Troubleshooting - Mitsubishi Electric CITY MULTI Series Technical & Service Manual

7

TROUBLESHOOTING

7-1. HOW TO CHECK THE PARTS
PKFY-P24NKMU-E2.TH
Parts name
Room temperature Disconnect the connector then measure the resistance with a tester.
thermistor (TH21)
(At the ambient temperature 50°F~86°F)
Liquid pipe temperature
thermistor (TH22)
4.3k ~9.6k
Gas pipe temperature
thermistor (TH23 ,24)
Vane motor (MV) Measure the resistance between the terminals with a tester. (Coil temperature 68°F)
Red
M
Yellow
Brown-Red
Brown
Orange Green
Connect pin No.
Fan motor (MF)
Refer to 7-1-3.
Linear expansion
Disconnect the connector then measure the resistance value with a tester.
valve (LEV) (Coil temperature 68°F)
CN60
White
1
Yellow
2
Orange
3
LEV
Blue
White-Red
4
Red
5
Brown
6
7-1-1. Thermistor
<Thermistor characteristic graph>
Thermistor for
lower temperature
Thermistor R =15k
0
Fixed number of B=3480 ± 2%
Rt=15exp { 3480(
273+(t-32)/1.8
30°F 15.8k
50°F 9.6k
70°F 6.0k
80°F 4.8k
90°F 3.9k
100°F 3.2k
7-1-2. Liner expansion valve
Operation summary of the linear expansion valve
• Linear expansion valve open/close through stepping motor after receiving the pulse signal from the indoor controller board.
• Valve position can be changed in proportion to the number of pulse signals.
<Connection between the indoor controller board and the linear expansion valve>
Linear expansion valve
1
White
OCH518
PKFY-P30NKMU-E2.TH
Normal Abnormal
Open or short
Normal
- -
Brown-Orange Brown-Yellow
250 ± 7%
Normal
(1)-(5) (2)-(6) (3)-(5)
Yellow-Brown Orange-Red
200 ± 10%
Room temperature thermistor (TH21)
Liquid pipe temperature thermistor (TH22)
Gas pipe temperature thermistor (TH23) (TH24)
± 3%
1
1
) }
273
Blue
4
Brown
M
6
Yellow
2
5
3
Red
Orange
Check points
Refer to 7-1-1.
Abnormal
- -
Brown-Green
Open or short
Abnormal
(4)-(6)
Blue-Brown
Open or short
Brown
Red
4
Blue
3
Orange
2
Yellow
1
White
Connector(CN60)
14
< Thermistor for lower temperature >
50
40
30
20
10
0
-20 0 20 40 60 80 100
Temperature (°F)
Controller board
DC12V
6
5
Drive circuit
4
4
3
3
2
2
1
1
120