We purchase core(s) ( Not a used compressor )turn in your compressor core and get some VALUE The Core(s) returned  for refund MUST qaulify under these conditions( no exceptions ). :There must be no cracks or any other damage to the exterior case : The drive shaft of the compressor must turn smoothly at least three full revolutions. : The Core Must be indentical to the purchased compressor. : If a complete compressor was sold, then it must be return completed.( Clutch Assy. included ) If you determine that all of above qualifies then:- : Invoice number required, date of purchase ( Not older than 6 months ) : Call us at 1-626-443-1401 for core(s) value. : Call time Mon to Fri  8:00am to 5:00pm  California  time : Call tag service for pick up also available ( service charge will be subtracted from core price value )