I've had exactly the same problem. The tear drop symbol flashes red, the iron heats up but when I press the steam release button, there's no noise of the air pockets being eliminated nor any steam coming out. I too bought mine 18 months ago and therefore it's out of warranty. I thought it may be a problem with limescale but of course, you can't place descaler in the chamber as you can't switch it on. If you hear of anything, please post it!
Miffysmithy, July 2009