Carrier 40MAHB Series Service Manual page 34

40MAHB: Service Manual
DIAGNOSIS AND SOLUTION (CONT)
Low Pressure Protection (PC03)
Description: The outdoor pressure switch shuts the unit down because the low pressure is lower than 0.13 MPa and the LED displays the failure
code.
Recommended parts to repair:
• Connection wires
• Outdoor PCB
• Low pressure protector
• Refrigerant
Troubleshooting
resistance. If the protector is normal,
Is the outdoor ambient temperature
properly after more refrigerant is added?
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
Low pressure protection
Are the low pressure protector
and the main control
board wired properly?
Yes
Is the low pressure
protector broken?
Method: Disconnect the plug.
Measure the low pressure protector
the value is 0.
Does the problem still exist?
Yes
too low?
No
Is the valve core of the high
pressure valve fully opened?
Yes
Is the indoor fan running properly
in the cooling mode?
Yes
Replace the outdoor main board.
Does a problem still exist?
No
When the refrigerant level is not
sufficient, does the system function
No
Check whether the refrigerant
system is functioning properly.
Reconnect the low pressure protector and
No
the main control board.
Replace the low pressure protector.
No
Yes Stop the unit.
Open the valve core of the
No
high pressure valve.
Refer to the "Fan Speed is operating
No
outside of Normal Range" malfunction.
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