Yes Sir that´s it, no more than 1 degree up/down, thanks i´ll work on that know.You need to feed the Lm35 into pin 2 of the Lm358, and the temperature reference on pin 3, using an npn transistor on pin 1, then as the temperature rises above the level, the output will turn off the relay, and cool down to the lower level, then switch on, voltage levels are 375mV on 380mV off,
the hysteresis is only 5mV.
thats. 37.5C to 38C