CHAPTER 3.
AEX12GRN
FUNCTION AND OPERATION OF PROTECTIVE PROCEDURES
[1] PROTECTION DEVICE FUNCTIONS AND OPERATIONS
Function
1
Indoor unit fan lock
Operation stops if there is no
input of rotation pulse signal from
indoor unit fan motor for 1 minute.
Indoor unit fan rota-
Operation stops if rotation pulse
tion speed error
signal from indoor unit fan indi-
cates abnormally low speed
(about 300 rpm or slower).
2
Indoor unit freeze
Compressor stops if temperature
prevention
remains below 0°C for 4 minutes.
3
2-way valve freeze
Compressor stops if temperature
prevention
of outdoor unit 2-way valve
remains below 0°C for 10 continu-
ous minutes during cooling or
dehumidifying operation.
4
Indoor unit heat
Operating frequency lowers if
exchanger over-
indoor unit heat exchanger tem-
heat shutdown
perature exceeds overheat tem-
perature during heating
operation.
Compressor stops if indoor unit
heat exchanger temperature
exceeds overheat temperature for
60 seconds at minimum fre-
quency.
Overheat temperature setting
value indoor unit heat exchanger
thermistor temperature: about 45
to 54°C
5
Outdoor unit heat
Operation frequency lowers if out-
exchanger over-
door unit heat exchanger temper-
heat shutdown
ature exceeds about 55°C during
cooling operation.
Compressor stops if outdoor unit
heat exchanger temperature
exceeds about 55°C for 120 sec-
onds at minimum frequency.
6
Compressor dis-
Operating frequency lowers if
charge overheat
temperature of compressor
shutdown
chamber thermistor (TH1) falls
below about 110°C.
Compressor stops if temperature
of compressor chamber ther-
mistor (TH1) remains at about
110°C (for 120 seconds in cooling
operation, or 60 seconds in heat-
ing operation) at minimum fre-
quency.
7
Dehumidifying oper-
Compressor stops if outside air
ation temporary
temperature thermistor is lower
stop
than about 16°C during dehumidi-
fying operation.
8
DC overcurrent
Compressor stops if electric cur-
error
rent of about 25 A or higher flows
in IPM.
Operation
Description
Detection period
When indoor unit fan
is in operation
When indoor unit fan
is in operation
When in cooling or
dehumidifying opera-
tion
When in cooling or
dehumidifying opera-
tion
When in heating
operation
When in cooling or
dehumidifying opera-
tion
When compressor is
in operation
When in dehumidify-
ing operation
When compressor is
in operation
Service Manual
Reset condition
Operation OFF or ON ✩2
Operation OFF or ON ✩2
Automatic reset when
heat exchanger tem-
perature rises above
freeze prevention
temperature (2°C or
higher)
Automatic reset when
temperature of 2-way
valve rises above
10°C.
Automatic reset after
safety period (180
sec).
Automatic reset after
safety period (180
sec).
Automatic reset after
safety period (180
sec).
Automatic reset when
outside air tempera-
ture rises above
16°C.
Operation OFF or ON Yes ✩1
3 – 1
AEX12GRN
Self-diagnosis
result display
Indoor
Indoor
Outdoor
unit error
unit
unit
display
Yes
None
Yes
None
—
None
None
None
Yes
Yes
None
Yes
Yes
None
Yes
Yes
None
Yes
Yes
None
Yes
Yes
Yes
Yes