Goeff:
I am assuming you have a set of gauges. If you have a sight glass thats even better. If you don't have a sight glass you can charge slowly and watch the temp. Once you get enough refrigerant the system will stabilize and if you charge too much will start to rise. I would say a hi of about 250-300 psi. on the high side, even more with higher ambient temps. The low side should go about 30-40 psi. This should be done off idle about 1500 rpm to make sure you are getting max compressor output. Also make sure your condenser coil is getting plenty of fresh air as this will affect efficiency and maximum cooling, and your head pressure will be higher, if need be put a small fan in front of it to simulate movement at road speed.
These are all estimates, but should get you in the ball park.
Good Luck
Phil
