Air Conditioner Operation In Thermistor Error - IVT AE-X12GR-N Service Manual

Function
25 Compressor star- Compressor stops if compressor
tup error fails to start up.
26 Compressor rota- Compressor stops if there is no
tion error (at 120° input of position detection signal
energizing) from compressor or input is
abnormal.
27 Outdoor unit DC fan Operation stops if there is no
error input of rotation pulse signal from
outdoor unit fan motor for 30 sec-
onds.
28 PAM overvoltage Compressor stops if DC voltage is
error 350 V or higher.
29 PAM clock error When power source frequency
cannot be determined (at startup),
or when power source clock can-
not be detected for 1 continuous
second (at startup).
30 IPM pin level error When Outdoor unit starts to run,
MCU checks 6 control pin levels
of IPM. If MCU detects some pin
levels isn't different from another
pin level. MCU doesn't run Com-
pressor.
✩1—The outdoor unit restarts four times before the indoor unit error is displayed (complete shutdown).
✩2—A single error judgment results in the display of the indoor unit error (complete shutdown).
✩3—The outdoor unit restarts eight times before the indoor unit error is displayed (complete shutdown).

[2] AIR CONDITIONER OPERATION IN THERMISTOR ERROR

1. Indoor unit
Item Mode
Room tempera- Auto
ture thermistor
(TH1)
Cooling
Dehumidifying
Heating
Heat exchanger Cooling
thermistor (TH2) Dehumidifying
Heating
Description Detection period
At compressor star-
tup
Compressor operat-
ing at 120° energizing
When outdoor unit
fan is in operation
When in operation
At compressor star-
tup, when in opera-
tion
At compressor star-
tup
Control opera- When resistance is
tion low (temperature
judged higher than
actual)
Operation mode Cooling mode is acti-
judgment vated even if room
temperature is low.
Frequency control Room becomes too
cold.
Room tempera- Normal operation.
ture memory
Frequency control
Frequency control Room does not
become warm.
Freeze preven- Indoor unit evapora-
tion tor may freeze.
Cold air preven- Cold air prevention
tion deactivates too soon
and cold air dis-
charges.
Operation
Reset condition
Operation OFF or ON Yes ✩3
Operation OFF or ON Yes ✩3
Operation OFF or ON Yes ✩1
Operation OFF or ON Yes ✩1
Compressor contin-
ues operation with-
out stopping.
Operation OFF or ON Yes ✩1
Short-circuit
Cooling mode is acti-
vated in most cases.
Air conditioner oper-
ates in full power
even when set tem-
perature is reached.
Room temperature is
stored in memory as
31.0°C, and com-
pressor does not
stop.
Hot keep status
results immediately
after operation starts.
Frequency does not
increase above 30 Hz
(40 Hz).
Indoor unit evapora-
tor may freeze.
Compressor operates
at low speed or stops,
and frequency does
not increase.
3 – 3
AEX12GRN
Self-diagnosis
result display
Indoor Indoor Outdoor
unit error unit
display
Yes Yes
Yes Yes
Yes Yes
Yes Yes
None Yes Yes
Yes Yes
When resistance Open-circuit
is high (tempera-
ture judged lower
than actual)
Heating mode is Heating mode is
activated even if always activated.
room temperature is
high.
Room does not Compressor does
become cool. not operate.
Normal operation. Room tempera-
ture is stored in
memory as
18.5°C, and com-
pressor does not
operate.
Room becomes too Air conditioner
warm. operates in full
power even when
set temperature is
reached.
Compressor stops Compressor does
occasionally. not operate.
Cold air prevention Cold air preven-
deactivates too tion does not
slow. deactivate, and
indoor unit fan
does not rotate.
unit