Can these be done with the compressor left on the car or is it a compressor out job to get to them?
I'd say yes it can be done in car, but access to the back/top of the compressor is obstructed by all manner of gubbins, and access is difficult. The pipes come from the front, under the compressor, up the back of it and then bolt to the top of it. To disconnect you have to get a torx in on a long extension from the top of the engine bay past all the wiring, air and water pipes.
Unless you can feel/see oil on the compressors rear/underneath, I'd leave it alone.
What is a safe psi to put into the system to test?
There is no safe pressure. Compressed air and R134a gas are supposedly explosive when mixed under some conditions. Your car, your rules, but don't come crying to me if it goes boom.
That said, IIRC the low pressure switch cuts out at about 2 bar/30psi, and the high pressure switch at 8 bar/120psi.
How much pao oi did you use and is it really necessary I thought I read some where that the gas already had oil in it?
I can't remember the exact numbers, but from memory, when new you're supposed to put roughly equal quantities (250ml?) of oil in the compressor, evaporator and condenser. I've never trusted the A/C places over the oil/gas mix, so prefer to do it myself. I'm not a qualified A/C tech though - even though I have got all the gear
