I have a 10 year old Lennox conservator II forced hot air gas furnace, the furnace itself runs good and produces heat , the problem I have is that the furnace cycle never ends it turns on produces heat then the firing stops the fan continues to run it cools down then before the fan cycle stops it calls for heat again and the ignitor clicks... for an unreasonable amount of time... then the furnace fires up again . When I replaced the thermostat the "swing was adjusted down to fix that problem but now its running like 21 hours out of 24 Any Ideas ? I'm thinking it's the fan switch but not sure of the location HELP

Make sure you check the thermostat to be sure the fan is not set to on instead of automatic.
Look on the door of the furnace blower for a wiring diagram. It will help you find the fan control.