Mitsubishi Electric PUHZ-W50VHA-BS Service Manual page 47

Abnormal point and detection method
Error Code
Open/short of outdoor unit thermistors
(TH3, TH32, TH33, TH6, TH7, and TH8)
Abnormal if open or short is detected
during compressor operation.
Open detection of thermistors TH3, TH32
and TH6 is not detected for 10 seconds to
10 minutes after compressor starting and
10 minutes after and during defrosting.
Check which unit has abnormality in its
thermistor by switching the mode of SW2.
(Refer to 9-7.)
HW112, 140
Heatsink thermistor (TH8) is in the power
U4
module.
Symbol
TH3
TH32
TH33
TH6
TH7
TH8
TH8
Temperature of heatsink
Abnormal if heatsink thermistor (TH8)
detects temperature indicated below.
W50V ••••••••••••••••••• 77°C
W85V ••••••••••••••••••• 77°C
HW140VHA ••••••••••• 84°C
HW112YHA•••••••••••• 95°C
HW140YHA ••••••••••• 95°C
HW140VHA2 •••••••••• 89°C
U5
HW112YHA2 •••••••••• 95°C
HW140YHA2 •••••••••• 95°C
Power module
Check abnormality by driving power module
in case overcurrent is detected.
(UF or UP error condition)
U6
Too low superheat due to low discharge
temperature
Abnormal if discharge superheat is
continuously detected -15: or less for
3 minutes even though linear expansion
U7
valve has minimum open pulse after
compressor starts operating for 10 minutes.
Outdoor fan motor
Abnormal if rotational frequency of the fan
motor is not detected during DC fan motor
operation.
Fan motor rotational frequency is abnormal
U8
if;
• 100 rpm or below detected continuously
for 15 seconds at 20: or more outside
air temperature
• 50 rpm or below or 1500 rpm or more
detected continuously for 1 minute.
OCH439H
1 Disconnection or contact failure
of connectors
Outdoor controller circuit board:
(
TH3, TH32, TH33, TH6/TH7
Outdoor power circuit board:
CN3
2 Defective thermistor
3 Defective outdoor controller
circuit board
Thermistors
Name
Thermistor <Liquid temperature>
Thermistor <Inlet water temperature>
Thermistor <Suction pipe temperature> HW112, 140
Thermistor <Plate HEX liquid temperature>
Thermistor <Ambient temperature>
Thermistor <Heatsink temperature> W50, 85
Internal thermistor HW112, 140
1 The outdoor fan motor is
locked.
2 Failure of outdoor fan motor
3 Air flow path is clogged.
4 Ambient temperature is high.
5 Defective thermistor
6 Defective input circuit of
outdoor power circuit board
7 Failure of outdoor fan drive
circuit
1 Defective outdoor power circuit
board
2 Decrease of power supply voltage
3 Loosens, disconnection or
reverse of compressor wiring
connection
4 Defective compressor
1 Disconnection or loose
connection 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
connection of linear expansion
valve's connector
5 Defective linear expansion valve
1 Failure in the operation of the
DC fan motor
2 Failure in the outdoor circuit
controller board
Case
1 Check connection of connector (TH3, TH32,
)
2 Check resistance value of thermistor (TH3,
3 Replace outdoor controller circuit board.
12 Check outdoor fan.
3 Check air flow path for cooling.
4 Check if there is something which causes
5 Check resistance value of thermistor (TH8)
6 Replace outdoor power circuit board.
7 Replace outdoor controller circuit board.
1 Replace outdoor power circuit board.
2 Check facility of power supply.
3 Correct the wiring (U
4 Check compressor referring to 9-4.
12 Check the installation conditions of dis-
3 Check the coil of linear expansion valve.
4 Check the connection or contact of LEV-A and
5 Check linear expansion valve.
1 Check or replace the DC fan motor.
2 Check the voltage of the outdoor circuit
3 Replace the outdoor circuit controller board.
47
Judgment and action
TH33, TH6/TH7) on the outdoor controller circuit
board.
Check connection of connector (CN3) on the
outdoor power circuit board.
Check the lead wire for thermistor (TH3,
TH32, TH33, TH6, TH7, TH8). Refer to 9-6.
TH32, TH33, TH6, TH7, TH8) or check tem-
perature on LED display.
(Thermistor/TH3, TH32, TH33, TH6, TH7,
TH8: Refer to 9-5.)
(SW2: Refer to 9-7.)
Open detection Short detection
-40°C or below 90°C or above
-40°C or below 102°C or above
-40°C or below 90°C or above
-40°C or below 90°C or above
-40°C or below 90°C or above
-35°C or below 102°C or above
-35°C or below 170°C or above
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, refer to error
code U4.
or temperature by microcomputer.
(Thermistor/TH8: Refer to 9-5.)
(SW2: Refer to 9-7.)
V W phase) to
• •
compressor. Refer to 9-6 (Outdoor power
circuit board).
charge temperature thermistor (TH4).
Refer to 9-5.
LEV-B on outdoor controller circuit board.
Refer to 9-4.
controller board during operation.
(when the failure is still indicated even after
performing the remedy 1 above.)