Upon arrival, David mentioned a clicking noise coming from the furnace. Inspection shows that blower wheel blades has loosened from the center wheel. Blower wheel blades are skipping on the center wheel causing the noise. Blower wheel will need replaced. Performed cleaning portion of preventative maintenence inspection. Clean flame sensor and check ignitor. Visual inspection of burners. Flush condensation trap and drain lines. Replace #35 water panel in humidifier and set water flow. 20x25x4 air filter in decent condition. Check again in 1-2 months. Test unit in heating mode from thermostat. Did not check temperature rise as an accurate reading is not possible with current faulty blower wheel.