Open/Short Circuit Of Discharge Temperature Thermistor (Th4); Open/Short Of Outdoor Unit Thermistors; Temperature Of Heatsink; Power Module - Mitsubishi Electric Mr.Slim PUHZ-RP35VHA3 Service Manual

Abnormal points and detection method
Error Code
Open/short circuit of discharge
temperature thermistor (TH4)
Abnormal if open (3: or less) or short
(217: or more) is detected during
U3
compressor operation.
(5104)
(Detection is inoperative for 10 minutes of
compressor starting process and for 10
minutes after and during defrosting.)

Open/short of outdoor unit thermistors

(TH3, TH6, TH7, and TH8)
Abnormal if open or short is detected
during compressor operation.
Open detection of thermistors TH3 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
U4
SW2. (PAC-SK52ST)
(TH3:5105)
(Refer to 11-10.)
(TH6:5107)
(TH7:5106)
(TH8:5110)
Symbol
TH3
TH6
TH7
TH8
TH8

Temperature of heatsink

Abnormal if heatsink thermistor(TH8)
detects temperature indicated below.
RP35/ 50··········································· 84:
RP60/ 71VHA2 ································· 77:
RP60/ 71VHA2
1
RP60/ 71VHA3 ································· 84:
RP100VHA2 /VHA3 ························ 77:
(1)
U5
RP125/140VHA2
(4230)
RP100-140YHA2

Power module

Check abnormality by driving power module
in case overcurrent is detected.
(UF or UP error condition)
U6
(4250)
Too low superheat due to low discharge
temperature
Abnormal if discharge superheat is
continuously detected less than or equal
to -15: for 3 minutes even though linear
U7
expansion valve has minimum open pulse
(1520)
after compressor starts operating for 10
minutes.
1 Disconnection or contact
2 Defective thermistor
3 Defective outdoor controller
1 Disconnection or contact failure
(
2 Defective thermistor
3 Defective outdoor controller
Thermistors
Name
Thermistor <Outdoor pipe>
Thermistor <Outdoor 2-phase pipe>
Thermistor <Outdoor>
Thermistor <Heatsink> RP35-140V
Internal thermistor RP100-140Y
1 The outdoor fan motor is
2 Failure of outdoor fan motor
3 Air flow path is clogged.
4 Rise of ambient temperature
································ 84:
5 Defective thermistor
6 Defective input circuit of
···························· 84:
7 Failure of outdoor fan drive
(1)
/YHA3 ················· 95:
(1)
1 Outdoor stop valve is closed.
2 Decrease of power supply voltage
3 Looseness, disconnection or
4 Defective compressor
5 Defective outdoor power circuit
1 Disconnection or loose
2 Defective holder of discharge
3 Disconnection or loose connection
4 Disconnection or loose
5 Defective linear expansion valve
Case
failure of connector (TH4) on
the outdoor controller circuit
board
circuit board
of connectors
Outdoor controller circuit )
board: TH3,TH6/TH7
Outdoor power circuit board:
CN3
circuit board
locked.
outdoor power circuit board
circuit
converse of compressor wiring
connection
board
connection of discharge
temperature thermistor (TH4)
temperature thermistor
of linear expansion valve's coil
connection of linear expansion
valve's connector
50
Judgment and action
1 Check connection of connector (TH4) on the
outdoor controller circuit board.
Check breaking of the lead wire for
thermistor (TH4). Refer to 11-9.
2 Check resistance value of thermistor (TH4) or
temperature by microcomputer.
(Thermistor/TH4: Refer to 11-6.)
(SW2 on A-Control Service Tool: Refer to 11-10.)
3 Replace outdoor controller board.
1 Check connection of connector (TH3,TH6/TH7)
on the outdoor controller circuit board.
Check connection of connector (CN3) on the
outdoor power circuit board.
Check breaking of the lead wire for thermistor
(TH3,TH6,TH7,TH8). Refer to 11-9.
2 Check resistance value of thermistor
(TH3,TH6,TH7,TH8) or check temperature by
microcomputer.
(Thermistor/TH3,TH6,TH7,TH8: Refer to 11-6.)
(SW2 on A-Control Service Tool: Refer to 11-10.)
3 Replace outdoor controller circuit board.
WEmergency operation is available in case of
abnormalities of TH3, TH6 and TH7.
Refer to 11-8.
Open detection Short detection
– 40: or below 90: or above
– 40: or below 90: or above
– 40: or below 90: or above
– 27: or below 102: or above
– 35: or below 170: or above
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:.)
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 11-6.)
(SW2 on A-Control Service Tool: Refer to 11-10.)
6 Replace outdoor power circuit board.
7 Replace outdoor controller circuit board.
1 Open stop valve.
2 Check facility of power supply.
3 Correct the wiring (U V W phase) to
• •
compressor. Refer to 11-9 (Outdoor power
circuit board).
4 Check compressor referring to 11-6.
5 Replace outdoor power circuit board.
12 Check the installation conditions of
discharge temperature thermistor (TH4).
3 Check the coil of linear expansion valve.
Refer to 11-7.
4 Check the connection or contact of LEV-A and
LEV-B on outdoor controller circuit board.
5 Check linear expansion valve.
Refer to 11-6.