David Deem 714-997-3486 Dave@DeemTeam.com By Anita Ginsburg During any season when you need to use your furnace, the last thing you want is to have it malfunction. The thing is, even if you schedule regular maintenance and keep your unit clean, there are still some issues that can go from bad to worse quickly. Here are four common furnace issues that are more dangerous than you may think: Dirty Air Filters Although quite common, and easy enough to swap out, dirty air filters can do a lot of damage. Over time, your furnace will have to work harder and cycle more often. In addition to higher utility bills, this can lead to other parts in the furnace breaking down more quickly than they otherwise would. Clogged air filters can also make you sick. Over the course of several months, trapped dirt and debris from the filter can contaminate indoor air, dramatically reducing its quality. It's not uncommon for people to develop respiratory issues, sometimes severe ones. Always kee...