Hello,

The first thing that I would reccomend is a recharge. The fact that you have only 17 psi at the port with the compressor off tells me that it is seriously undercharged. This will definitely keep your compressor from engaging (due to the pressostat that we talked about). The pressure at the test port with the system off should be approximately the same as the temperature outside(refrigerant pressure changes according to temperature). In other words, if it is a 65° day outside, you should have nearly 70 psi in the system with the compressor off and the pressures equalized. I would try charging the system (there is usually no need to jump the compressor; pressure will build on its own in the system from the refrigerant can). It may take a little while for the pressure to build on it's own enough to engage the compressor, but it will happen. Connect your refrigerant and gauges, open the valve to the system with the car running and the A/C engaged and the compressor will eventually engage. Run the system in recirculation mode with all windows down to provoke maximum cooling. Once you have charged the system, you can then check the performance. You'll want between 30-40 psi on the low side with the compressor running (higher on a really hot and humid day). Overcharged usually cools WORSE than undercharged, so try not to add too much.

Let me know if you need anything else...

Joe S. - Volvo Master Technician

1988 760 Turbo w/273k miles, 1981 242 Turbo w/243k miles