Arrived on site to preform a 20 point maintenance inspection on a 4 year old Lennox system. Upon arrival homeowner stated the system was producing white particles or air and she is getting sick, homeowner also stated the pure air pco system was not working as the thermostat was showing it not working. I listened to the customers concerns and headed up into the attic to identify the problem. Switched unit into heating and checked coil and supply and return plenum for anything that could be getting into the air stream, checked for tares in ductwork or any loose connections that may be sucking in dust or any other debris. All ductwork was secure and sealed found no tears or no indication that a foreign material had intruded into the system. Checked PCO UV filter rack, UV light was still on, Just a little loose, once secured fire air system reset itself and was fully Functional again. UV bulb is dim and is in need of replacement m homeowner is a aware and is also aware that the filter is d