Came out to perform preventative maintenance on furnace for customer. Discussed with customer about maintenance needed, filters and any issues. Customer showed me location of everything. I changed out 2) 14x30x1 filters in the home. Inspected the blower assembly, motor, electrical components, heat exchanger, coil, burners, flame sensor, igniter, inducer motor, gas valve, pressure switch and safeties. Cleaned flame sensor and dust off the burners and components. Found several hot spots on the heat exchanger and oil residue on the evaporator coil. Checked furnace operation, wiring, amps, temperatures and gas pressure. Adjusted gas pressure and made sure system completed heating cycle. Discussed with customer about systems condition and some concerns I had. Customer is aware of the condition of the unit and wanted me to send him updated numbers for replacement. I do advise customer have us back out to go over some code requirements and upgrades needed to help system if he would like to re