Standard Control Functions; Freezing Protection During Cooling Process Or Dry Operation - Hitachi RAS-(3-6)HVNC1(E) Service Manual

5 Control System
5.5 Standard control functions
5.5.1 Freezing protection during cooling process or dry operation
Cooling or dry
operation
IU: Indoor unit
155
SMGB0087 rev.0 - 12/2013
Power supply
Is
compres-
No
sor operated for
more than 30min. *1) ?
*1) : The check interval differs
depending on the conditions
Yes
Gas
or liquid
pipe surface tempera-
ture on heat ex-
changer
Lower than 0ºC
Is
it
continuous for
more than 3 min.?
Yes
MIF operation at set fan speed
(in case of dry operation.
MIF operation: OFF for 6 min.)
For individual
operation
IU electronic expansion valve:
completely closed
Is
it conti-
nuous for more than
3 min.? (6 min in case of
dry operation)
Yes
a
Gas or
liquid pipe surface
temp of indoor heat
exchanger
Higher than 14ºC
15
Yes
min
progress
No
Either
No
of pipe surface
temp *2) > 2ºC
*2) : Pipe surface temperature
Yes
NOT adpopted at
Cooling or dry
operation
Higher than 0ºC
No
For simultaneous or
single operation
Inverter frequency = 0 Hz
No
Lower than 14ºC
a
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