Check; Thermistor Resistance Check - Daikin FTKM-U Series Service Manual

Check

5. Check

5.1

Thermistor Resistance Check

Check No.01 Measure the resistance of each thermistor using multimeter.
The resistance values are defined by below table.
If the measured resistance value does not match the listed value, the thermistor must be
replaced.
 Disconnect the connector of thermistor ASSY from the PCB to measure the resistance
 To check the thermistor soldered on a PCB, disconnect the PCB from other PCB/parts, and
Indoor
Unit
Outdoor
Unit
Note
When replacing the defective thermistor(s), replace the thermistor as ASSY.
90
between the pins using multimeter.
measure the resistance between the both ends of soldered thermistor.
Thermistor ASSY
Type A
Thermistor
R(25°C) = 20 k:
temperature (°C)
B = 3950 K
–20
–15
–10
–5
0
5
10
15
20
25
30
35
40
45
50
Thermistor
R1T Room temperature thermistor
R2T Indoor heat exchanger thermistor
R1T Outdoor temperature thermistor
R2T Outdoor heat exchanger thermistor
R3T Discharge pipe thermistor
Multimeter
Resistance range
Type B
R(25°C) = 10 k:
B = 3435 K
197.8 73.4
148.2 57.0
112.1 44.7
85.60 35.3
65.93 28.2
51.14 22.6
39.99 18.3
31.52 14.8
25.02 12.1
20.00 10.0
16.10 8.2
13.04 6.9
10.62 5.8
8.707 4.9
7.176 4.1
Resistance Type
SiMX042215E
Soldered thermistor
Multimeter
R(25°C) = 20 k :, B = 3950 K
(k:)
150
100
50
–15 0 15 30 45 (°C)
(k:) R(25°C) = 10 k:, B = 3435 K
50
25
0
–15 15 30 45 (°C)
0
B value
B 3435 K
A 3950 K
A 3950 K
A 3950 K
A 3950 K
Part 6 Service Diagnosis
R6000664
R(25°C)
10 kΩ
20 kΩ
20 kΩ
20 kΩ
20 kΩ