Mitsubishi Electric CITY MULTI PFFY-W20VCM-A, Technical & Service Manual, Page: 17 / 38

[
VII
Troubleshooting ]
- 12 -
HWE18170 GB
VII Troubleshooting [1] Troubleshooting
1. Check methods
1. Component and check points
(1) Thermistor
 Room temperature thermistor (TH21)
 Water inlet thermistor (TH22)
 Water outlet thermistor (TH23)
Disconnect the connector and measure the resistance between terminals with a tester.
(Ambient temperature 10°C - 30°C)
1) Thermistor characteristic graph
(2) Fan motor (CNMF1)
Refer to the page on "DC fan motor (fan motor/indoor control board)."
(3) Flow control valve
Disconnect the connector, and measure the resistance between terminals with a tester.
Refer to the next page for details.
Normal Abnormal
4.3kΩ - 9.6kΩ Open or short
(Refer to the thermistor characteristic graph below.)
Low-temperature thermistor
 Room temperature thermistor (TH21)
 Water inlet thermistor (TH22)
 Water outlet thermistor (TH23)
 Thermistor R
0
= 15 kΩ 3%
 Multiplier of B = 3480 kΩ 2%
0°C 15kΩ
10°C 9.6kΩ
20°C 6.3kΩ
25°C 5.2kΩ
30°C 4.3kΩ
40°C 3.0kΩ
(A) Temperature (°C)
(B) Resistance (kΩ)
Normal Abnormal
1-5 2-5 3-5 4-5 Open or short
Purple-Brown Orange-Brown Blue-Brown Green-Brown
55Ω / PHASE
(A) Yellow (E) Green
(B) White (F) Blue
(C) Black (G) Orange
(D) Brown (H) Purple
Rt = 15 exp { 3480( ) }
1
273+t
1
273
0
10
20
30
40
50
-20 -10 0 10 20 30 40 50
(A)
(B)
1
2
3
4
5
6
7
8
FCV
M
(A)
(B)
(C)
(D)
(E)
(F)
(G)
(H)
CN8A
HWE18170.book 12 ページ ２０１９年５月８日 水曜日 午前１０時３２分