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38MGRBQ: Service Manual
DIAGNOSIS AND SOLUTION (CONT)
P2/PC 31 (Low pressure protection) diagnosis and solution
ERROR CODE
MALFUNCTION DECISION
CONDITIONS
SUPPOSED CAUSES
Troubleshooting
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
P2/PC 31
If the sampling voltage is not 5V, the LED will display the failure.
Wiring mistake
Faulty overload protector
System block
Faulty Outdoor PCB
Low pressure protection
Low
Is the wiring between
between the low pressure
protector and main control
board is connected well?
Yes
Is the low pressure
protector broken?
Method: Disconnect the plug.
Method: Disconnect the plug.
Measure the resistance of the
Measure the resistance of the
low pressure protector. If the
low pressure protector. If the
protector is normal the value is 0.
Yes
Check whether the outdoor
Check whether the outdoor
ambient temperature is too
low
low
No
Check whether valve core
of high pressure valve is
of high p
opened
Yes
Check if the indoor fan runs
properly in the COOLING mode.
Yes
Replace outdoor main board
No
Refrigerant is low. Add more.
No
Check whether the refrigerant
system is ok
No
Tighten the connection
No
Replace the low pressure protector
Yes
Stop the unit
Fully open the high
No
pressure valve's valve core
Refer to the Fan Speed Out of
Control solution. Determine the
No
cause and solve it.
62
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