Manitowoc Ice QF2200, QF2300, QF0800 Electrical System, Section, 6-52, TEMPERATURE SENSOR Function

Electrical System Section 6

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)

!Caution

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.

Important

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.

TEMPERATURE/RESISTANCE CHART

As the temperature rises at the thermistor block, the resistance drops.

Important

If the ohmmeter reads “OL,” check the scale setting on the meter before assuming the thermistor is bad.

Temperature of Thermistor		Resistance
		K Ohms
°C	°F
		(x 1000)
-17.77° – -12.22°	0° – 10°	85.35	– 62.46
-12.22° – -6.66°	10° – 20°	62.46	– 46.22
-6.66° – -1.11°	20° – 30°	46.22	– 34.56
-1.11° – 4.44°	30° – 40°	34.56	– 26.10
4.44° – 10.0°	40° – 50°	26.10	– 19.90
10.0° – 15.55°	50° – 60°	19.90	– 15.31
15.6° – 21.1°	60° – 70°	15.31	– 11.88
21.1° – 26.7°	70° – 80°	11.88 – 9.29
26.7° – 32.2°	80° – 90°	9.29	– 7.33
32.2° – 37.8°	90° – 100°	7.33	– 5.82
37.8° – 43.3°	100° – 110°	5.82	– 4.66
43.3° – 48.9°	110° – 120°	4.66	– 3.75
48.9° – 54.4°	120° – 130°	3.75	– 3.05
54.4° – 60.0°	130° – 140°	3.05	– 2.49
60.0° – 65.6°	140° – 150°	2.49	– 2.04
65.6° – 71.1°	150° – 160°	2.04	– 1.68
71.1° – 76.7°	160° – 170°	1.68	– 1.40
76.7° – 82.2°	170° – 180°	1.40	– 1.17
82.2° – 87.8°	180° – 190°	1.17	– 0.98
87.8° – 93.3°	190° – 200°	0.98	– 0.82
93.3° – 98.9°	200° – 210°	0.82	– 0.70
104.4° – 110.0°	220° – 230°	0.59	– 0.51
110.0° – 115.6°	230° – 240°	0.51	– 0.43
115.6° – 121.1°	240° – 250°	0.43	– 0.37
121.1° – 126.7°	250° – 260°	0.37	– 0.33

6-52 Revised 8/2003 Part No. 80-1214-3