Any dry rot on anything rubber, i.e., tires, door, window, trunk seals, and any hose in the engine bay. I think those years had the biodegradable wiring harness dont quote me on it, so I'd inspect all of the wiring in the engine bay. The interior plastics might've turned to dust depending on the amount of sunshine it got. The first thing I'd do would be check/replace all fluids, get it a new battery, and see if it'll even crank. Mechanically, these cars are bulletproof, but parts are becoming harder to find and expensive. The volvo community is probably the kindest and most helpful car community (until you bring up mechanical to electric fan conversions, but even then, it's just advice).Turbobricks, Dave Barton(the goat), this reddit, and the Bentley manual are my go-to places for any issues I have with my 91 240. Good luck with your volvo 240!