Mitsubishi Electric PUZ-SM100VKA2 Service Manual page 31

<Abnormalities detected while unit is operating>
Abnormal points and detection method
Check code
High pressure (High pressure switch
63H operated)
Abnormal if high pressure switch 63H
(4.15MPa) operated during compressor
operation.
U1
(1302)
High discharging temperature
High comp. surface temperature
1. Abnormal if discharge thermistor (TH4)
exceeds 115°C or 110°C continuously for 5
minutes.
Abnormal if condenser/evaporator
temperature thermistor (TH5) exceeds 40°C
during defrosting and discharge thermistor
(TH4) exceeds 110°C.
2. Abnormal if discharge superheat
(TH4 - TH5) increases.
All the conditions are detected simul-
U2
taneously for 10 minutes continuously
(TH4: 1102)
after 6 minutes past from compressor
(TH33: 1132)
startup (including the thermostat indica-
tion or recovery from defrosting).
• During compressor operation (in
Cooling only)
• When discharge superheat is less than
80°C in Cooling.
• When condensing temp of TH6 is
more than -40°C. (In Cooling only.)
3. Abnormal if comp. surface temperature
thermistor (TH33) exceeds 115°C or
110°C continuously for 5 minutes.
Open/short circuit of discharge
thermistor (TH4) / comp. surface
thermistor (TH33)
Abnormal if open (TH4: −20°C or less,
TH33: −20°C or less) or short (217°C
or more) is detected during compressor
U3
operation.
(TH4: 5104)
(Detection is inoperative for 10 minutes of
(TH33: 5132)
compressor starting process.)
OCH774A
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) on outdoor
controller board
Disconnection or contact failure
of 63H connection
Defective outdoor controller board
Defective action of linear
expansion valve
Malfunction of fan driving circuit
Overheated compressor
operation caused by shortage
of refrigerant
Defective operation of stop
valve
Defective thermistor
Defective outdoor controller
board
Defective action of linear
expansion 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 "9-9. FUNCTION OF SWITCHES,
CONNECTORS AND JUMPERS".)
– Turn the power off and check F5 is
displayed when the power is turned
again.
When F5 is displayed, refer to "Judgment
and action" for F5.
Check linear expansion valve.
Refer to "9-5. 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.
Turn the power off and check if U3 is
displayed when the power is on again.
When U3 is displayed, refer to
"Judgement and action" for U3.
Check linear expansion valve.
Refer to "9-5. 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 "9-8. TEST
POINT DIAGRAM".
Check resistance value of thermistor (TH4/
TH33) or temperature by microprocessor.
(Thermistor/TH4/TH33: Refer to"9-5. HOW
TO CHECK THE PARTS".)
(SW2 on A-Control Service Tool: Refer
to "9-9. FUNCTION OF SWITCHES,
CONNECTORS AND JUMPERS".)
Replace outdoor controller board.