AC high pressure on low side, High side normal?

We have a 2008 Aveo and the AC has begun blowing hot. We replaced the Expansion Valve, Vac'ed the system, recharged it and it is now showing 66psi on low side and the fan kicks on at 265 degrees high side and shuts off at 200 degrees high side. thermometer in the vents drops to its lowest at 78 degrees with fresh air. Could this be a bad check valve in the compressor? Bad High Pressure switch (not kicking fan on and off at proper times)? Bad Drier? really scratching our heads on this one...