Thermistor Temperature Characteristics; Air Conditioner Operation In Thermistor Error - Sharp AY-XPC12PU Service Manual

AY-XPC12PU

[2] THERMISTOR TEMPERATURE CHARACTERISTICS.

Thermistor
Room temperature
Heat exchanger temperature
Liquid pipe temperature
100
Heat exchanger/Liquid pipe thermistor
80
TH2 (Orange), TH3 (Black)
25ºC resistance 4.431
60
40
20
0
-10 0

[3] AIR CONDITIONER OPERATION IN THERMISTOR ERROR

* These models have following thermistors.
AY-XPC07PU, AY-XPC09PU, AY-XPC12PU
The errors for the thermistors that are not mentioned above are irrelevant.
These indoor units don't have power relay.
Item Mode
Room temperature Auto
thermistor (TH1)
Cooling
Dehumidifying
Heating
Heat exchanger Cooling
thermistor (TH2) Dehumidifying
Heating
To measure the resistance, first remove
the soldering as shown at right.
Room temperature
thermistor TH1 (Yellow)
25ºC resistance 10
10 20 30 40
Temperature
INDOOR UNIT
Control operation When resistance
is low (tempera-
ture judged
higher than
Operation mode Cooling mode is
judgment activated even if
room temperature
is low.
Frequency control Room becomes too
cold.
Room temperature Normal operation.
memory
Frequency control
Frequency control Room does not
become warm.
Freeze prevention Indoor unit evapo-
ration may freeze.
Cold air prevention Cold air prevention
deactivates too
soon and cold air
discharges.
Color
Signal
Yellow
TH1
Orange
TH2
Black
TH3
CN2
1
Tester
ºC
TH1, TH2, TH3
Short-circuit
actual)
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℃, 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-
tion may freeze.
Compressor oper-
ates at low speed or
stop, and frequency
does not increase.
3 – 8
Room temperature
thermistor TH1 (CN2 3 - 4 )
Heat exchanger temperature
thermistor TH2 (CN2 1 - 2 )
Liquid pipe temperature
thermistor TH3 (CN2 5 - 6 )
6
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 not
become cool. operate.
Normal operation. Room temperature is
stored in memory as
18.5℃, and compres-
sor does not operate.
Room becomes too Air conditioner oper-
warm. ates in full power even
when set temperature
is reached.
Compressor stops Compressor does not
occasionally. operate.
Cold air prevention Cold air prevention
deactivates too does not deactivate,
slow. and indoor unit fan
does not rotate.