– 30 –
INDOOR UNIT CONTROL CIRCUIT (CONTINUED)
NO.
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 (1) or (2) becomes true after 5 minutes
pass from operation start.
(1) Tcn
≤
Tc (n-1) –5
(2) Tcn < Tc (n-1) –1 and Tcn
≤
Ta < 5°C
Remarks
Tcj:
Indoor unit heat exchange
sensor temp.
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.
5
2
A
J
K
I
Tc(˚C)
A
B
L
N
M
Tc, Tcj
(˚C)
Control temp. (°C)
A
B
56 (54)
52 (52)
(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
Runs indoor unit fan in L (low) mode for about 30 seconds
after HEAT operation stops to remove residual heat.
High-temp. release control
Residual heat removal
9
10
Tcn:
Tc after 5 minutes from
operation start
Tc (n-1):
Tc at operation start
This control is disabled for
twin follower indoor units.
Even when the thermo is set
to OFF, the control is
implemented in the same
way.
