Carrier DHMVHA Service Manual page 37

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DIAGNOSIS AND SOLUTION (CONT.)
Low pressure protection (PC03)
Error Code
Malfunction decision conditions
Supposed causes
Troubleshooting
When the refrigerant level is insufficient,
NOTE: For certain models, the outdoor PCB cannot be removed separately. In this case, the outdoor electric control box should be replaced as a
whole.
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
PC03
The outdoor pressure switch cuts off the system because low pressure is lower than 0.13 MPa and the
LED displays the failure code.
Connection wires
Outdoor PCB
Low Pressure protector
Refrigerant
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 resistance of the
low pressure protector. If the
protector is normal the value is 0.
Does a problem still exist?
Yes
Is the outdoor ambient
temperature 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
does the system function properly
after additional refrigerant is added?
No
Check whether the refrigerant
system is functioning properly.
Reconnect the low pressure protector and the
No
main control board.
Replace the low pressure protector.
No
Stop the unit.
Yes
Open the valve core of the high
No
pressure valve.
pressure valve
Refer to the
No
37