Carrier 40MBFAQ Service Manual page 28

40MBFAQ: Service Manual
DIAGNOSIS AND SOLUTION (CONT.)
PC 03 (High pressure protection or Low Pressure Protection Diagnosis and Solution) (CONT)
Troubleshooting
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 ?
Yes
Is the low pressure protector
broken? Method: Disconnect the
plug. Measure the low protector
resistance. If the protector is normal,
the vaule is 0.
No
Is the outdoor ambient
temperature too low?
No
Is the high pressure valve core
fully opened?
Yes
Is the indoor fan running
properly in the COOLING mode?
Yes
Replace the outdoor main board.
Is it in working order?
No
When the level of refrigerant is
insufficient, does the system function
properly after more refrigerant is added?
Reconnect the low pressure protector
No
and main control board.
Replace the low pressure protector.
Yes
Yes Stop the unit.
Open the high pressure valve
No
of the valve core.
Refer to the Fan Speed is Out of Control
No
malfunction and resolve the problem.
Check whether the refrigerant
No
system is functioning properly.
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