You are close to normal, but my guess is that you are about 1/2 to 3/4 pound low on 134a. The system should have 1.6 Lbs. The low pressure switch, located passenger side on the fire wall where the two A/C lines go into the car, cuts in at 3.1 bar +/- .15 bar and cuts out at 1.6 bar +/- .1 bar. Thats about 40 high 20 low. With the car running and the hood up with you looking down at the clutch on the compressor, reach over under the plastic cover for the throttle and rev the engine up to abot 2000 rpm (by ear) and see if your clutch begins cutting in and out, if it does then you are low on 134a. In order to read the high pressure on your car you need to hook up a Volvo Scan Tool (VST). The high pressure reading comes from the linear pressure switch located just forward of the low side fill connection. If you are low on 134a, it would be a good idea to evacuate the system and charge it with the correct amount and tracer dye to help you find the leak with a black light. There is a general post for 850 A/C at the below link.