The clutch was engaging when they were applying the gas, It was my fault it stopped working after
In my tiredness and spending the whole day in the hot weather in a black car with black leather and no aircon I found myself running out of steam and making silly mistakes, in INPA I noticed a new error under the AC, which was 'error 52: Energy saving mode', scratched my head for a while and realised that transport mode was enabled, disabled transport mode and the error cleared leaving no error codes under the AC and also the clutch now engages and disengages when controlling from the AC interface in the car, or in INPA.
I think what you just said though @upallnight confirms my suspicion, in that the compressor is done and needs replacing, Come to think of it the low lines were not even cold when running on max, and also when I was looking at the gauges in the garage after it had been filled, the PSI wasn't fluctuating with the AC on max which I would expect it to, I cannot remember the figures but if memory serves me correctly the low pressure should move between 25 to 40ish depending on the cycle....?
I have cancelled the order for the low pressure sensor, and ordered a new compressor instead with the hope I can put this one to bed and move onto the next job!