I have a coleman evcon direct vent forced air furnace, the air is blowing cool air, everythinig else is working it's firing ,the fan is working

Exact model number?

If the unit is firing that means it is working and the flames are all lit so please rephrase so we can better understand what you mean. Also look on the control board and count the number of flashes and then look on the back of the furnace blower door and see what it says the number of flashes mean. Post that info also in your next post.

Natural or propane gas?

Regular home or mobile home. There is a difference .