I have an 83 brat with all the factory air conditioner components and having an issue getting the ac compressor to turn on... I can jump the power wire from the compressor to the battery and the compressor turns on... Connect the wire back to the chassis harness where it belongs and nothing happens... Checked all fuses and replaced any blown ones and still nothing... Any thoughts on what i could be overlooking???

I don't know that system specifically,  but there is a switch somewhere that enables / turns on a/c.  Then there are likely safety cutouts.  Usually at least an overpressure switch on the compressor output side, something to detect a locked rotor condition on the compressor.  Some have a thermoswitch on the evaporator to shut the compressor off when it is cold enough for conditions.  Any of these could be malfunctioning.   Really need a factory service manual for that model.  Or hopefully,  someone has dealt with it.

Low freon pressure.

Cabin fan turned on? If not then try that. 

Otherwise it could be a wiring issue behind the dashboard or an issue with the relays (RHS strut tower). 

Or as Naru2 said - not gassed enough. 

Cheers 

Bennie