V6-i VRF 50/60Hz 
    75 
Part 
6 - Diagnosis and Troubleshooting
 
 Procedure 2.3.5
 
Communication wires P Q E have short 
circuited or disconnected
1
 
Reconnect the communication wires 
Communication wires P Q E are not 
connected in a daisy chain 
Connect the communication wires in a 
daisy chain 
IDU power supply is abnormal 
Ensure normal power supply 
Wires between outdoor main PCB and 
electric control box communication 
terminals block are loose 
Ensure the wires are connected properly 
Interference from high voltage (220V or 
higher) wires 
Ensure the communication wires and 
high voltage wires are separated 
Communication wires are close to a 
source of electromagnetic radiation such 
as transformer or strong fluorescent lamp 
Remove the source of interference, or 
add additional shielding to the 
communication wires 
The length of communication wire is over 
1200m 
Reduce the wire length to less than 
1200m or strengthen the signal 
Replacing outdoor main PCB resolves the 
error 
Replace electric control box 
communication terminals block 
 
Notes:   
1.  Measure the resistance among P, Q and E. The normal resistance between P and Q is 120Ω, between P and E is infinite, between Q and E is infinite.