why want a/c compressor come on with new compressor, condenser, and expansion valve, with good relay and fuse, and system full of Freon?

This testing will take all of 10 minutes tops!

All fuses inside and under hood are good.

You stated jumping relay engages compressor - does the low side metal line and receiver drier get *COLD* while compressor is operating? The larger refrigerant line - when compressor is working - that line should be COLD to the touch - - IF that line is not COLD - problem is still under the hood ! Think about it - when relay is jumpered - you are bypassing the HVAC control all together - low pressure line should get COLD regardless. This is just to test the systems functionality ‘mechanically’ .. Electrical controls are bypassed.. Now if that line is indeed COLD to the touch - THEN there may be a problem electronically or within the cabin HVAC components. Good luck!