13-5
TROUBLESHOOTING
SM YBD018 1-A.1 GB
No.
Fault
Probable Cause
Corrective Action
4
DC under/over Voltage
Electronics HW problem
Check outdoor unit power
supply voltage
5
AC under Voltage
Check outdoor unit power
supply voltage
6
Indoor / Outdoor unit
Communication mismatch
Indoor and Outdoor
controllers are with
different versions
Replace Indoor controller
7
No Communication
Communication or grounding
wiring is not good.
Check Indoor to Outdoor
wiring and grounding
8
Compressor Lock
Switch unit to STBY and
restart
9
Bad Communication
Communication quality is low
reliability
Check Indoor to Outdoor
wiring and grounding
13.1.4
Judgement by MegaTool
MegaTool is a special tool to monitor the system states.
Using MegaTool requires:
A computer with RS232C port.
A connection wire for MegaTool.
A special MegaTool software.
Use MegaTool according to following procedure:
Setup MegaTool software: copy the software to the computer.
Connect RS232C port in computer with MegaTool port in Indoor/Outdoor unit
controller by the connection wire.
Run the software and choose the COM port, you can monitor the A/C system state in
monitor tab.
13.2
Simple procedures for checking the Main Parts
13.2.1
Checking Mains Voltage.
Confirm that the Mains voltage is between 198 and 264 VAC. If Mains voltage is out of this
range, abnormal operation of the system is
expected.
If in range check the Power (Circuit)
Breaker and look for broken or loosed cable lugs or wiring mistake(s).
13.2.2
Checking Power Input.
If Indoor unit power LED is unlighted, power down the system and check the fuse of the Indoor
unit. If the fuse is OK replace the Indoor unit controller. If the fuse has blown, replace the fuse
and power up again.
Checking Power Input procedure for the Outdoor unit is the same as with the Indoor unit.
13.2.3
Checking the Outdoor Fan Motor.
Enter Test Mode (where the OFAN speed is high)
check the voltage between two pins( Hi and N ) of connector Controller OFAN, normal voltage
is 220VAC.
13.2.4
Checking the Compressor.
The compressor is brushless permanence magnetic DC motor. Three coil resistance is
same. Check the resistance between three poles. The normal value should be below 0.7
ohm. Pay attention U,V, W are respective to connect to RED,BROWN,BLACK wires.
