Performed preventative maintenance on furnace for customer. Inspected the filters, blower assembly, motor, capacitor, electrical components, burners, flame sensor, ignitor, gas valve, pressure switch, safeties and overall condition of equipment. Ignitor was weak and was going to fail, so I recommended replacing it. Customer approved repair. I replaced the existing ignitor with a new one. Cleaned flame sensor and brushed dust off the burners and components. Checked thermostat operation, wiring, amps, temperatures and gas pressure. Adjusted gas pressure to proper levels. Recommended duct cleaning on ductwork due to amount of dust on the return and supply vents.