Hello I have an old coleman electric furnace in my home that isn't putting out any heat. It will only come on when I put it in manual and I have it set for heat. I know the blower works because it puts out plenty of air. Even with the thermostat put on over 70 degrees it still won't kick on by itself and when it is on there is no warm air. Also I know it's the original furnace of the mobile home but I don't know what year it is. I'm guessing early 90's. Do I need to replace the element in it or anything of that nature and if so how can I locate it. Thanks.