Indoor Service Manual

Specications are subject to change without notice. © 2016 Mitsubishi Electric US, Inc.
38
12-6. Trouble criterion of main parts
PVA-A12AA7 PVA-A30AA7
PVA-A18AA7 PVA-A36AA7
PVA-A24AA7 PVA-A42AA7
Room temperature
thermistor
(TH1)
Condenser/evaporator
temperature thermistor
(TH5)
Measure the resistance with a tester.
(Part temperature 10C (50F) ~ 30C (86F))
Pipe temperature
thermistor/liquid
(TH2)
Wiring diagram
Check method and criterion
Part name
Normal
4.3k~9.6k
Abnormal
Opened or short-circuited
Motor
Board with build-in motor
Current detecting resistor
Regulator Hall IC
Motor winding
Power
device
Pre
driver
Vm (Power supply for motor)
Vcc (Power supply for control)
Vsp (Speed command voltage)
PG (Pulse output for rotation)
GND
12-7. Thermistor
0
10
20
30
40
50
-20 -10 01020304050
< Thermistor for lower temperature >
Temperature
Resistance (K")
(˚C)
-4 14 32 50 68 86 104 122
˚F
<Thermistor Characteristic graph>
Room temperature thermistor (TH1)
Pipe temperature thermistor (TH2)
Condenser/evaporator temperature
thermistor (TH5)
Thermistor R0 = 15 k" ± 3%
Fixed number of B = 3480 k" ± 2%
Rt = 15exp { 3480( ) }
0°C (32°F) 15 k"
10°C (50°F) 9.6 k"
20°C (68°F) 6.3 k"
25°C (77°F) 5.2 k"
30°C (86°F) 4.3 k"
40°C (104°F) 3.0 k"
Thermistor for
lower temperature
1
273+t
1
273