature
Below 15.8°F (-9°C )
Outdoor heat exchanger temperature
Below 21.2°F (-6°C)
Outdoor heat exchanger temperature
Below 23°F (-5°C )
More than 210 minutes
( For long continuous operation )
Less than 10 minutes
( For intermittent operation )
Compressor integrating operation time
Outdoor heat exchanger temperature
Below 26.6°F (-3°C)
OFF count of the compressor
40 times
( Table 16 : Condition of Integrating defrost operation)
( Table 15 : Condition of 2nd defrost operation)

01-14
3. Defrost Flow Chart
The defrosting shall proceed by the integrating operation time, outdoor temperature
and outdoor heat exchanger temperature as follows.
(Not defrosted for 10 minutes)
Heating operation start : Compressor ON
Outdoor heat exchanger temperature: Over 55° F(13°C)
or
Compressor ON time: Maximum 15 minutes
Defrost end
Compressor
integrating
operation:
Over 22 minutes
Compressor
integrating
operation:
Over 62 minutes
Outdoor
heat exchanger
temperature:
Below 15.8°F(- 9°C)
Outdoor
heat exchanger
temperature:
Below 23°F(- 5°C)
Compressor
integrating
operation:
Over 35 minutes
2nd and later defrost
Compressor : OFF
Outdoor fan motor : OFF
30 sec later 4-way valve : OFF
35 sec later compressor : ON
Compressor
integrating
operation:
Over 210 minutes
Integrating defrost
(Constant monitoring)
Defrost Indicator:
[Operation lamp]
7 sec ON / 2 sec OFF
Defrost start
Outdoor
heat exchanger
temperature:
Below 21.2°F(- 6°C)
Outdoor
heat exchanger
temperature:
Below 26.6°F(- 3°C)
Compressor
OFF count :
40 times
1st defrost

21. OFF DEFROST OPEARTION CONTROL
01-15
1. OFF DEFROST OPERATION CONDITION
When operation stops in the [Heating operation] mode, if frost is adhered to the outdoor unit heat
exchanger, the defrost operation will proceed automatically. In this time, if indoor unit operation
lamp flashes slowly (7 sec ON / 2 sec OFF), the outdoor unit will allow the heat exchanger to defrost,
and then stop.
In heating operation, the outdoor heat exchanger temperature is less than 24.8°F(-4°C), and
compressor operation integrating time lasts for more than 30 minutes.
OFF Defrost Flow Chart
Heating operation stop
Outdoor heat exchanger temperature :
Below 24.8°F(-4°C)
and
Compressor integrating operation :
Over 30 minutes
Defrost start
Defrost Indicater:
[Operation lamp]
7 sec ON / 2 sec OFF
Outdoor heat exchanger temperature : Over 55.4°F(13°C)
or
Compressor ON time : Maximum 15 minutes
Defrost end
2. OFF DEFROST RELEASE CONDITION
Release Condition
Outdoor heat exchanger temperature is higher than 55.4°F(13°C)
or
Compressor operation time has passed 15 minutes.
( Table 18 : OFF Defrost Release Condition )
OFF defrost operation is released when the conditions becomes as shown in Table 18.

22. VARIOUS PROTECTIONS
1. DISCHARGE GAS TEMPERATURE OVERRISE PREVENSION CONTROL
The discharge gas thermosensor (discharge thermistor : Outdoor side) will detect discharge gas
temperature.
ASU18/ 24RLF 219.2°F
(104°C)
213.8°F
(101°C)
230°F
(110°C)
When the discharge temperature becomes higher than Temperature ,the compressor frequency
is decreased 10rps, and it continues to decrease the frequency for 10rps every 120 seconds until
the temperature becomes lower than Temperature .
When the discharge temperature becomes lower than Temperature , the control of the control of
the compressor frequency is released.
When the discharge temperature becomes higher than Temperature ,the compressor is stopped
and the indoor unit LED starts blinking.
(Table19 : Discharge Temperature Over Rise Prevension Control / Release Temperature)
Temperature Temperature Temperature
2. CURRENT RELEASE CONTROL
The compressor frequency is controlled so that the outdoor unit input current does not exceeds
the current limit velue that was set up with the outdoor temperature.
The compressor frequency returns to the designated frequency of the indoor unit at the time
when the frequency becomes lower than the release value.
(Table20 : Current Release Operation Value / Release Value)
01-16
[ Heating ]
OT (Control / Release)
10.0A/ 9.5A
11.5A/ 11.0A
13.0A/ 12.5A
13.0A/ 12.5A
11.0A/ 10.5A
13.0A/ 12.5A
15.0A/ 14.5A
15.0A/14.5A
62.6°F(17°C)
53.6°F(12°C)
OT : Outdoor Temperature
41°F(5°C)
62.6°F(17°C)
53.6°F(12°C)
41°F(5°C)
ASU18RLF
OT (Control / Release)
OT : Outdoor Temperature
ASU24RLF
OT (Control / Release)
10.0A/ 9.5A
12.5A/ 12.0A
12.5A/ 12.0A
10.0A/ 9.5A
13.0A/ 12.5A
14.5A/ 14.0A
114.8°F(46°C)
104°F(40°C)
114.8°F(46°C)
104°F(40°C)
OT : Outdoor Temperature
ASU18RLF
OT (Control / Release)
OT : Outdoor Temperature
ASU24RLF
[ Cooling ]
122°F(50°C) 122°F(50°C)
9.0A/ 8.5A 9.0A/ 8.5A

3. ANTIFREEZING CONTROL (Cooling and Dry mode)
The compressor frequency is decrease on cooling & dry mode when the indoor heat exchanger
temperature sensor detects the temperature lower than Temperature .
Then, the anti-freezing control is released when it becomes higher than Temperature .
(Table21 : Anti-freezing Protection Operation / Release Temperature)
4. COOLING PRESSURE OVERRISE PROTECTION
When the outdoor unit heat exchange sensor temperature rises to 152.6°F (67°C) or greater,
the compressor and the outdoor fan motor are stopped and trouble display is performed.
5. HIGH TEMPERATURE RELEASE CONTROL ( HEATING MODE )
On heating mode, the compressor frequency is controlled as following based on the
detection value of the indoor heat exchanger temperature sensor.
01-17
Indoor heat exchange
temperature
[ Control System ]
It returns to the normal operation
145.4°F
(63°C)
Outdoor temperature
Over than 50°F(10°C) *1
or 53.6°F(12°C) *2
Less than 50°F(10°C) *1
or 53.6°F(12°C) *2
*1. When the temperature rises.
*2. When the temperature drops.
39.2°F (4°C)
44.6°F (7°C)
55.4°F (13°C)
Temperature Temperature
compressor stop
131°F
(55°C)
127.4°F
(53°C)
The compressor frequency is
decreased 15rps every 120seconds.
The compressor frequency is
decreased 2rps every 120seconds. The compressor frequency is
Maintenance of status quo.
122°F
(50°C)