How to Change From A 2 wire thermostat to a 3 wire So I can Have fan only when needed

Since you didn't bother to offer up any info:

Do you at least 3 stat wires coming from the wall? If not then you will have to pull more stat wire.

Does your current stat have a "G" terminal?

How to Change From A 2 wire thermostat to a 3 wire So i can Have fan only when needed



Run yourself another tstat wire,from furnace to tstat

If your furnace is not desinged to accommodate Air Conditioning here one suggestion.

Have a thermostat that has a fan on and auto positions. Have three wires running from the furnace to the thermostat, and you will have to have a relay that the thermostat operates to turn on the fan motor.