I noticed cotton wood seeds (fuzz) flying through the air in my neighborhood today. Now is a good time to schedule your Spring?Summer HVAC cleaning and maintenance. Watch for fuzz flying in your neighborhood and schedule your cleaning once it is gone. Usually cottonwood fuzz only flys for a week or two each spring. If you clean your unit too early and you have cottonwood trees nearby then your outdoor coil can become clogged and stress your a/c unit over the summer.