astra aircon not working

[baz-r]

im trying to sort a fult on a 1999-2000 astra-G air con system
there is loads of pressure in the gas system (its a bit high realy on the low press side) but the compresor is not cuting in.
there is a amber light on the dash that looks like a fan in a header tank that goes out when the AC is on and flickers/flashes a few times when the ac is turned off
all the AC controle lights work on the buttons.

anyone got any info on this? (i have autodata 05) i know there a control unit but does any one know how to get a fult code out of it diy style?
i have a wiring digram
i suspect its some kind of sensor fault stoping it cut in

[baz-r]

turns out that the gas pressure on the low side was to high and to low on the high side (because the pump wasent cuting in so the guy @ lsuk said we will cheak it recharge it for free if it dont work after! £40 if it did
low and bhold he compressor was getting a good feed but the clutch winding was duff
so new compressor needed as it dosn't seem that i can just get the winding
any one know better?
looks like i will have to see if i can get a scrappy one if not!