For this job I performed a heating maintenance on a 3 year old AC Pro furnace 1. Found the flame sensor to be oxidized on arrival. Informed the customer that this is a common occurrence with her model of furnace. Informed that if not regularly maintained and cleaned, it can cause the part to go out. Because the sensor is a safety, if it no longer functions properly, the furnace will not be operational. For today I cleaned and reinstalled the flame sensor and ensured continued operation. 2. Replaced return filter with one provided by the customer. 3. Found no surge protection on the system, advised that if installed, it will act as a shield to the unit in the event of any sudden power surges which may be caused by things such as outage or lightning strikes. Customer has opted not to move forward with recommendations. System is operational upon departure. Thank you for choosing Cool Air Solutions.