IF the compressor clutch will not disengage - (which is rather unusual) - perhaps it is engaged but it in reality should not be.
Too many variables for online diagnosis - recommend seeking *hands-on* assistance from qualified personnel.
RepairPal Certified shops can diagnose and repair your 1997 INFINITI Q45. They provide transparent pricing with a minimum 12-month or 12,000-mile warranty on repairs and services.
Compressor is operating for apparent reason - system undercharged but compressor clutch malfunction exist.