Carrier 40MBDAQ - Page 41

40MBDAQ: Service Manual
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
41
DIAGNOSIS AND SOLUTION (CONT)
J5 (High pressure protection)
Description: If the sampling voltage is not 5V, the LED displays a failure code.
Recommended parts to prepare:
• Wiring
• Overload protector
• Outdoor PCB
Troubleshooting
High pressure protection
Are the
high pressure switch
and main control board
wired correctly?
Connect the high pressure switch
and the main control board.
Check the high pressure protector. 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?
Check the outdoor ambient temperature.
YES
Replace the high pressure protector.
NO
Is it higher than
122°F (50°C)?
Stop the unit.YES
Verify if the outdoor unit
ventilation is good.
NO
Is it good?
Ensure that the outdoor
unit ventilation is
functioning properly.
NO
Check the outdoor fan.
YES
Is it running properly?
Refer to the Fan Speed Is Out of Control
Malfunction solution.
Identify the cause and resolve.
NO
Check the heat exchanger.
YES
Is it dirty? Clean the heat exchanger.YES
Replace outdoor main board.
NO
Is the problem resolved?
Check whether the refrigerant
system is functioning properly.
NO