8.4 SPECIAL DETAILED DIAGNOSIS
8.4.1 DETECT THE MAIN PCB & DISPLAY/CONTROL PCB
1. The control system including the MAIN PCB and DISPLAY/CONTROL PCB operates when
the unit is powered. If not, the unit is either POWER OFF or Switch OFF. If neither operates,
check the control system including the main PCB and Display/Control PCB and connecting
wirings.
2. The first step is to check and see if there is any component failed in the PCBs by using your
common sense.
3. To Check The Main PCB,
Disconnect the unit from the power source.
Dismantle the electrical box in the compressor room and take out the main PCB.
Disconnect the lead connectors of all fan motors and compressor from the cable.
Carefully place the main PCB so that it is insulated from any other part.
Connect the unit to the power source.
Check the output voltage of all fan motors and compressor connectors on the main PCB.
The correct output voltage of all fan motors connectors should be 12V DC. The correct
output voltage of compressor connector should be same as the power source. If not, the
main PCB must be replaced.
4. Replace the Display/Control PCB for the below symptoms after you confirm that the Main
PCB is normal.
No LED temperature display or indicator illuminated in the control panel.
Some LEDs do not light.
No response when touching the control marks. (For this kind of symptom, double check
to see if there any response after disconnect the power before replacing the
Display/Control PCB.)
The unit does not run correctly in the TEST MODE. In order to run in TEST MODE, Touch
and hold the “
LIGHT
” and “
UP
” marks at the same time for 5 seconds.
5. If you can’t find the failure from the existed symptoms, replace the Main PCB and
Display/Control PCB separately to see which one is failed and then replace the failed PCB.
8.4.2 DETECT THE CONDENSER FAN MOTOR (F0)
1. The condenser fan motor operates in parallel with the compressor. If the compressor runs
but the motor doesn't, the motor is either defective or disconnected. If neither operates,
check the main PCB and the cabinet wiring.
2. To Check The Condenser Fan Motor,
Disconnect the unit from the source.
Disconnect the condenser fan motor lead connector from the cable.
Connect the condenser motor to a 12V DC power source. If the motor fails to operate, it is
defective and must be replaced.
8.4.3 DETECT THE EVAPOARTOR FAN MOTOR (F1C/F1H)
1. The evaporator fan motor operates when the compressor operates and at the rest time it
cycles ON and OFF to circulate the interior air. If the compressor runs but the motor doesn't,
