Mitsubishi Electric PUZ-WZ50VAA Service Manual page 34

Check code Abnormal points and detection method
High pressure (High pressure switch
63H operated)
Abnormal if high pressure switch 63H
operated (3.2 MPa) during compressor
operation.
63H: High pressure switch (INV)
63L: High pressure switch (FIX)
U1
(INV:1302
FIX:1402)
High discharge temperature
(1) Abnormal if TH4 exceeds 125
°C
110 continuously for 5 minutes.
Abnormal if TH4 exceeds 110
more continuously for 30 seconds after
90 seconds have passed since the
defrosting operation started.
(2) Abnormal if discharge superheat
(Cooling: TH4−TH6 /
Heating: TH4−T63HS)
°C
exceeds 70
minutes.
TH4: Thermistor <Discharge>
temperature
TH6: Thermistor <2-phase temp.>
temperature
U2
T63HS: Plate HEX cond./eva.
(INV:1102
temperature
FIX:1232)
High comp. surface temperature
Abnormal if TH33 exceeds 120°C.
In the case of high comp. surface
temperature error, compressor does
not restart unless the thermistor (TH33)
becomes less than 95°C.
TH33: Thermistor <Comp. surface>
High comp. surface temperature of
Fixed speed compressor
Abnormal if inner protector exceeds
160°C. surface temperature error,
compressor does not restart unless the
inner protector becomes less than 90°C.
Inner protector: protective device
internally mounted in Fixed speed
compressor.
Open/short circuit of outdoor unit
temperature thermistor (TH4, TH33)
Abnormal if open (-20
°C
short (217 or more) is detected during
compressor operation.
(Detection is inoperative for 10 minutes
U3
of compressor starting process and for 10
(5104)
minutes after and during defrosting.)
TH4: Thermistor <Discharge>
TH33: Thermistor <Comp. surface>
OCH816
Short cycle of indoor unit
Clogged filter of indoor unit
Decreased airflow caused by
dirt of indoor fan
Dirt of indoor heat exchanger
Locked indoor fan motor
Malfunction of indoor fan motor
Clogged or broken pipe
Locked outdoor fan motor
Malfunction of outdoor fan
motor
Short cycle of outdoor unit
Dirt of outdoor heat exchanger
Decreased airflow caused by
defective inspection of out-
side temperature thermistor (It
detects lower temperature than
actual temperature.)
Disconnection or contact failure
of connector (63H/63L) on out-
door controller board
Disconnection or contact failure
of 63H/63L connection
Defective outdoor controller
board
Defective action of linear
expansion valve
Malfunction of fan driving circuit
Overheated compressor
°C
operation caused by shortage
or
of refrigerant
Defective thermistor
°C
or
Defective outdoor controller
board
Defective action of linear
expansion valve
Clogging with foreign objects in
continuously for 10
refrigerant circuit
Note: Clogging occur in the
In the case of the unit does not
restart:
Detection temp. of thermistor
(TH33) ≥ 95°C
Disconnection or contact failure
of connectors (TH4, TH33) on
°C the outdoor controller circuit
or less) or
board
Defective thermistor
Defective outdoor controller cir-
cuit board
Cause
parts which become below
freezing point when water
enters in refrigerant circuit.
34
judgment and action
– Check indoor unit and repair defect.
Check outdoor unit and repair defect.
Check outdoor unit and repair defect.
– Check outdoor unit and repair defect.
Check the detected temperature of outside
temperature thermistor on LED display. (SW2
on A-Control Service Tool: Refer to "9-7.
FUNCTION OF SWITCHES, CONNECTORS
AND JUMPERS".)
– Turn the power off and check F5 is dis-
played when the power is turned again.
When F5 is displayed, refer to "Judgment
and action" for F5.
Check linear expansion valve. Refer to "9-4.
HOW TO CHECK THE PARTS".
Replace outdoor controller board.
Check intake superheat.
Check leakage of refrigerant.
Turn the power off and check if U3 is dis-
played when the power is turned on again.
When U3 is displayed, refer to "Judgment
and action" for U3.
Check linear expansion valve.
Refer to "9-4. HOW TO CHECK THE PARTS"
After recovering refrigerant, remove water
from entire refrigerant circuit under vacuum
more than 1 hour.
Check connection of connector (TH4, TH33) on
the outdoor controller circuit board.
Check breaking of the lead wire for
TH4, TH33. Refer to "9-6.TEST POINT
DIAGRAM".
Check resistance value of TH4, TH33 or
temperature by microprocessor.
(Thermistor/TH4, TH33: Refer to "9-4. HOW
TO CHECK THE PARTS".) (SW2 on A-Control
Service Tool: Refer to "9-7. FUNCTION OF
SWITCHES, CONNECTORS AND JUMPERS".)
Replace outdoor controller board.