Mitsubishi Electric PCA-A24KA Service Manual page 25

9-6-1. Thermistor
<Thermistor Characteristic graph>
Room temperature thermistor (TH1)
Thermistor for
Pipe temperature thermistor/liquid (TH2)
lower temperature
Condenser/evaporator temperature
thermistor (TH5)
Thermistor R =15k ± 3%
0
Fixed number of B=3480 ± 2%
t( )Rt=15exp { 3480(
273+t
273+
0
10
20
25
30
40
9-6-2. DC Fan motor (fan motor/indoor controller circuit board)
Check method of DC fan motor (fan motor/indoor controller circuit board)
Notes
· High voltage is applied to the connecter (CNMF) for the fan motor. Pay attention to the service.
· Do not pull out the connector (CNMF) for the motor with the power supply on.
(It causes trouble of the indoor controller circuit
Self check
Symptom : The indoor fan cannot turn around.
Wiring contact check
Contact of fan motor connector (CNMF)
Is there contact failure?
No
Power supply check (Remove the connector (CNMF))
Measure the voltage in the indoor controller circuit
TEST POINT : V (between 1 (+) and 4 (-) of the fan connector): V
DC
TEST POINT
: V (between 5 (+) and 4 (-) of the fan connector): V
CC
Is the voltage normal?
No
Replace indoor controller board.
Check the operation
NG
Replace the fan motor.
1 1
) }
273
1 1
T-32
273
1.8
board and fan motor.)
Wiring recovery
Yes
board.
Replace the fan motor
Yes
Check the operation
Replace indoor controller board.
OK
END
<Thermistor for lower temperature>
50
40
30
20
10
0
-20 -10 0 10 20 30 40 50
-4 -14 32 50 68 86 104122 °F
DC294~325V
DC
DC15V
CC
OK
END
NG
25
°C
Temperature