Temperature Sensor; Thermistor; Low-Temperature-Range Thermistor; High-Temperature-Range Thermistor - Mitsubishi Electric CAHV-P500YA-HPB Service Handbook

[ 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 according to the instructions
detailed in section 2 "Checking the sensor status,"
andcheck 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.
TH1 . TH5
CN401
TH3 . TH7
CN402 3-4
TH2 . TH6
CN402 1-2
TH4 . TH8
CN404
. 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 dip switches and push switches to view the sensor reading on the LED.

(2) Low-temperature-range thermistor

: TH2,3,4,6,7,8,9,10,11,12,13

Thermistor

R
R = 15
50
40
30
20
10
0
-20 -10
HWE10060
*1
*2
No
Replace the thermistor.
*3
No
Check for proper connection.
Replace the control board.
TH9 CN405
TH10 . TH12
CN407 1-2
TH11 . TH13
CN407 3-4
= 15 kΩ±3%
0
1 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
0
(3) High-temperature-range thermistor: TH1,TH5
Thermistor
)}
110
100
90
80
70
60
50
40
30
20
10
0
40 50
- 124 -
R = 17 kΩ±2%
50
1
{ 4016 (
R = 17 exp
t
273 +t
30 60 90
Temperature( °C )
R = 7.465kΩ ±2%
120
1
R = 7.465
exp { 4057 (
t
273 +t
60 70 80 90 100 110 120
Temperature( °C )
1
)}
323
120
1
)}
393
GB