The condenser coils are located outside so naturally, they're going to get dirty. They can also develop rust in some cases, and if they do, your response needs to be particular so that you don't have to replace this component and spend a lot of money.
Rust isn't like dirt that you can just remove pretty easily even after it has time to sit out. If you don't get to rusted coil sections quickly, then you can do serious harm to the coils' condition.
If you're like many people throughout the country, you rely on your furnace to keep your home warm and cozy during the cold months of the year. The last thing you want is furnace problems in the middle of winter. If you do notice that your furnace isn't working properly, you should contact heating services right away. Getting your furnace repaired sooner rather than later can prevent an emergency situation, such as your furnace going out altogether.