Furnace maintenance. Cleaned and serviced furnace. Tested inducer motor, pressure switches, ignitor, gas valve voltage and pressure, flame sensor, blower motor amperage and capacitor. Thermostat and heat exchanger. Replaced safety flame sensor due to corrosion. When the furnace's gas valve opens, the sensor generates an electrical current to confirm the presence of a flame. If the sensor doesn't detect a flame, it shuts off the furnace to prevent a gas leak. Everything else is in adequate working condition for furnace age. Replaced furnace filter that customer provided. Customer will have one more VIP visit remaining for 2025 cooling season.