hi Keith and welcome to the asylum
may i ask what year is urs plse , when u look at the suspension lever inside the landy , can u see a red line next to it
have u checked the fuses first
under the bonnet ,
F26 -20amp
F3 -5amp
FL10 -60 amp fuse
passenger side fuse box , F35 - 5 amp
also the relay , R7 , u can bypass this , is also in the engine bay fuse box, how old is ur compressor plse , have u had it plugged into a diagnostics
does the suspension drop overnight
if after you've checked the above, here is ur ch checklist
1/voltage at the compressor ,
2/ if no voltage , there are 3 x connectors behind the wheel arch cover, front passenger side , there known for wires failing in these connectors
plse let us know how u get on and can then walk u through it step by step , start with the fuses and relay and we can go from there
ref the dvd , see urs is the HSE, sorry can't help with that
@lynall or
@sierrafery may know, hope u didn't mind me tagging u
gary