yeah i thot it was an airlock when i had the random rising up & downs, so i topped it up and bled it. no probs for a few days then fitted the actuator and this happened! tbh, i dont think the fan did kick in which is why it would explain the sudden rise when i put the foot down..but shudnt the coolant cool it sufficiently/or at least a tiny bit without the fan? gona test the switch in the morning.. (by removing the white plug it shud come on am i correct lads?), then check the fuses becos the fan was definately working before i fitted the actuator and i didnt touch the connection