Pc 03/Pc 31(Low Pressure Protection Diagnosis And Solution) - Mars Comfort-Aire Century VCD-SA Series Service Manual

7.10 PC 03/PC 31(Low Pressure Protection Diagnosis and Solution)

Description: If the sampling voltage is not 5V, the LED displays a failure code.
Recommended parts to prepare:
• Connection wires
• Low pressure protector
• Indoor fan assembly
• Outdoor PCB
Troubleshooting and repair:
protector is normal the value is o.
Note: For certain models, outdoor PCB could not be removed separately. In this case, the outdoor electric
control box should be replaced as a whole.
Low pressure protection
Low pressure protection
Are the low pressure protector
Are the low pressure protector
and main control board wired
and main control board wired
properly?
properly?
Yes
Is the low pressure protector
Is the low pressure protector
broken?Method: Disconnect the
broken?Method: Disconnect the
plug. Measure the resistance of
plug. Measure the resistance of
the low pressure protector. If the
the low pressure protector. If the
protector is normal the value is o.
No
Is the outdoor ambient
Is the outdoor ambient
temperature too low?
temperature too low?
No
Is the valve core of the high
Is the valve core of the high
pressure valve fully opened?
pressure valve fully opened?
Yes
Is the indoor fan running
Is the indoor fan running
properly in cooling mode?
properly in cooling mode?
Yes
Replace outdoor main board
Replace outdoor main board
Is it in working order?
Is it in working order?
No
When the level of refrigerant is
When the level of refrigerant is
not sufficient, doe the system
not sufficient, doe the system
function properly after more
function properly after more
refrigerant is added?
refrigerant is added?
Troubleshooting 33

Reconnect the low pressure protector
Reconnect the low pressure protector
No
and main control board
and main control board
Replace low pressure protector
Yes
Replace low pressure protector
Yes Stop the unit
Stop the unit
Open the valve core of the high
Open the valve core of the high
No
pressure valve
pressure valve
Refer to the solution to the malfunction
Refer to the solution to the malfunction
of fan speed being out of control. Find
No
of fan speed being out of control. Find
the cause and resolve the problem.
the cause and resolve the problem.
Check whether the refrigerant
Check whether the refrigerant
No
system is functioning properly.
system is functioning properly.

Service Manual - VCDxxSA