Carrier 38QUS012D8S Service Manual page 139

2.4.4.18. P6/J6 Malfunction
Malfunction conditions
Possible causes
J6 displayed
J6 displayed
Low pressure protection
Low pressure protection
Are the low pressure
Are the low pressure
protector and main control
protector and main control
board wired properly?
board wired properly?
Yes
Is the low
Is the low
pressure protector
pressure protector
broken?
broken?
Method: Disconnect the plug.
Method: Disconnect the plug.
Measure the resistance of the
Measure the resistance of the
low pressure protector. If the
low pressure protector. If the
protector is normal the value is
protector is normal the value is
o. Does a problem still exist?
o. Does a problem still exist?
Yes
Is the outdoor ambient
Is the outdoor ambient
temperature too low?
temperature too low?
No
Is the valve core of the
Is the valve core of the
high pressure valve fully
high pressure valve fully
opened?
opened?
Yes
Is the indoor fan running
Is the indoor fan running
properly in cooling mode?
properly in cooling mode?
Yes
Replace outdoor main board.
Replace outdoor main board.
Does a problem still exist?
Does a problem still exist?
No
When the lvel of refrigerant is not
When the lvel of refrigerant is not
sufficient, doe the system function
sufficient, doe the system function
properly after more refrigerant is
properly after more refrigerant is
added?
added?
No
Check whether the refrigerant
Check whether the refrigerant
system is functioning properly.
system is functioning properly.
Electrical Control System
If the sampling voltage is not 5V, the LED displays a failure
code.
● Wiring mistake
Faulty over load protector
●
● System blockages
●
Faulty outdoor PCB
Reconnect the low pressure
Reconnect the low pressure
protector and main control
No
protector and main control
board
board
Replace low pressure protector
No
Replace low pressure protector
Yes Stop the unit
Stop the unit
Open the valve core of the
Open the valve core of the
No
high pressure valve
high pressure valve
Refer to the solution to the malfunction
Refer to the solution to the malfunction
of fan speed being out of control. Find
of fan speed being out of control. Find
No
the cause and resolve the problem.
the cause and resolve the problem.
Troubleshooting
137