Troubleshooting; Check Methods - Mitsubishi Electric CITY MULTI PEFY-AF1200CFM-E Technical & Service Manual

[ VIII Troubleshooting ]

[2] Troubleshooting

1. Check methods

1. Component and check points
(1) Thermistor
Supply air temperature thermistor (TH21-1, TH21-2)
Liquid pipe thermistor (TH22-1, TH22-2)
Gas pipe thermistor (TH23-1, TH23-2)
Inlet air temperature thermistor (TH24)
Disconnect the connector and measure the resistance between terminals with a tester.
(Ambient temperature 10°C - 30°C[50°F-86°F])
Normal
4.3k - 9.6k
(Refer to the thermistor characteristic graph below.)
1) Thermistor characteristic graph
Low-temperature thermistor
Room temperature thermistor (TH21)
Liquid pipe thermistor (TH22)
Gas pipe thermistor (TH23)
Drain sensor (DS)
Thermistor R = 15 k
0
Multiplier of B = 3480 2%
Rt = 15 exp { 3480(
273+t
0°C 32°F 15k
10°C 50°F 9.6k
20°C 68°F 6.3k
25°C 77°F 5.2k
30°C 86°F 4.3k
40°C 104°F 3.0k
(A) Temperature
(B) Resistance
(2) Humidity sensor
Check the voltage across pins No.1 and No.2 on the humidity sensor connector (CN30).
30% 1.25V
40% 1.52V
50% 1.88V
60% 2.19V
70% 2.48V
80% 2.79V
(3) Fan motor
Fan motor
Relay connector
Protector
HWE13100
Abnormal
Open or short
3%
1 1
) }
273
(°C)[°F]
(k )
Measure the resistance between the terminals using a tester.
Motor terminal
or
Yellow
1
Relay connector
2
Gray
3
Brown - Black
Blue
4
Black
5
Brown - Blue
Orange
6
Blown
Black - Orange
7
Red
8
Red
Orange - Red 1
9
Orange - Red 2
50
40
30
20
10
0
-20 -10 0 10 20 30
-4 14 32 50 68 86
(A)
Normal Abnormal
1.98Ω
1.72Ω
1.10Ω Open or short
25.0Ω
7.92Ω
- 18 -
40 50
104 122
(at 20°C[68°F])
GB