Narrative:

During taxi out on 1 engine, both packs on, cabin crew informed us cabin temperature was getting warm. Airplane was full, 119 passenger, outside air temperature 88 degrees F. Directed first officer to select full cold on both air conditioners, and started remaining engine for takeoff. Observed both air mix valve indicators toward full cold and duct temperature drop from 90 degrees F to 70 degrees F. Takeoff and departure uneventful. However, passing at 3000 ft MSL, flight attendants informed us the cabin was getting extremely hot. Directed first officer to select full manual cold. Observed warm air exiting gasper air ducts and duct temperature indicated 120 degrees F with both mix valves still indicating full cold selected. Directed first officer to check circuit breakers and pilot operations manual. Pilot operations manual had no relative guidance for this failure. With no control over cabin temperature, requested return to mco at approximately 20 mi north of mco, passing 11000 ft. Notified company, passenger, and maintenance. During descent with low power, observed duct temperature at 75 degrees F and cabin temperature around 90 degrees F. Both mix valves still indicated full cold. Visual approach and uneventful landing accomplished. Upon return to gate, directed immediate ground air conditioning failure and service doors opened for rapid cooling. Passenger were allowed to deplane while maintenance evaluated aircraft. On inspection, maintenance discovered the 35 degree controller and sensor had failed on the right air conditioning pack. In addition, they discovered the air cycle machine on the left air conditioning pack frozen/seized. This resulted in no cold air available to control cabin temperature. Aircraft was accepted on a 30 min turn with no discrepancies logged. Maintenance repaired right pack and placarded left pack inoperative. Aircraft re-dispatched to destination.

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Original NASA ASRS Text

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

Narrative: 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.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.