an update on this problem as still not resolved:

I replaced shaft seal and dryer and took back to the shop for vacuum and refill but did not manage to replace the expansion valve (time constraints).

Shop told me it took a while to cool down but system was 'ok' and suggested I replace the pressure sensor. They also told me I could safely do this at home as there was a schraeder valve underneath.

They were wrong. The second I heard a 'whoosh' of pressure as I undid the valve, I got straight outta there and all the gas escaped (apologies to the environment).

New valve fitted, straight back to the shop for a recharge and they tell me it's still all ok but a little slow to kick in.

Few days on and I'm in 90F and not finding it cold enough (my 21yr old Jeep is colder). At rest, it appears to get warmer

So, fan is running ok, clutch is on (full time as I understand this is normal for a variable displacement compressor), new pressure sensor voltage is still 1.9v as before and the manifold reads 40psi Low and 150psi High.

Is the High reading too low given the high ambient? I am thinking there might be a problem with the compressor not compressing enough (I hear there is a pressure control valve inside)...

I am pretty stuck otherwise as the shops round my way just use a plug and play machine and are clueless when it comes to diagnostics....