Hitachi Set Free mini-HNRQ1 Series, Service Manual

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3.3 Checking Method of Electronic Expansion Valve
For Indoor Unit For Outdoor Unit
Locked with Fully Closed
Check for the liquid pipe temperature during the
heating operation.
It is abnormal if the temperature does not
increase.
It is abnormal if the liquid pipe pressure does not
increase during the cooling operation.
Locked with slightly opened
It is abnormal under under the following
conditions;The temperature of freeze protection
thermistor becomes lower than the inlet air
temperature when the unit under checking is
stopped and other units are under the cooling
operation
It is abnormal if the liquid pipe pressure does
not increase and the outlet temperature of the
expansion valve decreases after the cooling
operation is started.
Locked with Fully Opened
It is abnormal under under the following
conditions;After heating operation for more
than 30 min.,the discharge gas temperature
of compressor is not +10°C higher than the
condensing temperature and there is no other
faults such as excessive charge of refrigerant,etc.
TROUBLESHOOTING