After installation the sensor can be tested by cooling the sensor base with either ice (do not immerse the sensor in ice water, it is not water proof) or freeze mist. Locate the internal temperature sensor by first locating the indexing tab (see page 5 of the manual) and apply the mist to the base of the sensor on the opposite side of the indexing tab.
Once the unit is cooled continue by placing a drop of water on the moisture grid. If testing in the winter and the temperature is below 38°F (3.3°C), then simply placing a drop of water or a small amount of snow on the moisture grid will start a heating cycle. To stop the cycles, simply turn off the power for 5 to 10 seconds and then turn it back on.