What was found
AT 40000 FEET THE EMERGENCY PRESSURIZATION CAME ON FULL WITH THE SWITCH OFF. CREW IMMEDIATELY CHECKED THE CABIN ALTITUDE AND FOR ANY RATE OF DESCENT OF THE PRESSURIZATION. ALL LOOKED STABLE, THEN THE EMERG PRESS ON LIGHT CAME ON WITH A SLIGHT SMELL OF SMOKE IN THE CABIN. PILOT DECLARED AN EMERGENCY AND ASKED FOR AN EMERGENCY DESCENT AND ATC GAVE ME 25000. DURING THE DESCENT THE CABIN DESCENDED NORMALLY. WE ACCOMPLISHED THE EMERGENCY CHECKLIST AND THE SYSTEM RESET. SINCE EVERYTHING WAS LOOKING NORMAL I CANCELED THE EMERGENCY AND STAYED AT 25000 FOR FUEL. ABOUT 10 MINUTES LATER LATER IT ALL HAPPENED AGAIN AND WOULD NOT RESET SO I DECLARED AND EMERGENCY AND RAPID DESCENDED TO 4000 FEET, WENT STRAIGHT TO THE AIRPORT AND LANDED ON RUNWAY 14 AND TAXIED TO ATLANTIC. ACM WAS LATER DEFERRED AND AIRCRAFT FLOWN TO KMCO FOR MAINTENANCE. MAINTENANCE FOUND ERRATIC OHMS IN THE 450 DEGREE SWITCH IN THE ACM.