2003 Chevy silverado 2500HD pick up

The a/c won't blow cold air. only thing that's weird is that the low pressure hose has a high pressure. Anyone know why? Also replaced the drive ring on the compressor.

 

Was the system recently worked on? Does the compressor engage? If so the compressor is not pumping indicating a replacement is needed or if system was opened up it's possible that it wasn't properly evacuated before being recharged. If compressor does not engage, check all plugs in system and you can check for power at compressor. If you still haven't found the problem please post with procedures done and results.