Mitsubishi Electric PUHZ-SW160YKA-BS Service Manual page 21

Check Code Abnormal points and detection method
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
U4
mode of SW2. (PAC-SK52ST) (Refer
(TH3:5105)
to "10-7. FUNCTION OF SWITCHES,
(TH6:5107)
CONNECTORS AND JUMPERS".)
(TH7:5106)
(TH8:5110)
Symbol
TH3
TH6
TH7
TH8
Temperature of heat sink
Abnormal if heat sink thermistor (TH8)
detects 90:.
U5
(4230)
Power module
Check abnormality by driving power module
in case overcurrent is detected.
(UF or UP error condition)
U6
(4250)
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.
OCH583A
Case
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
Thermistors
Name
Thermistor <Liquid>
Thermistor <2-phase pipe>
Thermistor <Ambient>
Thermistor <Heat sink>
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 Failure in the operation of the
DC fan motor
2 Failure in the outdoor circuit
controller board
21
Judgment and action
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
"10-6. 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 "10-4. HOW TO CHECK THE PARTS".)
(SW2 on A-Control Service Tool: Refer to "10-7.
FUNCTION OF SWITCHES, CONNECTORS AND
JUMPERS.)
3 Replace outdoor controller circuit board.
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
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 "10-4. HOW TO CHECK THE PARTS".)
(SW2 on A-Control Service Tool: Refer to "10-7.
FUNCTION OF SWITCHES, CONNECTORS AND
JUMPERS".)
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 "10-6. TEST POINT
DIAGRAM". (Outdoor power circuit board).
4 Check compressor referring to "10-4. HOW
TO CHECK THE PARTS".
5 Replace outdoor power circuit 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.)