AU2 Aircon problem

[cpab]

G’day AU guys and in particular any aircon techs,
I'm looking for some tips to track down a problem with my aircon, which I’ve had for near on 6 years now.
It just stops cooling seemingly, when it feels like it. On a mild day in the mid 20s it works terrific and freezes your balls off, but as soon as the temperature gets into the 30s, the compressor cuts out and it blows warm air. Sometimes the compressor comes back on when the engine revs drop to idle, but this is not always the case, it is very difficult to analyse why it is happening.
The first summer we had the car, I got a mobile aircon tech to check it out, he couldn't find a fault.
Following year; local Ford dealership serviced and regassed the system. A month later it was stopping cooling at various times.
Following year; regassed again with dye; no leaks found, but was still stopping cooling occasionally.
Following year had it checked thoroughly, the tech showed me some metal fines in a small gauze filter, but didn't specify any problem it could mean. He regassed again. This did nothing to improve the problem.
Had it checked again at xmas 2010 and tech said he wouldn't charge me because he couldn't find fault.
When I asked him for any codes from the diagnostic, he gave me P1463. From this I found Aircon Pressure Sensor Insufficient Pressure Change.

I’ve read quite a lot on various airconproblem posts and thought I’d solved it when a US aircon forum member advised me that my symptoms were classic clutch gap. My clutch gap was about .5mm to.6mm, so I filed down the washer in there(because you can’t get the damn shimwashers anywhere), so my gap is now about 0.2mm.(I found the gap should be 0.16mm to about 0.35mm). This seemed to cure it, but as the summer got warmer, the compressor started cutting out again. It was better, but has got progressively worse this summer. Now it hardly works at all, after early morning.
I’m considering taking a chance on replacing the pressure sensor/switch. I've also been reading that the receiver/dryer/accumulator ought to be replaced, which I will now also consider replacing.
Is there any other part I should address while my system is down?

Any advice will be gratefully received.


Here's hoping. Cheers
Chris