Narrative:

We were dispatched with an inoperative trim air system due to trouble controling cabin temperature on ground. After takeoff; cockpit; cabin and pack output temperatures became impossible to control with temperatures fluctuating from very hot to very cold. I decided at that time to exercise my emergency authority/authorized and in coordination with maintenance control use the inoperative trim air switch to see if I could regain control of the temperature swings. We were able to lessen the variances by using the inoperative trim air system cycling it on and off based on ecs temperature values. This aircraft has had extensive history on this item and I believed it to be repaired at the time of dispatch. We refused the aircraft upon arrival in ZZZ.

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Original NASA ASRS Text

Title: A B757-200 FLT CREW WAS DISPATCHED WITH INOP TRIM AIR SYSTEM AND EXPERIENCED WIDE FLUCTUATIONS IN TEMPS. CAPT USED HIS EMER AUTHORITY TO TURN ON THE TRIM AIR TO REGAIN PARTIAL CONTROL OF COCKPIT AND CABIN TEMP.

Narrative: WE WERE DISPATCHED WITH AN INOP TRIM AIR SYS DUE TO TROUBLE CTLING CABIN TEMP ON GND. AFTER TKOF; COCKPIT; CABIN AND PACK OUTPUT TEMPS BECAME IMPOSSIBLE TO CTL WITH TEMPS FLUCTUATING FROM VERY HOT TO VERY COLD. I DECIDED AT THAT TIME TO EXERCISE MY EMER AUTH AND IN COORD WITH MAINT CTL USE THE INOP TRIM AIR SWITCH TO SEE IF I COULD REGAIN CTL OF THE TEMP SWINGS. WE WERE ABLE TO LESSEN THE VARIANCES BY USING THE INOP TRIM AIR SYS CYCLING IT ON AND OFF BASED ON ECS TEMP VALUES. THIS ACFT HAS HAD EXTENSIVE HISTORY ON THIS ITEM AND I BELIEVED IT TO BE REPAIRED AT THE TIME OF DISPATCH. WE REFUSED THE ACFT UPON ARR IN ZZZ.

Data retrieved from NASA's ASRS site as of May 2009 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.