The compressor and dryer have been replaced, PAG 46 oil 5 oz added, vacuumed an hour, pressure has no change at -30 psi for another hour after stop, vacuumed 45 minutes again, added R-134A in 2 cans. The clutch didn't engage at all, using paper clip for the relay (pins 30+87) to force compressor on while adding refrigerant, which was working because I felt frozen cold on the low pressure line. However, it still doesn't work with the relay(new) and the pressure on both side is about 85 and 90 psi when using paper clip to force it engaged. Too little difference between the low and high lines. Please help for any possible reasons!