AN MD80 IN CRUISE AT FL350 DECLARED AN EMER AND DIVERTED DUE LOSS OF CABIN PRESSURE CAUSED BY THE R AND L PACK FAILURE.

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WHILE IN CRUISE AT FL350; FLT ATTENDANTS CALLED TO COMPLAIN THAT IT WAS COLD IN AFT CABIN. AT THE TIME BOTH PACK TEMP CONTROLLERS WERE IN AUTO AND BOTH INDICATED 110 DEGS DUCT TEMP AND 72 DEGS CABIN TEMP. FO SELECTED A HIGHER AUTO SETTING ON R PACK BUT 2 MINS LATER FLT ATTENDANTS AGAIN CALLED TO SAY THAT IT WAS GETTING EVEN COLDER. R TEMPS REMAINED THE SAME; SO FO TURNED TEMP UP AGAIN WITH NO EFFECT. WHEN FLT ATTENDANTS CALLED A THIRD TIME; HE WENT TO MANUAL ON R PACK IN AN EFFORT TO GET IT TO MOVE UP FROM 110 DEGS BUT IT IMMEDIATELY JUMPED TO 150 DEGS -- FULL SCALE. ALL ATTEMPTS TO LOWER TEMP FAILED; SO WE INITIATED A DSCNT TO FL240 IN ANTICIPATION OF LOSING THE PACK. AS WE DSNDED; THE R PACK DID TRIP OFF AND THE CABIN ALT STARTED A CLB OF AT LEAST 1500 FPM -- FULL SCALE. AT FL240 THE CABIN CONTINUED TO CLB; NOW PASSING 10000 FT; SO WE DECLARED AN EMER AND CONTINUED DSCNT TO 10000 FT MSL. DURING THE DSCNT; THE CABIN PASSED THROUGH 14000 FT WHICH INITIATED THE PAX OXYGEN SYS. ALL ATTEMPTS TO RESTORE PACKS FAILED. ATC INDICATED THAT AMA WAS THE CLOSEST SUITABLE ARPT TO OUR LOCATION; SO WE PROCEEDED THERE AND EXECUTED AN UNEVENTFUL APCH AND LNDG. PAX WERE IMMEDIATELY XFERRED TO AN OUTGOING DFW FLT AND LATER THAT NIGHT THE FO AND I FERRIED THE ACFT TO ZZZ. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE DIRECT CAUSE OF THE LOSS OF CABIN PRESSURE WAS THE FAILURE OF THE R AND L AIR CONDITIONING PACK SYS. THE RPTR SAID THE R PACK TRIP WAS CAUSED BY AN OVERHEAT CONDITION BUT THE CAUSE OF THE L PACK MALFUNCTION IS UNKNOWN. THE RPTR SAID MAINT DOES NOT ROUTINELY FEEDBACK INFO ON THE MALFUNCTIONING COMPONENT OR REPAIR ACCOMPLISHMENT.