Came out to perform preventative maintenance on furnace. Discussed with customer about maintenance, filters, and any issues. Customer stated that the filters need to be change, but other than that, just need the maintenance done. I changed the filters inside home for customer. Inspected the blower assembly, motor, capacitor, electrical components, heating components, evaporator coil, heat exchanger and overall condition of equipment. Found the insulation in the evaporator coil box was coming off and blocking the coil. I used adhesive spray to put it back in place. Cleaned flame sensor and dust off the burners and components. Checked system operation, amps, temperatures and gas pressure. System is operating properly at this time.