Premisys MP Series - Troubleshooting - Split DX Refrigeration Circuit; Thermistor Resistance Checks; Linear Expansion Valve Resistance; Solenoid Valve Coil Resistance

35
Packaged and Split Rooftop Ventilator
Part Name Checking Points
Liquid pipe thermistor
(TH22)
Gas pipe thermistor
(TH23)
Reheat pipe thermistor
(TH25)
Disconnect the connector then measure the resistance between terminals with a tester.
(Surrounding temperature 10ºC~30ºC [50ºF~86ºF].
Normal Abnormal
4.3kΩ~9.6kΩ Open or short
<Thermistor characteristic graph>
Liquid thermistor (TH22)
Gas pipe thermistor (TH23)
Reheat pipe thermistor (TH25)
Thermistor R
10
= 15kΩ ± 3%
Fixed number of B = 3460kΩ ± 2%
Rt = 15exp {3465 (
1
⁄273+t -
1
⁄273)}
0ºC 32ºF 15kΩ
10ºC 50ºF 9.7kΩ
20ºC 68ºF 6.4kΩ
25ºC 77ºF 5.3kΩ
30ºC 86ºF 4.3kΩ
40ºC 104ºF 3.1kΩ
Linear Expansion Valve
1
2
3
4
5
6
LEV
White
Yellow
Orange
Blue
Red
Brown
CN60, CNLEV2
Disconnect the connector then measure the resistance between terminals with a tester.
Normal Abnormal
1-5
White-Red
2-6
Yellow-Brown
3-5
Orange-Red
4-6
Blue-Brown
Open or short
200 kΩ ± 10%
Solenoid valve coil
SV10, SV11
Measure the resistance between the terminals with a tester.
(Surrounding temperature 20ºC [68ºF]
Normal Abnormal
1183Ω ± 100% Open or short
(Refer to the <Thermistor
characteristic graph>)
0
10
20
30
40
50
-20-10 01020304050
Temperature
(˚C)
- 41432506886 104 122
[˚F]
Resistance (KΩ)
Troubleshooting – Split DX Refrigeration Circuit
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