I drive an '86 240 and recently I noticed a strange noise under a strange set of circumstances. As you can tell from the subject line, the noise only seems to appear when I'm in reverse and have the A/C on, but am idling. In other words, I think it only happens when the car's engine is running at a very low speed, just above stall speed, and is in reverse. The noise sounds kinds like scraping of flapping of metal, maybe even grinding of some sort. Also, it doesn't seem to come from the engine or the A/C or even the hood area, but from underneath, like maybe the transmission? Any ideas would be greatly appreciated. Thanks in advance.