Mitsubishi Heavy Industries SRK20ZJX-S Service Manual page 24

(m) Operation check/drain pump test run operation mode
1) If the power is turned on by the dip switch (SW7-1) on the indoor PCB when electric power source is supplied, it enters the
mode of operation check/drain pump test run. It is ineffective (prohibited) to change the switch after turning power on.
2) When the communication with the remote controller has been established within 60 seconds after turning power on by the
dip switch (SW7-1) ON, it enters the operation check mode. Unless the remote controller communication is established, it
enters the drain pump test run mode.
Note (1) To select the drain pump test run mode, disconnect the remote controller connector (CNB) on the indoor PCB to shut down the remote controller
communication.
3) Operation check mode
There is no communication with the outdoor unit but it allows performing operation in respective modes by operating the
remote controller.
4) Drain pump test run mode
As the drain pump test run is established, the drain pump only operates and during the operation protective functions by
the microcomputer of indoor unit become ineffective.
(n) Cooling, dehumidifying frost protection
1) To prevent frosting during cooling mode or dehumidifying mode operation, the of compressor speed is reduced if
the indoor heat exchanger temperature (detected with Th
compressor operation. If the indoor unit heat exchanger temperature is 1.0 °C or lower after 20 seconds, the compressor
speed is reduced further. If it becomes 2.5 °C or higher, the control terminates. When the indoor heat exchanger
temperature has become as show below after reducing the compressor speed, it is switched to the fan operation. For the
selection of indoor fan speed, refer to item 2).
2) Selection of indoor fan speed
If it enters the frost prevention control during cooling operation (excluding dehumidifying), the indoor unit fan speed is
switched.
a) When the indoor return air detection temperature (detected with Th
exchanger temperature (detected with Th
of indoor unit fan speed is increased by 20rpm.
b) If the phenomenon of i) above is detected again after the acceleration of indoor unit fan, indoor unit fan speed
is increased further by 20rpm.
Note (1) Indoor unit fan speed can be increased by up to 2 taps.
• Compressor frequency drop start temperature
Item
Temperature - Low (Factory default)
Temperature - High
Note (1) Frost prevention temperature setting can be selected with the indoor unit function setting of the wired remote controller.
(o) Heating overload protection
1) If the indoor heat exchanger temperature (detected with Th
the compressor stops. When the compressor is restarted after a 3-minute delay, if a temperature at 63°C or higher is
detected for 2 seconds continuously within 60 minutes after initial detection and if this is detected 5 times consecutively,
the compressor stops with the anomalous stop (E8). Anomalous stop occurs also when the indoor heat exchanger
temperature at 63°C or higher is detected for 6 minutes continuously.
2) Indoor unit fan speed selection
If, after second detection of heating overload protection up to fourth, the indoor fan is set at Me and Lo taps when the
compressor is turned ON, the indoor fan speed is increased by 1 tap.
(p) Anomalous fan motor
After starting the fan motor, if the fan motor speed is 200rpm or less is detected for 30 seconds continuously and 4 times within
60 minutes, then fan motor stops with the anomalous stop (E16).
-R) drops to 1.0 °C or lower at 4 minutes after the start of
I
Cooling operation
Fan operation
1.0 10
Indoor heat exchanger temperature (°C)
-R) detects the compressor frequency drop start temperature A°C+1°C,
I
Symbol
A
1.0
2.5
-R) at 63°C or higher is detected for 2 seconds continuously,
I
Compressor OFF
Compressor ON
56
63
Indoor heat exchanger temperature (°C)
23
- -
'10 • SCM-SM-094
Symbol
Model
SRC40~60
FDC100~140
-A) is 23°C or higher and the indoor heat
I
A B C
4 1 1.0
4 1 1.0