What was found
FLIGHT 857 DURING CLIMBOUT FROM MIA FLIGHT CREW REPORTED AIRCRAFT WOULD NOT PRESSURIZE & IT SEEMED BOTH PACKS WERE NOT WORKING AT ALL. AIRCRAFT RETURNED TO MIA & LANDED WITHOUT ANY FURTHER INCIDENT. MAINTENANCE CHECKED BOTH LEFT & RIGHT PACKS IAW B-727 MM CH 21-55-0 OPERATION CHECK WAS NORMAL. MAINTENANCE RERACKED THE PRESSURE CONTROLLER & CLEANED PACK VALVES & CLEANED THE CANNON PLUGS & RESECURED, A FULL PRESSURIZATION CHECK OUT WAS ACCOMPLISHED IAW AMERIJET WORK CARD 847 OPERATIONAL CHECK WAS NORMAL. AIRCRAFT WAS RETURNED TO SERVICE.