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9.0 DIAGNOSTICS & TROUBLESHOOTING
10.5 Checking Temperature Sensors
Diagnostics
The outdoor temperature sensor/thermistor uses a
scale of 10,000 Ohms at 77ºF (25ºC). This means,
a sensor exposed to 77ºF will show a resistance
of 10,000 Ohms +/- 1%. As the temperature
decreases, the resistance increases. Alternatively,
as the temperature increases, the resistance
decreases.
Measurements will be made with the sensor
disconnected from the control board. Again,
comparing the results must be done against a
calibrated tester.
A glass of water, mixed completely with ice
chips and given several minutes to settle should
measure 32 to 32.4ºF.
Apply resistance measurements to the chart found
below and compare to the control.
32º will have a resi/- 1% of 32,650 Ohms.
In the event Celsius is being used, the Fahrenheit
temperature will need to be converted.
º
C = (
º
F - 32) * 5 / 9
Example using 82
º
F
º
C = (82 - 32) * 5 / 9
º
C = (50) * 5 / 9
º
C = 250 / 9
º
C = 27.8
TEMPERATURE SENSORS:
Summary of Contents for A17 Series
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