H6; How To Check Whether The Transformer Of Idu Is Disabled; H7: Quantity Of Indoor Units Decrease Error - Midea VRF V4 Plus I Series Manual

MCAC-VTSM-2014-04
5.6 H6: Quantity of indoor units decrease error (Only display on master unit, all the ODU in standby)
"H7" error will display when the quantity of indoor units decrease above 3 minutes.
H7: Quantity of indoor units
decrease error
Communication terminals P Q E
are loose
Some IDU are assigned the
same address
Some IDU are power off
Transformer of IDU is disabled
IDU are not unified power supply*
485 communication IC is disabled
IDU Main
disabled
Note:

1. How to check whether the transformer of IDU is disabled

The voltage input for IDU transformer is 220V, the voltage output of is AC9V (yellow-yellow) and AC13.5V (brown-brown)
2. How to check whether the 485 communication IC is disabled
The normal voltage between "P" and "GND" is DC2.5~2.7V, between "Q" and "GND" is DC2.5~2.7V. If the voltage is out of the
normal range, the 485 communication IC is disabled.
*Indoor units should be unified power supply, which can prevent compressor from liquid hammer caused by dropped indoor
units with EXV unclosed.
Troubleshooting
No
No
No
①
No
No
No
board is
Yes
Fasten the communication
terminals
Yes
Set the IDU addresses differently
Yes
Power on all IDU
Yes
Replace the transformer
Yes
Insure all the IDU be unified
power supply
②
Replace the IDU PCB
①
②
P Q E terminals
R410A DC Inverter V4 Plus 50Hz
101