Service manual

ManualsBrandsMitsubishi ManualsDomestic AppliancesR410A

Thermistors

Open detection Short detection

Symbol Name

TH3,TH32,TH33

TH6

TH7

TH8

– 40[-40°F] or below

– 27[-17°F] or below

90[194°F] or above

102[216°F] or above

Thermistor <Outdoor pipe>

Thermistor <Outdoor 2-phase pipe>

Thermistor <Outdoor>

Thermistor <Heatsink>

Error Code Abnormal point and detection method Case Judgment and action

(4230)

Temperature of heatsink

Abnormal if heat sink thermistor(TH8)

detects temperature indicated below.

HA30, 36 ······························ 84:, 183˚F

The outdoor fan motor is locked.

2 Failure of outdoor fan motor

3 Air flow path is clogged.

4 Rise of ambient temperature

5 Defective thermistor

6 Defective input circuit of out-

door power circuit board

Failure of outdoor fan drive circuit

12 Check outdoor fan.

3 Check air flow path for cooling.

4 Check if there is something which causes

temperature rise around outdoor unit.

(Upper limit of ambient temperature is 46:

[114˚F].)

Turn off power, and on again to check if U5

is displayed within 30 minutes.

If U4 is displayed instead of U5, follow the

action to be taken for U4.

5 Check resistance value of thermistor (TH8)

or temperature by microcomputer.

(Thermistor/TH8: Refer to 10-6.)

(SW2 on A-Control Service Tool: Refer to

10-10.)

6 Replace outdoor power circuit board.

7 Replace outdoor controller circuit board.

(5104)

Open/short circuit of discharge

temperature thermistor (TH4)

Abnormal if open (3: [37˚F] or less) or

short (217: [422˚F] or more) is detected

during compressor operation.

(Detection is inoperative for 10 minutes

of compressor starting process and for 10

minutes after and during defrosting.)

1 Disconnection or contact failure

of connector (TH4) on the out

door controller circuit board

2 Defective thermistor

3 Defective outdoor controller cir-

cuit board

1 Check connection of connector (TH4) on the

outdoor controller circuit board.

Check breaking of the lead wire for thermis-

tor (TH4). Refer to 10-9.

2 Check resistance value of thermistor (TH4)

or temperature by microcomputer.

(Thermistor/TH4: Refer to 10-6.)

(SW2 on A-Control Service Tool: Refer to 10-10.)

3 Replace outdoor controller board.

U4,

TH32, TH33

(TH3:5105)

(TH6:5107)

(TH7:5106)

(TH8:5110)

Open/short of outdoor unit thermistors

(TH3, TH32, TH33, TH6, TH7, and TH8)

Abnormal if open or short is detected dur-

ing compressor operation.

Open detection of thermistors

TH3,TH32,TH33 and TH6 is inoperative for

10 seconds to 10 minutes after compressor

starting and 10 minutes after and during

defrosting.

WCheck which unit has abnormality in its

thermistor by switching the mode of SW2.

(PAC-SK52ST) (Refer to 11-10.)

1 Check connection of connector

(TH3,TH,32,TH33,TH7/6) on the outdoor

controller circuit board.

Check connection of connector (CN3) on the

outdoor power circuit board.

Check breaking of the lead wire for thermis

tor (TH3,TH32,TH33,TH6,TH7,TH8). Refer

to 10-9.

2 Check resistance value of thermistor (TH3,T

H32,TH33,TH6,TH7,TH8) or check tempera

ture by microcomputer.

(Thermistor/TH3,TH6,TH7,TH8: Refer to 10-6.)

(SW2 on A-Control Service Tool: Refer to 10-10.)

3 Replace outdoor controller circuit board.

WEmergency operation is available in case of

abnormalities of TH3,TH32,TH33,TH6 and

TH7. Refer to 10-8.

(4250)

Power module

Check abnormality by driving power mod-

ule in case overcurrent is detected.

(UF or UP error condition)

1 Outdoor stop valve is closed.

Decrease of power supply voltage

3 Looseness, disconnection or

converse of compressor wiring

connection

4 Defective compressor

5 Defective outdoor power circuit

board

1 Open stop valve.

2 Check facility of power supply.

3 Correct the wiring (U·V·W phase) to com-

pressor. Refer to 10-9 (Outdoor power circuit

board).

4 Check compressor referring to 10-6.

5 Replace outdoor power circuit board.

1 Disconnection or contact failure

of connectors

Outdoor controller circuit

board:

TH3, TH32, TH33,TH7/TH6

Outdoor power circuit board:

CN3

2 Defective thermistor

3 Defective outdoor controller cir-

cuit board

(

(1520)

Too low superheat due to low discharge

temperature

Abnormal if discharge superheat is con-

tinuously detected less than or equal to

-15˚C[5˚F] for 3 minutes even though lin-

ear expansion valve has minimum open

pulse after compressor starts operating for

10 minutes.

1 Disconnection or loose connec-

tion of discharge

temperature thermistor (TH4)

2 Defective holder of discharge

temperature thermistor

3 Disconnection or loose connection

of linear expansion valve’s coil

4 Disconnection or loose connec-

tion of linear expansion valve’s

connector

5 Defective linear expansion valve

12 Check the installation conditions of dis-

charge temperature thermistor (TH4).

3 Check the coil of linear expansion valve.

Refer to 10-7.

4 Check the connection or contact of LEV-A and

LEV-B on outdoor controller circuit board.

5 Check linear expansion valve.Refer to 10-6.