IVT 09LR-N, Service Manual

Page: 23 / 64

12LRN
3 – 1
12LRN
Service Manual
CHAPTER 3.
FUNCTION AND OPERATION OF PROTECTIVE PROCEDURES
[1] PROTECTION DEVICE FUNCTIONS AND OPERATIONS
Function Operation Self-diagnosis result
display
Description Detection period Reset condition Indoor
unit error
display
Indoor
unit
Outdoor
unit
1 Indoor unit fan lock Operation stops if there is no input
of rotation pulse signal from indoor
unit fan motor for 1 minute. When indoor unit fan is
in operation Operation OFF or ON ✩ 2 Yes None
Indoor unit fan rota-
tion speed error Operation stops if rotation pulse
signal from indoor unit fan indicates
abnormally low speed (about 300
rpm or slower). When indoor unit fan is
in operation Operation OFF or ON
✩
2 Yes None
2 Indoor unit freeze
prevention Compressor stops if temperature
remains below 0

C for 4 minutes.
When in cooling or
dehumidifying opera-
tion Automatic reset when
heat exchanger tem-
perature rises above
freeze prevention tem-
perature (2

C or
higher)
— None None
3 2-way valve freeze
prevention Compressor stops if temperature of
outdoor unit 2-way valve remains
below 0

C for 10 continuous min-
utes during cooling or dehumidify-
ing operation.
When in cooling or
dehumidifying opera-
tion Automatic reset when
temperature of 2-way
valve rises above
10

C.
None Yes Yes
4 Indoor unit heat
exchanger overheat
shutdown Operating frequency lowers if
indoor unit heat exchanger temper-
ature exceeds overheat tempera-
ture during heating operation.
Compressor stops if indoor unit
heat exchanger temperature
exceeds overheat temperature for
60 seconds at minimum frequency.
Overheat temperature setting value
indoor unit heat exchanger ther-
mistor temperature: about 45 to
54

C
When in heating opera-
tion Automatic reset after
safety period (180 sec). None Yes Yes
5 Outdoor unit heat
exchanger overheat
shutdown Operation frequency lowers if out-
door unit heat exchanger tempera-
ture 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.
When in cooling or
dehumidifying opera-
tion Automatic reset after
safety period (180 sec). None Yes Yes
6 Compressor dis-
charge overheat shut-
down Operating frequency lowers if tem-
perature of compressor chamber
thermistor (TH1) falls below about
110

C.
Compressor stops if temperature of
compressor chamber thermistor
(TH1) remains at about 110

C (for
120 seconds in cooling operation,
or 60 seconds in heating operation)
at minimum frequency.
When compressor is in
operation Automatic reset after
safety period (180 sec). None Yes Yes
7 Dehumidifying opera-
tion temporary stop Compressor stops if outside air
temperature thermistor is lower
than about 16

C during dehumidify-
ing operation.
When in dehumidifying
operation Automatic reset when
outside air tempera-
ture rises above 16

C.
None Yes Yes
8 DC overcurrent error Compressor stops if DC current of
about 25 A or higher flows in IPM.
When compressor is in
operation Operation OFF or ON Yes ✩ 1 Yes Yes
9 AC overcurrent error Operating frequency lowers if out-
door AC current exceeds peak con-
trol current value. outdoor stops if
compressor AC current exceeds
peak control current value at mini-
mum frequency.
When compressor is in
operation Operation OFF or ON Yes
✩
1 Yes Yes