Hitachi RAS-3HVRNS - Alarm Code 31

12.5 Alarm code "31"
Question and answer for the field work
Example 4: Alarm code "31"
Phenomenon Alarm code "31" sometimes occurred and the system stopped.
Cause
The combination of the indoor units and the outdoor unit was the following.
ON
OFF
ON ON ON ON
Power
Source
This system was used in a tenant building. One of tenant's customers turned off the main switch for the indoor unit while
other indoor units are running. This results in a different setting of the total indoor unit capacity in the same refrigerant cycle.
Countermeasure
All the main switches for the indoor units were always ON.
12 Maintenace notes
462
SMGB0060 rev. 1- 12/2010