Mitsubishi Electric PUHZ-ZRP35VKA2 Service Manual page 33

<Abnormalities detected while unit is operating>
Check code Abnormal points and detection method
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 temperature
thermistor (TH4) exceeds 125°C or 110°C
continuously for 5 minutes.
Abnormal if condenser/evaporator
temperature thermistor (TH5) exceeds 40°C
during defrosting and discharge temperature
thermistor (TH4) exceeds 110°C.
(2) Abnormal if discharge superheat
(Cooling: TH4−TH5 / Heating: TH4–TH6)
increases.
All the conditions in A or B are detected
simultaneously for 10 minutes continu-
ously after 6 minutes past from compres-
sor start-up (including the thermostat
indication or recovery from defrosting).
U2
<Condition A>
(TH4:1102)
• Heating mode
(TH33:1132)
• When discharge superheat is less than
70:.
• When the TH6 temp is more than the
value obtained by TH7 – 5:.
• When the condensing temp of TH5 is
less than 35:.
<Condition B>
• During compressor operation (Cooling
and Heating)
• When discharge superheat is less than
80: in Cooling.
• When discharge superheat is less than
90: in Heating.
• When condensing temp of TH6 is more
than−40:. (In Cooling only.)
(3) Abnormal if comp. surface temperature
thermistor (TH33) exceeds 125°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
U3
short (217°C or more) is detected during
(TH4:5104)
compressor operation.
(TH33:5132)
(Detection is inoperative for 10 minutes
of compressor starting process and for 10
minutes after and during defrosting.)
OCH635A
Cause
1 Short cycle of indoor unit
2 Clogged filter of indoor unit
3 Decreased airflow caused by
dirt of indoor fan
4 Dirt of indoor heat exchanger
5 Locked indoor fan motor
6 Malfunction of indoor fan motor
7 Defective operation of stop
valve (Not full open)
8 Clogged or broken pipe
9 Locked outdoor fan motor
0 Malfunction of outdoor fan motor
1 Short cycle of outdoor unit
2 Dirt of outdoor heat exchanger
3 Decreased airflow caused by
defective inspection of outside
temperature thermistor
(It detects lower temperature
than actual temperature.)
4 Disconnection or contact failure
of connector (63H) on outdoor
controller board
5 Disconnection or contact failure
of 63H connection
6 Defective outdoor controller board
7 Defective action of linear
expansion valve
8 Malfunction of fan driving circuit
1 Overheated compressor
operation caused by shortage
of refrigerant
2 Defective operation of stop
valve
3 Defective thermistor
4 Defective outdoor controller
board
5 Defective action of linear
expansion valve
1 Disconnection or contact failure
of connector (TH4/TH33) on
the outdoor controller circuit
board
2 Defective thermistor
3 Defective outdoor controller
circuit board
33
judgment and action
1–6 Check indoor unit and repair defect.
7 Check if stop valve is fully open.
8 Check piping and repair defect.
9–2 Check outdoor unit and repair defect.
3 Check the detected temperature of outside
temperature thermistor on LED display.
(SW2 on A-Control Service Tool : Refer
to "10-10. FUNCTION OF SWITCHES,
CONNECTORS AND JUMPERS".)
4–6 Turn the power off and check F5 is
displayed when the power is turned on
again.
When F5 is displayed, refer to "Judgment
and action" for F5.
7 Check linear expansion valve. Refer to "10-6.
HOW TO CHECK THE PARTS".
8 Replace outdoor controller board.
1 Check intake superheat.
Check leakage of refrigerant.
Charge additional refrigerant.
2 Check if stop valve is fully open.
34 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.
5 Check linear expansion valve.
Refer to "10-6. HOW TO CHECK THE PARTS".
1 Check connection of connector (TH4/TH33) on the
outdoor controller circuit board.
Check breaking of the lead wire for thermistor (TH4/
TH33). Refer to "10-9. TEST POINT DIAGRAM".
2 Check resistance value of thermistor (TH4/TH33)
or temperature by microprocessor.
(Thermistor/TH4/TH33: Refer to "10-6. HOW
TO CHECK THE PARTS".) (SW2 on A-Control
Service Tool: Refer to "10-10. FUNCTION OF
SWITCHES, CONNECTORS AND JUMPERS".)
3 Replace outdoor controller board.