What was found
DURING CRUISE FLIGHT, THE PILOTS NOTICED THAT THE RT ENG AIR-CONDITIONING PACK WAS ILLUMINATED IN WHITE RATHER THAN GREEN INDICATION. THEY TRIED TO RESET THE PRV & IT REMAINED WHITE, OFF. THE SYS WAS ABLE TO BE PUT ON MEL BUT THE DECISION WAS MADE TO GO TO THE NEAREST MFG SERVICE CTR & HAVE IT CHECKED. THE ACFT RETURNED, IN DECENT THE SYS TURNED GREEN & OPERATED CORRECTLY. THEY LANDED WITHOUT INCIDENT. THE SYS WAS CHECKED & VERIFIED TO OPERATE NORMALLY. THEY COULD NOT DUPLICATE THE ISSUE & THE ACFT WAS RETURNED TO SERVICE. THE TRIP CONTINUED WITHOUT INCIDENT.