First hot day of the year and surprise surprise, the aircon doesn't
work. Anybody here worked on one of these? It's a 98 S plate with
the 1.8 engine.

I've traced it as far as the compressor solenoid / clutch / whatever
isn't getting any power when the A/C is turned on. The light comes on
on the dash, but the wire going to the compressor is dead (checked
with a test lamp and voltmeter). All the other heater functions work
OK, and the fuses (there seem to be three associated with it) are all
intact.

If I run a wire directly from the compressor to the battery I can hear
a 'clunk', the idle drops a bit, and it starts to blow cold - so it
looks like wiring / relay / control PCB fault. Any pointers for
getting at the heater controls, preferably without pulling the entire
dash out?

Even after running it for 5 mins with the wire to the battery it was a
bit feeble - so it'll probably need a re-gas as well sometime soon.
Anybody tried the £30 kits you can get from Halfords etc? Or would I
be better off going to an aircon specialist to get this bit done?