This past Saturday, I took my '89 240 DL out a couple of times for tests run with the overdrive off. The first time, I drove her 24 miles total without the A/C or fan on, windows down the whole time, & stayed under 55mph. She handled just fine, gave me no problems or issues. Later than day, I drove 60 miles (gotta love those family get togethers), but since I had my daughter in the car with me, I ran the A/C. 15-20 miles into my drive, I noticed that the A/C wasn't as cool any more & that there was a kind of musty smell coming from the vents. I was doing just under 60mph & I had the overdrive off. I turned the A/C off, rolled down the windows, & continued my drive. I turned the A/C back on a mile from my destination & it worked fine. I drove home several hours later with the overdrive & A/C off with no problems.

Then on Sunday, I turned on the car to move it so he could work on his vehicle & noticed a horrific screeching/grinding/metal-on-metal noise coming from under the hood. I popped the hood, but could see nothing obviously wrong. The overdrive was on & the A/C was off, since I was only pulling forward about a carlength. I didn't turn the car on again for the rest of the day.

This morning, I got in the car & started her up. The screeching/grinding/metal-on-metal noise was still there. The car was in park, just made this noise as soon as I started her up. Having no other choice, I went ahead & drove her in to work.

The noise was there the whole time. It sounds kind of like something is loose and not seated properly, but I have no idea where exactly the noise is coming from. I drove with the overdrive & A/C off, never got above 60mph. About 3 miles from work, I heard a thump followed immediately by a whack from under the passenger side of the hood while I was driving. I was certain that something like a belt had just snapped, or that something under the hood had come loose & flown off. But when I checked under the hood, I could find no evidence of any damage whatsoever. No snapped or frayed belts are visible, there's no sign that anything happened at all. But that noise is still there. It doesn't get any better or worse if I'm driving, idling, parked, whatever. If the car is on, it's grinding.

I recently had a retrofit done on my A/C. Could it be the compressor making that noise? Could I possibly have damaged the compressor by running the A/C without overdrive on at 60mph for an extended period of time?

I thought perhaps it could be the oil, but I checked that as well & I'm fine on oil. No metal shavings are present on the dipstick, but I guess I would have to actually change the oil to see that anyway. Is it possible that this is another new issue with the transmission?

I know I'm asking a lot of questions, but I'm not sure where to even begin with this. I'm worried that this grinding is doing some kind of internal damage to the engine or transmission. Has anyone else had this kind of problem before? What did the problem end up being?

Should I just park the car until I can get some time to look at the problem & figure out what the heck the problem is, or is it okay to drive in this condition? Any & all advice is most welcome.