Carrier 38MGQ Series Service Manual page 53

P0(Temperature protection of compressor top) error diagnosis and solution.
Error Code
Malfunction decision conditions
Supposed causes
Troubleshooting
Temperature protection of compressor
Temperature protection of compressor
top
top
Check the air flow system
Check the air flow system
of indoor and outdoor units
of indoor and outdoor units
No
Power off, then restart the unit 10
Power off, then restart the unit 10
minutes later
minutes later
Yes
Check whether the
Check whether the
temperature of
temperature of
compressor top is more
compressor top is more
than 100
than 100
Yes
Check the refrigerant
Check the refrigerant
volume charge
volume charge
Yes
Refrigerant system is blocked, such
Refrigerant system is blocked, such
as capillary or welded point of pipes.
as capillary or welded point of pipes.
P0
If the sampling voltage is not 5V, the LED displays the failure.
S
Wiring mistake
S
Over load protector faulty
S
System block
S
Outdoor PCB faulty
Clear up the air inlet and outlet or the heat
Clear up the air inlet and outlet or the heat
Yes
exchanger of indoor and outdoor units.
exchanger of indoor and outdoor units.
Check wiring connection
Check wiring connection
No
of the overload protector
of the overload protector
Yes
Measure the
Measure the
between the two ports of
between the two ports of
the OLP. Is it zero?
the OLP. Is it zero?
No
Recharge the correct
Recharge the correct
refrigerant volume.
refrigerant volume.
53
No Correct the connection.
Correct the connection.
resistance
resistance
No Replace the OLP.
Replace the OLP.
Yes Replace the outdoor main PCB.
Replace the outdoor main PCB.