Temperature Sensor; Temperature/Resistance Chart - Manitowoc QF0400 Service Manual

Electrical System

TEMPERATURE SENSOR

Function
The temperature sensor provides input to the control
board. The control board monitors the temperature
anytime the liquid line solenoid valve or compressor is
energized. When a temperature is sensed that is above
or below the correct temperature range, the ice machine
de-energizes.
Temperature Ranges:
QF400/QC700/QF800 155°F to 255°F (68°C to 124°C)
QF2200 30°F to 123°F
Specifications
10,000 Ohms at 77°F (25°C)
Use only Manitowoc thermistors.
Check Procedure
The thermistor must be securely attached and insulated
to operate properly.
Verify that the thermistor resistance is accurate and
corresponding to the high and low temperature ranges.
1. Disconnect the thermistor at the control board.
Connect the ohmmeter to the isolated thermistor
wire leads.
2. Using a temperature meter capable of taking
readings on curved copper lines, attach the
temperature meter-sensing device to the
refrigeration line next to the thermistor.
Do not simply "insert" the sensing device under the
insulation. It must be attached to and reading the actual
temperature of the discharge line.
3. With the ice machine running, verify that the
temperature of the refrigeration line (step 2)
corresponds to the thermistor resistance reading
(step 1) as stated in the temperature/resistance
chart.
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TEMPERATURE/RESISTANCE CHART

As the temperature rises at the thermistor block, the
resistance drops.
If the ohmmeter reads "OL," check the scale setting on
the meter before assuming the thermistor is bad.
Temperature of Thermistor
°C
-17.77° – -12.22°
-12.22° – -6.66°
-6.66° – -1.11°
-1.11° – 4.44°
4.44° – 10.0°
10.0° – 15.55°
15.6° – 21.1°
21.1° – 26.7°
26.7° – 32.2°
32.2° – 37.8°
37.8° – 43.3°
43.3° – 48.9°
48.9° – 54.4°
54.4° – 60.0°
60.0° – 65.6°
65.6° – 71.1°
71.1° – 76.7°
76.7° – 82.2°
82.2° – 87.8°
87.8° – 93.3°
93.3° – 98.9°
104.4° – 110.0°
110.0° – 115.6°
115.6° – 121.1°
121.1° – 126.7°
Revised 8/2003
Section 6
Important
Resistance
K Ohms
°F
(x 1000)
0° – 10° 85.35 – 62.46
10° – 20° 62.46 – 46.22
20° – 30° 46.22 – 34.56
30° – 40° 34.56 – 26.10
40° – 50° 26.10 – 19.90
50° – 60° 19.90 – 15.31
60° – 70° 15.31 – 11.88
70° – 80° 11.88 – 9.29
80° – 90° 9.29 – 7.33
90° – 100° 7.33 – 5.82
100° – 110° 5.82 – 4.66
110° – 120° 4.66 – 3.75
120° – 130° 3.75 – 3.05
130° – 140° 3.05 – 2.49
140° – 150° 2.49 – 2.04
150° – 160° 2.04 – 1.68
160° – 170° 1.68 – 1.40
170° – 180° 1.40 – 1.17
180° – 190° 1.17 – 0.98
190° – 200° 0.98 – 0.82
200° – 210° 0.82 – 0.70
220° – 230° 0.59 – 0.51
230° – 240° 0.51 – 0.43
240° – 250° 0.43 – 0.37
250° – 260° 0.37 – 0.33
Part No. 80-1214-3