Despite what you may have heard, there are actually honest, reputable furnace repair companies willing to provide quality service. Your best bet will be to ask around to find if anyone you know has had a positive experience and go from there. However, if that is not an option, the yellow pages will work just fine. Just make sure to get some background information on the process as a whole so you will be able to ask the right questions. In the worst case scenario you will encounter someone who is trying to get the best of you, but if he or she knows that you can't be had, they will have no choice other than to be straight with you.