A B737 PERFORMS A RETURN AND LAND AT ORLANDO WHEN THE FLC IS UNABLE TO COOL DOWN A VERY HOT CABIN.

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DURING TAXI OUT ON 1 ENG; BOTH PACKS ON; CABIN CREW INFORMED US CABIN TEMP WAS GETTING WARM. AIRPLANE WAS FULL; 119 PAX; OUTSIDE AIR TEMP 88 DEGS F. DIRECTED FO TO SELECT FULL COLD ON BOTH AIR CONDITIONERS; AND STARTED REMAINING ENG FOR TKOF. OBSERVED BOTH AIR MIX VALVE INDICATORS TOWARD FULL COLD AND DUCT TEMP DROP FROM 90 DEGS F TO 70 DEGS F. TKOF AND DEP UNEVENTFUL. HOWEVER; PASSING AT 3000 FT MSL; FLT ATTENDANTS INFORMED US THE CABIN WAS GETTING EXTREMELY HOT. DIRECTED FO TO SELECT FULL MANUAL COLD. OBSERVED WARM AIR EXITING GASPER AIR DUCTS AND DUCT TEMP INDICATED 120 DEGS F WITH BOTH MIX VALVES STILL INDICATING FULL COLD SELECTED. DIRECTED FO TO CHK CIRCUIT BREAKERS AND PLT OPS MANUAL. PLT OPS MANUAL HAD NO RELATIVE GUIDANCE FOR THIS FAILURE. WITH NO CTL OVER CABIN TEMP; REQUESTED RETURN TO MCO AT APPROX 20 MI N OF MCO; PASSING 11000 FT. NOTIFIED COMPANY; PAX; AND MAINT. DURING DSCNT WITH LOW PWR; OBSERVED DUCT TEMP AT 75 DEGS F AND CABIN TEMP AROUND 90 DEGS F. BOTH MIX VALVES STILL INDICATED FULL COLD. VISUAL APCH AND UNEVENTFUL LNDG ACCOMPLISHED. UPON RETURN TO GATE; DIRECTED IMMEDIATE GND AIR CONDITIONING FAILURE AND SVC DOORS OPENED FOR RAPID COOLING. PAX WERE ALLOWED TO DEPLANE WHILE MAINT EVALUATED ACFT. ON INSPECTION; MAINT DISCOVERED THE 35 DEG CONTROLLER AND SENSOR HAD FAILED ON THE R AIR CONDITIONING PACK. IN ADDITION; THEY DISCOVERED THE AIR CYCLE MACHINE ON THE L AIR CONDITIONING PACK FROZEN/SEIZED. THIS RESULTED IN NO COLD AIR AVAILABLE TO CTL CABIN TEMP. ACFT WAS ACCEPTED ON A 30 MIN TURN WITH NO DISCREPANCIES LOGGED. MAINT REPAIRED R PACK AND PLACARDED L PACK INOP. ACFT RE-DISPATCHED TO DEST.