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INDOOR UNIT CONTROL CIRCUIT (Continued)
8
Item
Freezing
prevention control
(low-temp.
release)
Overview of specifications
(1) Performs the following operation control in the COOL or DRY
mode according to the Tc (or Tcj) sensor detect temperature.
When zone J in the figure below is detected for 6 minutes, the
specified operating frequency is decreased from the actual
operating frequency, and the specified operating frequency is
changed every 30 seconds in zone J.
Timer count stops and is maintained in zone K.
Timer count is cleared to restore normal operation when zone I is
detected.
If the specified operating frequency becomes SO due to
continuation of zone J, return temperature A is raised from 5 to
12 °C, and operation with L fan speed continues until zone I is
detected.
If 4-way valve cannot be switched during heating and the following
conditions become true, freezing prevention control is performed.
(However, zone J entering control temperature is changed from 2
to -5 °C.)
[Conditions]
The following A or B becomes true after 5 minutes pass from
operation start.
A Tcn
=
<
Tc(n–1)–5
B Tcn<Tc(n–1)–1 and Tcn
=
<
Ta<5°C
Remarks
Tcj : Indoor unit heat
exchange sensor
temp.
I5
2
Tc(˚C)
J
K
A
Tcn :
Tc after 5 minutes
from operation start
Tc (n-1):
Tc at operation start
9
(1) Performs the following operation control in the HEAT mode
according to the Tc (or Tcj) sensor detect temperature.
•
When zone M is detected, the specified operating frequency is
decreased from the actual operating frequency, and the specified
operating frequency is changed every 30 seconds in zone M.
• The specified operating frequency is maintained in zone N.
• When zone L is detected, the specified operating frequency is
returned by approx. 6 Hz every 60 seconds.
Factory setting
Note) At the beginning of operation or when Tc (or Tcj) lowers below
30 °C after operation start, values (54) and (52) in the table are
used as control temperature.
High-temp. release
control
A
B
M
N
L
Tc
Tcj
(˚C)
Control temp. (°C)
AB
56 (54) 52 (52)
This control is disabled for
twin follower indoor units.
10 Runs indoor unit fan in L (low) mode for about 30 seconds after HEAT
operation stops to remove residual heat.
Residual heat
removal
Even when the thermo is
set to OFF, the control is
implemented in the same
way.
– 21 –
NO.