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4. HOW TO CHECK THE PARTS
Room temperature
thermistor (RT1)
Pipe temperature
thermistor (RT2)
Fan motor (MF)
Disconnect the connector, then measure the resistance using a tester.
(Surrounding temperature 50°F to 86°F)
Measure the resistance between the terminals using a tester.
(Refer to the thermistor)
Normal
4.3k' to 9.6k'
Abnormal
Open or short
Motor terminal
or
Relay connector
Normal
PKH
18,24FL
Abnormal
Red-White
99.5'i10%
Open or short
White-Black
103.5'i10%
1
1
3
3
5
5
Red
White
Black
Relay connector
Protector
Parts name Check points
0
10
20
30
40
50
-4 14 32 50 68 86 104 122
< Thermistor for lower temperature >
Temperature (°F)
Resistance (K")
<Thermistor Characteristic graph>
Room temperature thermistor(RT1)
Pipe temperature thermistor(RT2)
Thermistor R0=15k' ±3%
Fixed number of B=3480k' ±2%
Rt=15exp { 3480( ) }
32°F 15k'
50°F 9.6k'
68°F 6.3k'
77°F 5.4k'
86°F 4.3k'
104°F 3.0k'
Thermistor for
lower temperature
1
273+t
1
273
30,36FL
62.6'i10%
74.0'i10%
Vane motor (MV)
Measure the resistance between the terminals using a tester.
(Surrounding temperature 68°F to 86°F)
Normal
186 to 214'
Abnormal
Open or short
3 6 1
4
5
2
M
Pink
Connector
Red
Orange
Blue
Brown
Yellow
Brown-Yellow
Brown-Blue
Red-Orange
Red-Pink
Opening and closing temperature of protector.
Open: 266i41°F (Fan motor OFF)
Close: 176i68°F (Fan motor ON)
OC276-A-2.qxp 03.11.25 9:06 AM Page 44
