Make sure that you buy raw pecans and not roasted or salted pecans to begin with. 2. Spread them in a single layer to roast. Do not overcrowd the air fryer basket or else they wont cook evenly and would not crisp up. 3. Allow them to cool completely and then store in the airtight container. 4. Even after that if the pecans does not feel crunchy then it means its not roasted enough. Roast for a couple of minutes more.