Mitsubishi Electric Mr. Slim PUZ-M200YKA2.UK Service Manual page 31

<Abnormalities detected while unit is operating>
Check Code Abnormal points and detection method
High pressure(High pressure switch 63H
operated)/High compressor temperature
(Thermal protector TRS operated)
Abnormal if high pressure switch
63H(4.15MPa) or thermal protector
TRS(130°C) operated during compressor
operation
U1
(1302)
High comp. surface temperature
Abnormal if comp. surface temperature
thermistor (TH4/TH33) exceeds 117°C or
110°C continuously for 5 minutes.
Abnormal if condenser/evaporator temperature
thermistor (TH5) exceeds 40°C during defrosting
and comp. surface temperature thermistor (TH4/
TH33) exceeds 110°C.
Abnormal if discharge superheat
( Cooling: TH4/TH33−TH6
Heating: TH4/TH33−TH5) increases.
All the conditions in A or B are detected
simultaneously for 10 minutes continu-
ously after 6 minutes past from compressor
Startup (including the thermostat indication
or recovery from defrosting).
U2
<Condition A>
(TH4:1102)
• Heating mode
(TH33:1132)
• When discharge superheat is less than 70°C.
• When the TH6 temp is more than the
value obtained by TH7−5°C.
• When the condensing temp of TH5 is
less than 35°C.
<Condition B>
• During compressor operation (Cooling
and Heating)
• When discharge superheat is less than
80°C in Cooling.
• When discharge superheat is less than
90°C in Heating.
• When condensing temp of TH6 is more
than −40°C. (In Cooling only.)
Abnormal if comp. surface temperature ther-
mistor (TH4/TH33) exceeds 117°C or 110°C
continuously for 5 minutes.
Open/short circuit of discharge
temperature thermistor (TH4)/comp.
surface thermistor (TH33)
Abnormal if open (−20°C or less) or
short (217°C or more) is detected during
compressor operation.
U3
(Detection is inoperative for 10 minutes
(TH4:5104)
of compressor starting process and for 10
(TH33:5132)
minutes after and during defrosting.)
OCH775B
Cause
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
Defective operation of stop valve
(Not full open)
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 outside
temperature thermistor
(It detects lower temperature than
actual temperature.)
Disconnection or contact failure of
connector (63H or TRS) on out-
door controller board
Disconnection or contact failure of
63H or TRS connection
Defective outdoor controller board
Defective action of linear expan-
sion valve
Malfunction of fan driving circuit
Overheated compressor operation
caused by shortage of refrigerant
Defective operation of stop valve
Overheated compressor operation
caused by shortage of refrigerant
Defective operation of stop valve
Defective thermistor
Defective outdoor controller board
Defective action of linear expan-
sion valve
Disconnection or contact failure
of connector (TH4/TH33) on the
outdoor controller circuit board
Defective thermistor
Defective outdoor controller circuit
board
31
Judgment and action
– Check indoor unit and repair defect.
Check if stop valve is fully open.
Check piping 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 "10-9. FUNCTION OF SWITCHES,
CONNECTORS AND JUMPERS".)
– Turn the power off and check if F5 is
displayed when the power is turned on
again.
When F5 is displayed, refer to
"Judgment and action" for F5.
Check linear expansion valve.
Refer to "10-5. HOW TO CHECK THE
PARTS".
Replace outdoor controller board.
Check intake superheat.
Check leakage of refrigerant.
Charge additional refrigerant.
Check if stop valve is fully open.
Check intake superheat.
Check leakage of refrigerant.
Charge additional refrigerant.
Check if stop valve is fully open.
Turn the power off and check if U3 is
displayed when the power is on again.
When U3 is displayed, refer to "Judgment
and action" for U3.
Check linear expansion valve.
Refer to "10-5. HOW TO CHECK THE
PARTS".
Check connection of connector (TH4/TH33)
on the outdoor controller circuit board. Check
breaking of the lead wire for thermistor
(TH4/TH33). Refer to "10-8. TEST POINT
DIAGRAM".
Check resistance value of thermistor (TH4/
TH33) or temperature by microprocessor.
(Thermistor/TH32: Refer to "10-5. HOW TO
CHECK THE PARTS".)(SW2 on A-Control
Service Tool: Refer to "10-9. FUNCTION
OF SWITCHES, CONNECTORS AND
JUMPERS".)
Replace outdoor controller board.