Package heat pump problem.?

3 ton package heat pump. Age 12, Copeland non-scroll compressor. R-22. All the fans and the compressor are running. Not capacitor problem. Getting proper voltage. System was evacuated and filled by weight with new refrigerant. System took the new refrigerant normally. Does not cool. Gauges on the low pressure side reads 150 with the unit off not running. With the unit running, gauge does not move. Showing no suction. The pipes around the compressor are not even sweating. It is on the cooling mode. Does anyone see a possibility except a bad compressor? This unit sat and not used for while, but not over a month. I don't need any WAG's. Hopefully an experienced heat and air person is reading. Also do not need to be told to call certified repair person. I can repair this if it is cost effective, if I can figure out the problem. Thanks, JA