Carrier 40MBFAQ Service Manual page 27

40MBFAQ: Service Manual
DIAGNOSIS AND SOLUTION (CONT.)
PC 03 (High pressure protection or Low Pressure Protection Diagnosis and Solution)
Description: The outdoor pressure switch cuts off the system because the high pressure is higher than 4.4 MPa or the outdoor
pressure switch cuts off the system because the low pressure is lower than 0.13 MPa. In either case, the LED displays a failure
code.
Recommended parts to prepare:
• Connection wires
• Pressure switch
• Outdoor fan
• Outdoor main PCB
• Refrigerant
Troubleshooting
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
High pressure protection
Are the high pressure switch and the
main control boar wired correctly?
Yes
Is the high pressure
protector broken?
Method: Disconnect the plug.
Measure the resistance of the high
pressure protector. If the protector is
normal, the value is 0.
Does a problem still exist?
Yes
Is the outdoor ambient
temperature is higher than 50°C?
No
Ensure the outdoor unit
ventilation is good.
Yes
Is the outdoor fan running properly?
Yes
Is the heat exchanger dirty?
No
Replace outdoor main board.
Is the problem resolved?
No
Connect the high pressure switch
No
and the main control board.
No Replace high pressure protector.
Yes
Stop the unit.
Stop the unit
Ensure that the outdoor unit
NO
No
Yes
Clean the heat exchanger.
27
.