if i see that diagram again ill scream,lol,ive been studying that for the last couple of weeks now,i know it blindfold, the way i see it is that the on off switch supplies a signal to the de ice switch this in turn goes to the pressure switch which then sends it to the ecu pin 21,the w/o t relay relys on this signal to stay closed and keep a/con running,if the a/con is turned off or the de ice switch shuts down due to it being too cold then the signal to ecu is cut which should earth out the w/o/t relay via pin 12 and shut sytem off,the only way of controlling the system is by earthing the w/o/t relay,i assume the ecu senses when there is a w/o/t applied to the car also and earths it out in the same way as well, my chip isnt allowing it to earth out,im going to try another chip which is deffo a/con compatible,although harvey reckons mine is?i could fit another relay and bypass the ecu totally but would prefer it to work as it should now ive come this far