Mitsubishi Electric e Series Service Handbook page 141

[ IX Troubleshooting ]
Solenoid Valve
-3- Temperature sensor
Use the flowchart below to troubleshoot the temperature sensor.
Troubleshooting the thermistor
Start
Disconnect the thermistor to be checked from the circuit board.
Measure the actual temperature of the pipe at the thermistor.
Check the thermistor resistance.
Compare the actual temperature and the temperature that corresponds
to the thermistor resistance to see if there is a discrepancy between them.
No temperature difference
Yes
Connect the thermistor connector to the circuit board,
check the sensor reading and check the temperature
difference.
No temperature difference
Yes
Normal
* 1 The table below shows the thermistor numbers and their corresponding connectors.
Check each sensor by disconnecting the corresponding connector.
TH11 . TH21
CN401
TH5 . TH25
CN408 1-2
TH1 CN407 1-2
TH7 . TH27
1-2
CN406
. Pull out the sensor connector from the I/O board.
* 2
Do not pull on the lead wire.
. Measure the resistance with a tester.
. If the measured value is within ± 10% of the value as shown in the table below, the circuit sensor is normal.
* 3 Use the maintenance tool to view the sensor reading.
(2) Low-temperature-range thermistor
: TH1,2,3,5,6,7,10,25,26,27
Thermistor R
R = 15
50
40
30
20
10
0
-20 -10
HWE1417B
*1
*2
No
Replace the thermistor.
*3
No
Check for proper connection.
Replace the control board.
TH6 . TH26
CN404
TH10 CN405
TH3 CN407 3-4
TH2 CN406 5-6
= 15 kΩ±3%
0
1
exp
{ 3385 (
t
273 +t 273
0 10 20 30 40 50
Temperature( °C )
(1)Thermistor <Heatsink temperature> :THHS
Thermistor
160
120
80
40
0
(3) High-temperature-range thermistor: TH11,21
Thermistor
1
)}
110
100
- 132 -
R = 17 kΩ±2%
50
{ 4016 (
R = 17 exp
t
0 30 60
Temperature( °C )
R = 7.465kΩ ±2%
120
R = 7.465
{ 4057 (
exp
t
90
80
70
60
50
40
30
20
10
0
40 50 60 70 80 90 100 110 120
Temperature( °C )
1 1
)}
273 +t 323
90 120
1 1
)}
273 +t 393
GB