Most likely you are a regular homeowner just like me and you are going to run into a problem with your furnace and you are not going to know what it is. First things first what you are going to want to do is on the bottom of most furnaces there is an inspection window, inside this inspection window there is a blinking light so if your furnace is running through a default it is going to send a signal to this light basically telling you what the problem is without having to tear it apart or having to hire a professional. Now inside here there is going to be a light that gives you two blinks, three blinks, four blinks and then a pause and so on and so forth. Once you diagnose that and figure out how many blinks it is you are going to want to go forth with taking your furnace apart. Now when you take these doors off you don't have to worry about your furnace having any problems where you get electrocuted or not because there is a safety switch built into these doors where they are pretty safe, take off our bottom door and inside this door installer service man they are going to tell us different things you might have problems with. Here it gives us the one blink, two blinks, three blinks, four blinks, five blinks or rapid continuous blinks and it is going to tell you the equipment problem and what you should check. Now there is going to be several other things you might want to check and of course you go through your diagram it is going to tell you what you should check, it could tell you gas pressure, you might live in the country, you might have an lp tank, maybe your lp tank is low. It has happened to me before, power problems, if you have a power problem the first thing you are going to want to check is make sure you have power to your furnace. Besides this switch there is also a built in fuse. Now if it is a bad fuse you are not going to get power to your furnace either. You will unscrew your fuse, check it, replace it if necessary, so on and so forth. We get so many calls on this you have no idea. Make sure your furnace filter is cleaned, replaced, not cleaned but replaced at least twice a year depending on where you live you might want to replace it more than that by gravel driveway or something, you get more dust in your house, if you are doing construction on your house you get lots of dust and you will want to replace it more often but for the most part this is your Bible to your furnace. It is going to tell you what is going to be wrong with it and how to fix it for the most part.