Enjoy popcorn without oil or butter for a healthier twist on a movie theater snack. Hot air popped corn is not as enjoyable if you are burned by unpopped kernels flying from the opening of the machine. The type and condition of your kernels will determine if they pop completely or produce unpopped kernels. One hot air popper manufacturer, Presto, acknowledges that unpopped kernels can be thrown from the machine. Customers are advised to avoid the chute of the popper to prevent burns from the kernels.

The moisture level of the popcorn kernels before popping will determine if they pop completely. Popcorn kernels with less than 13 percent moisture are less likely to completely pop, according to Purdue University's horticulture department. When the kernels dry out to below 11 percent moisture, they might not pop at all. Adding moisture back into dried kernels to bring them back up to between 13 and 14 percent moisture does not bring the popped to unpopped ratio back to the original number. Popcorn kernels will pop best if they have never dried to a moisture level below 11 percent. For home use, only buy popcorn kernels in tightly sealed packages and use them before the use by date on the container. Do not store the popcorn in the refrigerator or freezer because these dry environments can encourage excess drying of the kernels.

Older kernels are more likely to have dried out than fresher popcorn kernels. This accounts for fewer kernels fully popping and more unpopped kernels being blown out of the hot air popper. Check the date on the container of popcorn to ensure that you are purchasing fresh kernels, and store the kernels in an airtight container at room temperature.

If your hot air popper is not popping kernels at all and only expelling unpopped kernels, a faulty thermostat in the appliance might be to blame. Disassemble the unplugged appliance and check the thermostat wiring with a voltmeter. Clean out the fan with compressed air to ensure it is free of debris that would prevent it from blowing hot air around the kernels. If you are unsure of how to disassemble and reassemble the popper, you might need to purchase a new popper.

Use new popcorn to avoid problems with old, stale kernels. Store your leftover popcorn kernels in an airtight container at room temperature to protect the moisture level. If your kernels dry out, soak them for one hour in water, drain and dry the kernels completely before putting them into the popper. Never use wet kernels or oil in a hot air popper. Change the brand of popcorn kernels you are using if you have checked the wiring and fan on your popper and nothing seems to be wrong.