Abnormal Point And Detection Method - Mitsubishi Electric PUHZ-HRP71VHA Service Manual

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,
TH33 and TH6 is inoperative 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
U4
SW2. (PAC-SK52ST)
(TH3:5105)
(Refer to 11-10.)
(TH6:5107)
* HRP100, 125YHA(2)(R1)/
(TH7:5106)
HRP71, 100VHA2(R1, R2)
(TH8:5110)
Heatsink thermistor(TH8) is in the power
(TH32:5105)
module.
(TH33:5105)
Symbol
TH3,TH32,TH33
TH6
TH7
TH8
TH8
Temperature of heatsink
Abnormal if heatsink thermistor(TH8)
detects temperature indicated below.
HRP71V ·········································84:
HRP100V ·········································84:
HRP100Y ·········································95:
HRP125Y ·········································95:
U5
(4230)
Power module
Check abnormality by driving power module
in case overcurrent is detected.
U6
(UF or UP error condition)
(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.
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 if;
U8
• 100 rpm or below detected continuously
(4400)
for 15 seconds at 20: or more outside
air temperature.
• 50 rpm or below or 1500 rpm or more
detected continuously for 1 minute.
OCH425F
Case
1 Disconnection or contact failure
of connectors
Outdoor controller circuit board:
(
TH3, TH32, TH33, TH7/6
Outdoor power circuit board:
CN3
2 Defective thermistor
3 Defective outdoor controller
circuit board
Thermistors
Name
Thermistor <Outdoor pipe>
Thermistor <Outdoor 2-phasepipe>
Thermistor <Ambient>
Thermistor <Heatsink> HRP71,100VHA
Internal thermistor (except HRP71,100VHA)
1 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
outdoor power circuit board
7 Failure of outdoor fan drive circuit
1 Outdoor stop valve is closed.
2 Decrease of power supply voltage
3 Looseness, disconnection or converse
of compressor wiring connection
4 Defective compressor
5 Defective outdoor power circuit board
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
43
Judgment and action
1 Check connection of connector (TH3, TH32,
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 thermistor
(TH3, TH32, TH33, TH6,TH7,TH8).
Refer to 11-9.
2 Check resistance value of thermistor (TH3,
TH32, TH33, TH6,TH7,TH8) or check
temperature by microprocessor.
(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.
* Emergency operation is available in case
of abnormalities of TH3, TH32, TH33, TH6
and TH7.
Refer to 11-8.
Open detection
- 40 °C or below
- 40 °C or below
- 40 °C or below
- 27 °C or below
- 35 °C or below
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 microprocessor.
(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.
1 Check or replace the DC fan motor.
2 Check the voltage of the outdoor circuit
controller board during operation.
3 Replace the outdoor circuit controller board.
(When the failure is still indicated even after
performing the action 1 above.)
Short detection
90 °C or above
90 °C or above
90 °C or above
102 °C or above
170 °C or above