My compressor doesn't run. There is freon (80psi) but the clutch doesn't kick in. What is the best way to jump the compressor to see if it runs ok so I can start checking the other wiring?

__________________
'83 300SD
'90 300D, 2.5 LITER
'96 FORD F250 POWER STROKE
'99 FORD F350 POWER STROKE