Automatic Operation; Protective Control Function - Mitsubishi Heavy Industries SRK20HC-S Technical Manual

4.9 Automatic operation

(1) Determination of operation mode
The blow operation of the indoor fan is carried out at the 1st speed for 20 seconds and the room temperature is checked to
determine the operation mode automatically. (When the unit is operated by the turn-on timer, the blow operation is not carried out.)
Room temperature
Operation mode
(2) Within 30 minutes after either auto or manual operation stops, if auto operation is started, or if you switch to auto operation during
manual operation, the system runs in the previous operation mode.
(3) The temperature is checked 1 time in 30 minutes after the start of operation, and if the judgment differs from the previous operation
mode, the operation mode changes.
(4) Setting temperature can be adjusted within the following range. There is the relationship as shown below between the signals of the
wireless remote controller and the setting temperature.
Cooling
Setting
Dehumidifying
temperature
Heating

4.10 Protective control function

(1) Frost prevention for indoor heat exchanger (During cooling or dehumidifying)
(a) Operating conditions
(i) Indoor heat exchanger temperature (detected with Th2) is lower than 2.5ºC.
(ii) 3 minutes elapsed after the start of operation.
(b) Detail of anti-frost operation
Compressor
Indoor fan
Outdoor fan
4-way valve
(c) Reset conditions: Indoor heat exchanger temperature (Th2) is higher than 8ºC.
(2) Indoor fan motor protection
When the air conditioner is operating and the indoor fan motor is turned ON, if the indoor fan motor has operated at 300 rpm or
under for more than 30 seconds, the unit enters first in the stop mode and then stops the entire system.
Timer lamp illuminates simultaneously and the operation lamp flashing 6 times at each 8-second.
(3) Dew condensation prevention control for cooling operation
This prevents dew condensation, in the indoor unit, from occurring.
(a) Operating condition: when compressor is kept ON for 30 min. after the unit starts operation.
(b) Operation content: forces the indoor fan to change from Speed 1 to Speed 2.
(c) Resetting condition: When compressor is off, or when dew condensation prevention control has been operating continu-
ously for 30 minutes.
(4) Three-minute forced operation
When the compressor begins operating the thermal operation is not effective for 3 minutes, so operation continues as is in the
operation mode. (After 3 minutes has passed the thermal operation is effective.)
However, stopping the compressor via a stop signal or protection control has priority.
Room temp.<21˚C
Heating
Signals of wireless remote controller (Display)
–6 –5 –4 –3
19 20 21 22
19 20 21 22
20 21 22 23
OFF
1st speed
OFF
Stop mode
18
- -
<
21˚C Room temp.<26˚C
=
Dry
±0
–2 –1 +1
23 24 25 26
23 24 25 26
24 25 26 27
<
26˚C Room temp.
=
Cooling
+2 +3 +4 +5
27 28 29 30
27 28 29 30
28 29 30 31
+6
31
31
32