no aux cooling fan

hi all 1986 2.3 16v no cooling fan have checked fuse ok i have 3 sensors on the thermostat housing which one (if any ) controls the fan. before i put power.through the one on the right appears? to be the heater gauge. the one in the middle has 2 wires.( me thinks ) one in for low temp . one out for high temp. one on the left(no idea) oh it is non air con.(as i live in england/??)car was on the ramps yesterday having laser tracking and it went to 120 degrees (ouch) regards ken