Technician arrived to perform a yearly friends and family club furnace maintenance on a 2011 Goodman furnace. Technician adjusted gas pressure, checked amps, checked static pressure, checked temperature differential, cleaned flame sensor, changed filters and insured proper operation. While changing the filter, technician noticed lots of dirt and debris in the ductwork getting into the system. Technician made options for the customer on getting them cleaned and sanitized. Recommendations have been emailed to the customer for further review. System is heating properly at this time.