Responded to a report that the furnace blower fan would not turn on when manually activated at the thermostat. Upon inspection, found that the thermostat was wired with only a two-conductor cable, which does not support independent fan control. With approval, replaced the thermostat wire between the furnace and thermostat with a six-conductor cable. Secured the new wire along the existing Romex and fastened it to the wall for proper support. Tested operation and confirmed that the blower fan now turns on and off correctly when controlled from the thermostat and operates automatically with the burner as intended. Identified a minor oil leak at the oil tank filter assembly and tightened both the filter nut and bleeder nut to stop the leak.
