Wah, I got stuck for more than half an hour on this sequence, I turned off the sound because I couldn't stand Anna's scream anymore but I finally made it. I hope there's not too much sequences like this, I prefer my p'n'c to be relaxing because I play them before going to bed :o)
So here's the solution :
Get the bear, look at it when it's in your inventory, take note of the number attached to it and keep in mind that the bear is upside down(165->591). At this point, you'll probably get "killed" by the monster.
Next round : go open the trunk with the code then go quickly under the bed. Now you have to do things in order : use the jar on the vent, left-click on the jar then use the peso on the vent.