12. Troubleshooting
Check the basic items first to judge if the problem was caused by breakdown or misuse. If none of the basic items are related to the
problem, please scrutinize the machine according to the ‘Breakdown Diagnosis by Symptoms’ method.
12-1 Basic Breakdown Diagnosis Items
1.
The input voltage should be rating voltage ±10% range.
The airconditioner may not operate properly if the voltage is out of this range.
2.
Is the link cable linking the indoor unit and the outdoor unit linked properly?
Check the terminals if the indoor unit and outdoor unit are properly linked by the same number of cables.
Otherwise the airconditioner may not operate properly.
3.
When a problem occurs due to the contents illustrated in the table below it is a symptom not related to the malfunction of the
airconditioner.
No
Operation of air conditioner
Explanation
1
The OPERATION indication LED(GREEN) blinks when a
power plug of the indoor unit is plugged in for the first time.
It indicates power is on. The LED stops blinking if the operation
ON/OFF button on the remote control unit is pushed.
2
In a COOL operation mode, the compressor does not
operate at a room temperature higher than the setting
temperature that the INDOOR FAN should operate.
In a HEAT operation mode, the compressor does not operate
at a room temperature lower than the setting temperature
that indoor fan should operate.
In happens after a delay of 3 minutes when the compressor
is reoperated. The same phenomenon occurs when a power
is on.
As a phenomenon that the compressor is reoperated after a
delay of 3 minutes, the indoor fan is adjusted automatically
with reference to a temperature of the air blew.
3
Fan speed setting is not allowed in DRY(
4
Compressor stops operation intermittently in DRY(
5
Compressor of the outdoor unit is operating although it is
turned off in a HEAT mode.
When the unit is turned off while de-ice is activated,
the compressor continues operation for up to 9 minutes
(maximum) until the deice is completed.
6
Timer LED(GREEN) of the indoor unit lights up and the
air conditioner does not operate.
Timer is being activated and the unit is in ready mode.
The unit operates normally if the timer operation is cancelled.
7
The compressor and indoor fan stop intermittently in
HEAT mode.
The compressor and indoor fan stop intermittently if room
temperature exceeds a setting temperature in order to protect
the compressor from overheated air in a HEAT mode.
8
Indoor fan and outdoor fan stop operation intermittently
in a HEAT mode.
The compressor operates in a reverse cycle to remove
exterior ice in a HEAT mode, and indoor fan and outdoor fan
do not operate intermittently for within 20% of the total heater
operation
9
The compressor stops intermittently in a COOL mode or
DRY mode, and fan speed of the indoor unit decreases.
The compressor stops intermittently or the fan speed of the
indoor unit decreases to prevent inside/outside air frozen
depending on the inside/outside air temperature.
Samsung Electronics
The speed of the indoor fan is set to LL in DRY mode.
Fan speed is selected automatically in AUTO mode.
) mode.
) mode.
Compressor operation is controlled automatically in DRY
mode depending on the room temperature and humidity.
12-1
12-2 Trouble check in the initial status
12-2-1 Diagnosis and marking of the part in trouble.
MC24F3A(B)NXAX(XAP)/MC12F3A(B)NXAX(XAP)/MC18F2A(B)NXAX(XAP)/MC12F2NXAX(XAP)/
MC09F3ANXSS/MC06F3ANXSS/MC09F2ANXSS
LAMP
Description
OPERATION
TIMER
TURBO
Indoor unit room temperature sensor error
(open or short)
Indoor unit heat exchanger temperature sensor error
(open or short)
Indoor fan motor mal function
EEPROM error
Option error
(option wasn’t set up or option data error)
Outdoor error(sensor)
Communication error
Simultanious operation error(cool, heat)
: Lamp on
: Lamp off
: Lamp flickering
MH24F3A(B)NHAC/MH12F3A(B)NHAC/MH12F2A(B)NHAC/MH16F2A(B)NXAX/MH12F2ANXAX
LAMP
Description
OPERATION
TIMER
TURBO
Indoor unit room temperature sensor error
(open or short)
Indoor unit heat exchanger temperature sensor error
(open or short)
Indoor fan motor mal function
EEPROM error
Option error
(option wasn’t set up or option data error)
Outdoor error(sensor)
Communication error
Cooling/Heating Confusion Error (MH12F3ANHAC ONLY)
: Lamp on
12-2
: Lamp off
: Lamp flickering
Samsung Electronics
Troubleshooting
12-2-2 Operation with abnormal motion
No
1
2
Abnormal condition
No response from
the remote control
operation signal.
Unable to operate the
outdoor unit
(MCmodel only)
Samsung Electronics
Inspection
• Plug out and plug in 5
seconds later.
• Press the TURBO button with
the remote control.
• In 3 minutes, check the
voltage between the indoor
unit terminal block N1 and 1.
Initial Diagnosis
Able to operate the
remote control.
OK
Unable to operate
the remote control.
Press the button in the indoor unit.
• If it operates, the remote control and
indoor unit receiver are in trouble.
• If not, the indoor unit is in trouble.
AC200V ~ AC240V
Problem with the outdoor unit or PCB
No power source
displayed.
Problem with the relay (RY71) or PCB
12-3
12-3 Fault Diagnosis by Symptom
12-3-1 No Power (completely dead)-Initial diagnosis
1. Checklist :
1) Is input voltage normal?
2) Is AC power linked correctly?
3) Is input voltage of DC regulator IC KA7805 of indoor unit PCB normal? (11.8Vdc~12.2Vdc)
4) Is output voltage of DC regulator IC KA780 of indoor unit PCB normal? (4.5Vdc-5.5Vdc)
2. Troubleshooting procedure
Unplug the power cord and
plug it after 5 seconds
Press the
Power Button on the
remote control unit to operate the
air conditioner
operate
Check the display board
does not operate
Check the indoor unit
control board
Yes
Check whether
2 wires of power cord are
connected correctly to the
terminal block and
control board.
No
Reconnect wires correctly
Yes
Check whether
the fuse on the control board is normal.
F701 : 3.15(2.5)[A]/250[V]
No
Replace fuse
Yes
Check the output of
SMPS on the control board.
Input power: AC230±15%[V]
KA7805 IC Input: DC12[V]
KA7805 IC output: DC5[V]
No
Replace the control board
Yes
 Check the setting temperature
12-4
Samsung Electronics
Troubleshooting
12-3-2 When the Indoor Unit Fan Does Not Operate. (Initial Diagnosis)
1. Checklist :
1) Is the indoor unit fan motor properly connected with the connector (CN72)?
2) Is the AC voltage correct?
3) Is HALL IC in indoor fan motor properly connected with the connector (CN44)?
4) Is the running capacitor (CR71) properly connected with PCB board?
2. Troubleshooting procedure
After unplugging out the power cord should
be reconnected within 5 seconds.
Yes
No
Does the OPERATION lamp blink?
Check as in the procedure
"No power parts"
Yes
Does the Solid State Relay(SS71) work properly?
Test rod location
+
-
SS71-
SS71-
No
Micom is
out of order.
Micom
should be replaced
No
PCB is
out of order.
PCB should be replaced.
Normal
Voltage
12V
Yes
Is the supply voltage of the fan motor sufficient?
Test rod location
PCB CN72
Condition
pin #3 and #5
Fan operate
Normal
Voltage
About AC 180V
Motor Fan-Capacitor is out of order
Yes
Fan motor
is out of order.
Samsung Electronics
Replace Motor
Fan-Capacitor
Fan motor
should be replaced.
12-5
Troubleshooting
12-3-3 When the Outdoor Unit Does Not Operate. (Initial Diagnosis) : MC model only
1. Checklist :
1) Is input voltage normal?
2) Is the set temperature of the remote control higher than room temperature in COOL mode?
3) Is the POWER IN wire-power(N) linked correctly?
4) Is the outdoor unit properly connected with the TERMINAL BLOCK connecto?
2. Troubleshooting procedure
After unplugging out the power cord should be
reconnected within 5 seconds.
No
Check as in the procedure
"No Power parts"
Does the OPERATION lamp blink
Yes
Does the timer lamp blink during operation?
No
Room temperature sensor is
out of order
Yes
①
②
③
No
Is the power relay RY71 operated by adjusting
the room temperature?
Test rod location
+
-
Condition
IC04 Pin No.38
GND
RY71 ON
PCB should be checked.
Micom is
out of order.
Normal
Voltage
PCB should be checked.
DC4.8V
Yes
Is rating voltage ±10% range applied relay between
Terminal block No. N(1) and No. 1
No
Power relay is
out of order
Power relay should be
replaced.
Yes
Outdoor unit is out of order.
①
No
Yes
②
Is the room sensor normal register?
10°C
20°C
30°C
17.96kΩ
12.09kΩ
8.3kΩ
③
12-6
Samsung Electronics
Troubleshooting
12-3-4 When the UP/DOWN Louver Motor Does Not Operate. (Initial Diagnosis)
1. Checklist :
1) Is input voltage normal?
2) Is the UP/DOWN louver motor properly connected with the connector (CN61)?
2. Troubleshooting procedure
Remove power cord and plug in again in approx.
5 seconds.
Does the OPERATION lamp blink?
No
Check as in the procedure
"No Power parts".
Yes
Does operation start when
swing button of the remote control unit
pushed?
Yes
Normal
No
Voltage at pin #57~#60
of micom (IC04) change?
(Squarewave)
No
Micom (IC04) is faulty.
Yes
Voltage at pin #14~#16 of
IC06(ULN2003A) and pin #15 of IC05
change? (Squarewave)
No
Driver IC05/IC06 (ULN2003A) is faulty.
Yes
UP/DOWN louver motor is faulty.
Samsung Electronics
12-7
Troubleshooting
12-3-5 In the HEAT mode, When there is no warm air current. Check this first : MH model only
1) Is the set temperature of Remote Control lower than room temperature in Heat mode?
2) Is the Outdoor PCB properly conneted with 4 way V/V connector?
Is the Thermo off?
Yes
Change the setting temperature of
remote control.
Yes
Operate it with a heating mode
as soon as the defrosting is finished.
Yes
After 3 minutes, cooling
and heating start automatically.
No
Is the unit
in the defrosting operation?
No
Is the compressor
in 3 minutes off?
No
No
Indoor operation SW is on.
Turn the SW On.
Yes
Is much frost
in the heat exchanger?
Yes
Is the
outdoor air sensor and
outdoor heat exchanger attached
correctly?
No
Yes
Attach the
sensor correctly.
Over shortage
of the refrigerant
No
Does the
4 way valve operate
normally?
No
Is the
4 way valve connector
connected correctly?
No
Connect the connecter
correctly.
Yes
Check the resistance value
of 4 way valve coil.
NG
4-WAY valve coil error
OK
Dose the
voltage of AC 220V
apply to the connector of 4 way
valve coil during the
operation?
No
Exchange
the outdoor PCB.
Yes
Go to the next page
12-8
4 way valve main body error
Samsung Electronics
Troubleshooting
In the HEAT mode, When there is no warm air current. Check this first : MH model only (cont.)
From the previous page
Does the
EEV operate
normally?
No
No
Is much frost
in the heat exchanger?
Connect the connector.
Yes
Check the
resistance value of EEV coil.
NG
EEV coil error
OK
Yes
Is much frost
in the heat exchanger?
No
Exchange
the out PCB.
Yes
EEV main body error
Does
the outdoor fan
operate at the operation of
compressor?
Yes
The over shortage of refrigerant, Insufficient
Capacity, Load estimation error
No
Is the
outdoor fan connected
correctly?
No
Connect the connector.
Yes
Check the resistance value
of outdoor fan.
NG
Outdoor fan error
OK
Dose the
voltage of DC300V
apply to the connector of outdoor
fan during the operation of
outdoor unit?
Yes
Check the motor wire.
No
Outdoor PCB error
Samsung Electronics
12-9
Troubleshooting
12-3-6 Room temperature sensor failure
LAMP
Description
OPERATION
TIMER
TURBO
Indoor unit room temperature sensor error
(open or short)
: Lamp off
: Lamp flickering
Detach the assembly sensor from the
ASS'Y main PCB CN43 connector and measure
the sensor resistance with an ohmmeter (tester).
Is the sensor resistance value
10KΩ±3% at the room temperature
of 25˚C?
No
ASS'Y Sensor Replace
SENSOR Resistance Value : 20˚C-12.09kΩ
30˚C-8.31kΩ
35˚C-6.94kΩ
40˚C-5.83kΩ
Yes
Connect the sensor to CN43,
supply power, and measure the voltage of
#1 and #2 of the CN43 connector.
Below 0.5V?
Yes
Poor ASS'Y PCB Replace
No
Over 4.9V?
Yes
Poor ASS'Y PCB Replace
No
MICOM Error or Connector(CN43) check
12-10
Samsung Electronics
Troubleshooting
12-3-7 Room Pipe sensor failure
LAMP
OPERATION
Description
TIMER
TURBO
Indoor unit heat exchanger temperature sensor error
(open or short)
: Lamp off
: Lamp flickering
1. Check the assembly condition of the sensor connector(CN43) on the indoor unit Main PCB and if not assembled, reassemble
the connector accurately.
2. Detach the room pipe sensor connector(CN43) and check the resistance between Pin #3 and #4.
Temperature(˚C)
Resistance Value(Kohm)
Temperature(˚C)
Resistance Value(Kohm)
15
14.68
30
8.31
20
12.09
35
6.94
25
10
40
5.83
Others
The data tolerance
is ±3%.
If the above data is not met, replace the room pipe sensor.
3. Assemble the room pipe sensor to PCB, plug in, and check the voltage of connector 3 and 4. If the resistance is below 0.5V or
over 4.9V, replace the indoor Main PCB. (short or disconnected in the PCB board)
Samsung Electronics
12-11
Troubleshooting
12-3-8 When the remote control is not receiving.
1. Check the connector was normally assembled.
2. Put the set in operation and check the valtage of Vout(+) and Gnd(-) of thr RM01 while operating the remote control.
When the voltage descends below 3V, the assembly module PCB is ormal and the main PCB is poor.
Then replace the main PCB.
12-12
Samsung Electronics
12-4 PCB Inspection Method
12-4-1 Pre-inspection Notices
1. Check if you pulled out the AC power plug when you eliminate the PCB or front panel.
2. Don’t hold the PCB side not impose excessive force on it to eliminate the PCB.
3. Don’t pull the lead wire but hold the whole housing to connect or disconnect a connector to the PCB.
12-4-2 Inspection Procedure
1. Check connector connection and peeling of PCB or bronze coating pattern when you think the PCB is broken.
2. PCB composition
 H/P Indoor mode[MH24F3A(B)NHAC/MH12F3A(B)NHAC/MH12F2A(B)NHAC/MH16F2A(B)NXAX/MH12F2ANXAX]
• Main PCB Part : MICOM And Surrounding Circuit, Room Fan Motor Driving Circuit and Control Circuit, Sensor Driving Circuit,
Power Circuit Of DC12V Aand DC5V, and Buzzer Driving Circuit, Blade Driving Circuit.
• Sub PCB Part : AC communication circuit
• Display PCB Part : LED Lamp Display, Room Adderss Setting Circuit, Remocon Module, Switch
 C/O Indoor model(MC24F3A(B)NXAX(XAP)/MC12F3A(B)NXAX(XAP)/MC18F2A(B)NXAX(XAP)/MC12F2NXAX(XAP)/
MC09F3A(B)NXSS/MC06F3A(B)NXSS/MC09F2A(B)NXSS]
• POWER PCB Part : Relay, Room Fan Motor Driving Circuit And Control Circuit, Power Circuit Of Dc12v And DC5V,
and Buzzer Driving Circuit
• Main PCB Part : MICOM and Surrounding Circuit, LED Lamp, Sensor Driving Circuit, Switch
 H/P Outdoor model [MH48F3A(B)XHAC / MH24F2A(B)XHAC / MH32F2A(B)XXAX / MH24F2AXXAX]
• Main PCB Part : MICOM And Surrounding Circuit, Outdoor AC Load (Compressor, Fan Motor, Bypass Valve, 4 way Valve) Driving
Circuit, Eev Driving Part, Power Circuit Of DC 12V And DC 5V, Sensor Driving Circuit, Data Display Circuit,
Ac Communication Circuit
 C/O Outdoor model [MC48F3A(B)XXAX(XAP) / MC20F3A(B)XXSS]
• Main PCB Part : MICOM and Surrounding Circuit, Outdoor AC load (Compressor, Fan Motor, Bypass Valve, Solenoid Valve)
Driving Circuit, Power Circuit of DC12V and DC 5V, Sensor Driving Circuit, Indoor Comp Singal Receive Circuit
Samsung Electronics
12-13
Troubleshooting
12-4-3 Detailed Inspection Procedure
 H/P Indoor model [MH24F3A(B)NHAC / MH12F3A(B)NHAC / MH12F2A(B)NHAC / MH16F2A(B)NXAX / MH12F2ANXAX]
No
Procedure
Inspection Method
Cause
1
Plug out and pull the PCB
out of the electronic box.
Check the PCB fuse.
1) Is the fuse disconnected?
- Over current
- Indoor fan motor short
- AC part pattern short of the main PCB
2
Supply power.
If the operation lamp
twinkles at this time,
1) ~ 4) no relation.
1) Is the BD71 input voltage AC200V ~ AC240V?
- Power Cord is fault, Fuse Open, Wrong Power
- Cable Wiring, AC Part is faulty
- Choke Coil (FT71) is fault
2) Is the voltage between both terminals of the
C101about DC 310V?
- Bridge Diode (BD71) is faulty
3) Is the voltage between both terminals of the
C103 on the second side of the switching transformer (ST11) about DC 12V?
- Switching Transformer or Power circuit is faulty
4) Is the voltage between both terminals of OUT
and GND of IC04(KA78L05) about DC 5V?
- Regulator IC (IC02) or Power circuit is faulty
1) Is the voltage over AC180V being imposed
on the terminal #3 and #5 of the fan motor
connector(CN72)
- SSR(SS71) is faulty
- Micom is out of order
- Communication between indoor and outdoor
is faulty
3
Press the ON/OFF button
1. Fan mode on
 C/O Indoor model [MC24F3A(B)NXAX(XAP)/MC12F3A(B)NXAX(XAP)/MC18F2A(B)NXAX(XAP)/MC12F2NXAX(XAP)
MC09F3A(B)NXSS/MC06F3A(B)NXSS/MC09F2A(B)NXSS]
No
Procedure
Inspection Method
Cause
1
Plug out and pull the PCB
out of the electronic box.
Check the PCB fuse.
1) Is the fuse disconnected?
- Over current
- Indoor fan motor short
- AC part pattern short of the main PCB
2
Supply power.
If the operation lamp
twinkles at this time,
1) ~ 4) no relation.
1) Is the BD71 input voltage AC200V ~ AC240V?
- Power Cord is fault, Fuse Open, Wrong Power
- Cable Wiring, AC Part is faulty
- Choke Coil (FT71) is fault
2) Is the voltage between both terminals of the
C101 about DC 310V?
- Bridge Diode (BD71) is faulty
3) Is the voltage between both terminals of the
C103 on the second side of the switching transformer (ST11) about DC 12V?
- Switching Transformer or Power circuit is faulty
4) Is the voltage between both terminals of OUT
and GND of IC04(KA78L05) about DC 5V?
- Regulator IC (IC02) or Power circuit is faulty
1) Is the voltage over AC180V being imposed
on the terminal #3 and #5 of the fan motor
connector(CN72)
- SSR(SS71) is faulty
- Micom is out of order
2) Check the voltage of both terminals of indoor
terminal block N and C after 3 minutes operation
: AC 220V
- RY71 is faulty
- Connection is faulty
3
12-14
Press the ON/OFF button
1. Cooling mode on
(setting temp. must
be higher than indoor
temp.)
Samsung Electronics
Troubleshooting
Detailed Inspection Procedure(cont.)
 H/P Outdoor model [MH48F3A(B)XHAC / MH24F2A(B)XHAC / MH32F2A(B)XXAX / MH24F2AXXAX]
No
Procedure
Inspection Method
Cause
1
Plug out and pull the PCB
out of the electronic box.
Check the PCB fuse.
1) Is the fuse disconnected?
- Over current
- Indoor fan motor short
- AC part pattern short of the main PCB
2
Supply power.
If the 7-segment display
at this time,
1) ~ 4) no relation.
1) Is the voltage between both terminals #1 and #3
of the transformer input connector(GT-2) voltage
AC200V ~ AC240V?
- Over current
- Indoor fan motor short
- AC part pattern short of the main PCB
1) Is the voltage between both terminals #1 and #3
of the transformer input connector(GT-2) voltage
AC200V ~ AC240V?
- Transformer is faulty
3) Is the voltage between 12V line and ground line
that marked on the PCB about 12V?
- Fuse Open
- Regulator IC KA7812(IC01) or Power circuit is
faulty
4) Is the voltage between 5V line and ground line
that marked on the PCB about 5V?
- Regulator IC KA7805(IC02) or Power circuit is
faulty
 C/O Outdoor model [MC48F3A(B)XXAX(XAP) / MC20F3A(B)XXSS]
No
Procedure
Inspection Method
Cause
1
Plug out and pull the PCB
out of the electronic box.
Check the PCB fuse.
1) Is the fuse disconnected?
- Over current
- Indoor fan motor short
- AC part pattern short of the main PCB
2
Supply power.
If the 7-segment display
at this time,
1) ~ 4) no relation.
1) Is the voltage between both terminals #1 and #3
of the transformer input connector(GT-2) voltage
AC200V ~ AC240V?
- Power Cord is fault, Fuse Open, Wrong Power
- Cable Wiring, AC Part is faulty
2) Is the voltage between both terminals #1 and
#3 of the transformer output connector(CN11)
voltage AC17V ~ AC19V?
- Transformer is faulty
3) Is the voltage between 12V line and ground line
that marked on the PCB about 12V?
- Fuse Open
- Regulator IC KA7812(IC01) or Power circuit is
faulty
4) Is the voltage between 5V line and ground line
that marked on the PCB about 5V?
- Regulator IC KA7805(IC02) or Power circuit is
faulty
Samsung Electronics
12-15
12-4-4 Temperature Sensor Feature Conversion Table(Room Temperature Sensor); 103AT
Temperature Sensor Resistance Temperature Sensor Resistance Temperature Sensor Resistance Temperature Sensor Resistance
[˚C]
[Kohm]
[˚C]
[Kohm]
[˚C]
[Kohm]
[˚C]
[Kohm]
70
69
68
67
66
65
64
63
62
61
60
2.229
2.296
2.365
2.437
2.512
2.589
2.669
2.752
2.838
2.928
3.021
49
48
47
46
45
44
43
42
41
40
4.300
4.444
4.594
4.749
4.912
5.080
5.256
5.439
5.630
5.828
29
28
27
26
25
24
23
22
21
20
8.622
8.944
9.281
9.632
10
10.380
10.780
11.200
11.630
12.090
9
8
7
6
5
4
3
2
1
0
18.700
19.480
20.290
21.150
22.050
22.990
23.900
25.030
26.130
27.280
59
58
57
56
55
54
53
52
51
50
3.116
3.216
3.319
3.426
3.537
3.652
3.772
3.897
4.026
4.161
39
38
37
36
35
34
33
32
31
30
6.033
6.246
6.468
6.699
6.941
7.192
7.455
7.729
8.015
8.313
19
18
17
16
15
14
13
12
11
10
12.560
13.060
13.570
14.120
14.680
15.280
15.900
16.550
17.240
17.960
-1
-2
-3
-4
-5
-6
-7
-8
-9
28.470
29.720
31.040
32.430
33.890
35.430
37.050
38.760
40.560
Temperature Sensor Characteristic Curve
Temperature
(˚C)
70
60
50
40
30
At the temperature of 25˚C(10KΩ)
20
10
0
-10
-9
5
10
15
20
25
30
35
40
Resistance Value (Kohm)
12-16
Samsung Electronics
12-5 Main Part Inspection Method
Part
Room Temperature Sensor
Room Fan Motor
Breakdown Inspection Method
Measure resistance with a tester
Normal
At the normal temperature 37kΩ~ 8.3kΩ(-7˚C~+30˚C) *Refer to Table 12-4-4.
Abnormal
∞, 0Ω . . . Open or Short
Measure the resistance between terminals of the connector (CN72) with a tester.
Abnormal
Outdoor Fan Motor
Measure resistance with a tester
Abnormal
Stepping Motor
Samsung Electronics
∞, 0Ω . . . Open or Short
∞, 0Ω . . . Open or Short
Measure the resistance between the red wire and each terminal wire with a tester.
Normal
About 300Ω at the normal temperature (20˚C ~ 30˚C)
Abnormal
∞, 0Ω . . . Open or Short
12-17