When you say, does not come on, does the display light up? if so check belt tension ac clutch etc. Might be ac clutch stiff and needs that bit extra to initial turn it, you need to see what is happening, an AC engineere would be able to fit guages to tell if the clutch is coming on or not, But you cannot so do the best you can, listen for it click on etc. More details if this does not help, Or change your silencer back to a quiet one.
SD, November 2012