This might seem elementary, but here's a quick tip to defrost your windows faster. Most vehicles do this automatically, but some don't. When you have your defroster on, turn on your AC. Doesn't matter if it's cold outside; if it's too cold, your AC won't turn on anyway. However, if the temperatures are correct and the AC activates, you can speed your defrosting time by turning on the AC with the defroster. This dehumidifies the air before it comes out of the vents, and as a result defrosts the window quicker. With the automatic systems, the AC should come on whenever you turn on the defroster. This means if you have idle issues or perhaps a belt noise when you turn on the defroster, it's likely an issue with the AC and should be checked out. Here's a video on this topic.