DM14-01.01.18en
MIV V5 Heat Recovery DC Inverter R410A
169
Troubleshooting
4.10 H7: Quantity of indoor units decrease error
The error only display on master unit, all the ODU will be standby. It will display when the quantity of indoor
units decrease above 3 minutes.
Note:
1. How to check whether the transformer of IDU is disabled
①
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
②
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.
H7: Quantity of indoor units
decrease error
Communication terminals P Q E
are loose
Fasten the communication
terminals
Yes
Transformer of IDU is disabled
①
Replace the transformer
IDU are not unified power supply
*
Insure all the IDU be unified
power supply
485 communication IC is disabled
②
IDU PCB is disabled
Replace the IDU PCB
No
No
No
No
Yes
Yes
Some IDU are assigned the
same address
Some IDU are power off
Set the IDU addresses differently
Power on all IDU
No
No
Yes
Yes
P Q E
terminals
