The AC power relay is located behind the right side of the dash on a 1991 Chevy Corvette. It is on top of the plenum.
in back on top by distributor, or down on driver side engine block on the side by the bellhousing, look for wires and round unit threaded into the block.
The oil temp sensor on a 1991 Chevy Corvette is located on the bottom of the engine, near the oil pan. It constantly monitors the temperature of the oil and relays information to the computer.
Mounted next to the oil filter.