I have a 1991 trane heat pump x147772p03. The heat and cooling works, but the fan never quits blowing unless I turn off the breaker. Today I changed the thermostat to a honeywell rth3100c. The wiring was difficult due to the lack of instructions so it may be wired wrong, but the fan still keeps blowing. Even though the heat will come on and go off the fan KEEPS BLOWING!!! Can someone tell me what I can do, or needs to be done to make the fan go off when it is supposed to?

My older house has a recently installed central heat/air, with gas heat. It works well enough, though the house doesn't have insulated walls, so the outer rooms are colder than the rest of the house. I have found that by creatively setting the dampers and running the fan in the on position instead of auto, the outer rooms are as warm as the rest of the house. Will it cost me much more per month to run the fan in the on position instead of auto? By the way, it is a 1000 sf house with two bedrooms, if the size makes a difference. The system does not serve my converted garage, just the original living space.