Hello if it is the newer shape scienic u have its probably the resistor that controls the fan speeds.If the heater will not blow on any speeds the air con will not switch on without the fan blowing.(usually the ones wth digital heater controls).This is under the centre of the dash but can be replaced by removing just the instrument cluster and shoving your arm in to get to it.This type has no modified wiring and is only held in by a single torx 20 screw,hope this helps,contact no. 07919146276
CHRIS HART, September 2010