Came out to perform preventative maintenance on furnace for customer. Discussed with customer about maintenance, filters, and how the system has been doing overall. Customer stated the filters were already changed. Inspected the blower assembly, motor, capacitor, electrical components, heat exchanger, evaporator coil, burners, flame sensor, igniter, gas valve, inducer motor and overall condition of furnace. Cleaned flame sensor and inducer port. Heat exchanger has no signs of cracks at this time. Hot surface ignitor is still reading close to max ohms. Customer I checked thermostat operation, wiring, amps, temperatures and gas pressure. System is heating properly within manufactured specifications at this time.