Troubleshooting; Check Methods - Mitsubishi Electric CITY MULTI PFFY-WP20VLRMM-E Technical & Service Manual

[ VII Troubleshooting ]
VII Troubleshooting

[1] Troubleshooting

1. Check methods

1. Component and check points
(1) Thermistor
ŒRoom temperature thermistor (TH21)
ŒWater inlet thermistor (TH22)
ŒWater outlet thermistor (TH23)
Disconnect the connector and measure the resistance between terminals with a tester.
(Ambient temperature 10°C - 30°C)
Normal
4.3k - 9.6k
(Refer to the thermistor characteristic graph below.)
1) Thermistor characteristic graph
Low-temperature thermistor
ŒRoom temperature thermistor (TH21)
ŒWater inlet thermistor (TH22)
ŒWater outlet thermistor (TH23)
ŒThermistor R
= 15 k
0
ŒMultiplier of B = 3480 k
Rt = 15 exp { 3480(
0°C 15k
10°C 9.6k
20°C 6.3k
25°C 5.2k
30°C 4.3k
40°C 3.0k
(A) Temperature
(B) Resistance
(2) Fan motor (CNMF)
Refer to the page on "DC fan motor (fan motor/indoor control board)."
HWE12100
Abnormal
Open or short
3%
2%
1 1
) }
273+t
273
(°C)
(k )
50
40
30
20
10
0
-20 -10 0 10 20
(A)
- 9 -
30 40 50
GB