HORRIBLE burning plastic smell!!

I have a 2002 Venture (WB edition) that I got stuck this weekend. Managed to get it out, but since then, I have had a horrible (I mean, STINKS!) burning plastic smell that seems to come on when I have the heater/defrost on. I have searched under the hood, under the van, and everywhere else I can access to try and find the source. It seems to be coming from under the hood on the passengers side, though. I've had my nose literally in the engine, but can't figure it out. The heat and everything still works fine~I have noticed the temp runs a little lower than usual. Any suggestions??

I would check to see if you have crammed the lower radiator hose into the ac unit. The unit only spins when the ac or defrost is on, and since you only smell it when that is on I would check there.

Thanks! Good idea! I'll check that out today~