The invention provides a self-contained automatic temperature-responsive three-way line valve. A tubular valve member is axially slidable between first and second limit positions for selectively directing fluid from an inlet port to a first outlet port or a second outlet port. The valve member is disposed between a pair of opposed compression springs, one being a conventional spring biasing the valve member to the first limit position and the other being an SME spring which overcomes the bias of the first-mentioned spring when the fluid exceeds a given temperature.