Midea MV5-X252W/V2GN1 Service Manual page 56

4.4.4 Procedure
Communication wires P Q E have short
circuited or disconnected
Communication wires P Q E are not
connected in a daisy chain
IDU power supply is abnormal
Wires between outdoor main PCB and
electric control box communication
terminals block are loose
Interference from high voltage (220V or
Communication wires are close to a
source of electromagnetic radiation such
as transformer or strong fluorescent lamp
The length of communication wire is over
Replacing outdoor main PCB resolves the
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. Refer
to Figures 5-1.2 and 5-1.4 in Part 5, 1 "Outdoor Unit Electric Control Box Layout" and to the V5 X Engineering Data Book, Part 3, 9.3 "Communication
Wiring".
2. Refer to the V5 X Engineering Data Book, Part 3, 9.3 "Communication Wiring".
3. Refer to Figures 5-1.2 and 5-1.4 in Part 5, 1 "Outdoor Unit Electric Control Box Layout" and to the V5 X Engineering Data Book, Part 2, 5 "Wiring Diagrams".
4. Refer to the V5 X Engineering Data Book, Part 3, 9.1 "General" for required separation distances between communication wiring and power wiring.
5. Refer to Figures 5-1.2 and 5-1.4 in Part 5, 1 "Outdoor Unit Electric Control Box Layout".
201608
E2
1
No
2
No
No
3
No
4
higher) wires
No
No
1200m
No
error
No
5
Yes
Reconnect the communication wires
Connect the communication wires in a
Yes
daisy chain
Yes
Ensure normal power supply
Yes
Ensure the wires are connected properly
Ensure the communication wires and
Yes
high voltage wires are separated
Remove the source of interference, or
Yes
add additional shielding to the
communication wires
Reduce the wire length to less than
Yes
1200m or strengthen the signal
V5 X VRF 50/60Hz
55