I have a Bryant gas furnace. About 2 days ago it was working fine. Yesterday I noticed it was very cool in my house. I checked the vents and they were blowing cool air. The fan stays on continuously. The pilot is lit and the filter is new. What are some possible causes and solutions to this problem?

Make sure the thermostat is turned on the heat and the temp set higher than the inside temp. Since you said you have a pilot lit your furnace must be one of the older models. Do you have the model number for the furnace? Is so post it.

Model # 394GAW000100

Check to see if you have 24 volts at the transformer, this model furnace will keep the fan running if it looses control power or if it goes off on one of the limit switches, look on the blower housing for a manual reset limit switch (may have a button between the two wires ) push in on the button, Good luck ,Mike