Mitsubishi Electric PUHZ-P200YKA.UK, Service Manual

Page: 33 / 102

33
Check Code Abnormal points and detection method Case Judgment and action
U4
(TH3:5105)
(TH6:5107)
(TH7:5106)
(TH8:5110)
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.
Note: Check which unit has abnormality in
its thermistor by switching the mode
of SW2. (PAC-SK52ST)
(Refer to "10-10. FUNCTION OF SWITCHES,
CONNECTORS AND JUMPERS".)
1
Disconnection or contact failure of
connectors
Outdoor controller circuit
board: TH3, TH6/TH7
Outdoor power circuit board: CN3
2
Defective thermistor
3
Defective outdoor controller circuit
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
"10-9. TEST POINT DIAGRAM"
2
Check resistance value of thermistor
(TH3,TH6,TH7,TH8) or check temperature
by microprocessor. (Thermistor TH3,TH6,
TH7, TH8: Refer to "10-6. HOW TO
CHECK THE PARTS".)
(SW2 on A-Control Service Tool: Refer
to "10-10. FUNCTION OF SWITCHES,
CONNECTORS AND JUMPERS.)
3
Replace outdoor controller circuit board.
Note: Emergency operation is available
in case of abnormalities of TH3,
TH6 and TH7. Refer to "10-8.
EMERGENCY OPERATION".
U5
(4230)
Temperature of heat sink
Abnormal if heat sink thermistor (TH8)
detects temperature indicated below.
P200/250Y ········································ 90
:
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
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°C.)
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. HOW TO CHECK
THE PARTS".)
(SW2 on A-Control Service Tool: Refer
to "10-10. FUNCTION OF SWITCHES,
CONNECTORS AND JUMPERS".)
6
Replace outdoor power circuit board.
7
Replace outdoor controller circuit board.
U6
(4250)
Power module
Check abnormality by driving power module
in case overcurrent is detected.
(UF or UP error condition)
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
Open stop valve.
2
Check facility of power supply.
3
Correct the wiring (U
•
V
•
W phase) to
compressor. Refer to "10-9. TEST POINT
DIAGRAM". (Outdoor power circuit board).
4
Check compressor referring to "10-6.
HOW TO CHECK THE PARTS".
5
Replace outdoor power circuit board.
U8
(4400)
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;
• 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.
1
Failure in the operation of the
DC fan motor
2
Failure in the outdoor circuit
controller board
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.)
Thermistors
Open detection Short detection
Symbol Name
TH3
TH6
TH7
TH8
− 40
:
or below
− 40
:
or below
− 40
:
or below
− 27
:
or below
90
:
or above
90
:
or above
90
:
or above
Thermistor <Liquid>
Thermistor <2-phase pipe>
Thermistor <Ambient>
Thermistor <Heat sink>
102
:
or above
(
)
OCH582B