The air-con unit in my bedroom had a surprise for us when we woke up this morning. When I turned it off, there was a small waterfall coming out of the vents, drenching my headboard. Then it made some odd cracking noises that went on for more than a minute, which prompted an investigation. As I lifted off the faceplate, a glorious sight greeted me. Completely covering the vents and sealing the filters in place was a layer of pristine white frost, smooth and perfect like the first snowfall. My air-con literally froze up overnight, and I'm at a loss as to how it happened, and whether it could happen again.

Should I call the maintenance guy again?