Temperature Of Heatsink; Abnormal If Heatsink Thermistor(Th8); Power Module; Outdoor Fan Motor - Mitsubishi Electric PUHZ-RP250YHA2 Service Manual

Abnormal point and detection method
Error Code
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 are 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 SW2.
(PAC-SK52ST)
(Refer to 10-10.)
Heatsink thermistor(TH8) is in the power
module.
U4
(TH3:5105)
(TH6:5107)
(TH7:5106)
(TH8:5110)
Symbol Name
Thermistor <Outdoor pipe>
TH3
Thermistor <Outdoor 2-phase pipe>
TH6
Thermistor <Outdoor>
TH7
Thermistor <Heatsink>
TH8

Temperature of heatsink

Abnormal if heatsink thermistor(TH8)

detects temperature 95 .
Heatsink thermistor is in the power mod-
ule.
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

The outdoor fan motor is considered to be
abnormal if the rotational frequency of fan
motor is abnormal when detected during
operation.
U8 Fan motor rotational frequency is abnormal if;
(4400) • 100 rpm or below detected continuously
for 15 seconds at 20
air temperature.
• 50 rpm or below or 1500 rpm or more
detected continuously for 1 minute.
Disconnection or contact failure
of connectors
Outdoor controller circuit
(
board: TH3,TH7/6
Defective thermistor
Defective outdoor controller
circuit board
Defective outdoor power circuit
board (TH8 open/ short)
Thermistors
The outdoor fan motor is
locked.
Failure of outdoor fan motor
Air flow path is clogged.
Rise of ambient temperature
Defective thermistor
Defective input circuit of
outdoor power circuit board
Failure of outdoor fan drive circuit
Outdoor stop valve is closed.
Decrease of power supply voltage
Looseness, disconnection or
converse of compressor wiring
connection
Defective compressor
Defective outdoor power circuit
board
Failure in the operation of
the DC fan motor
Failure in the outdoor circuit
controller board
or more outside
31
Case
Check connection of connector (TH3,TH7/6) on
the outdoor controller circuit board.
) Check breaking of the lead wire for thermistor
(TH3,TH6,TH7). Refer to 10-9.
Check resistance value of thermistor
(TH3,TH6,TH7) or check temperature by
microcomputer.
(Thermistor/TH3,TH6,TH7 : Refer to 10-7.)
(SW2 on A-Control Service Tool:
Refer to 10-10.)
Replace outdoor controller circuit board.
Replace outdoor power circuit board.
Emergency operation is available in case of
abnormalities of TH3, TH6 and TH7.
Refer to 10-8.
Open detection
– 40 or below
– 40 or below
– 40 or below
– 35 or below
Check outdoor fan.
Check air flow path for cooling.
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.
Check temperature(TH8) by microcomputer.
(SW2 on A-Control Service Tool: Refer to
10-10.)
Replace outdoor power circuit board.
Replace outdoor controller circuit board.
Open stop valve.
Check facility of power supply.
Correct the wiring (U·V·W phase) to
compressor. Refer to 10-9 (Outdoor power
circuit board).
Check compressor referring to 10-6.
Replace outdoor power circuit board.
Check or replace the DC fan motor.
Check the voltage of the outdoor circuit
controller board during operation.
Replace the outdoor circuit controller
board. (When the failure is still indicated
even after performing the remedy
above.)
Judgment and action
Short detection
90 or above
90 or above
90 or above
170 or above