Narrative:

On our flight; during cruise and approximately 90 minutes into the flight. Both [the] first officer and I experienced a very noticeable change in ambient noise level (mostly cabin fan circulation); we both looked at each other as if we were asking; 'what was that sudden change in noise level?' almost immediately and without any warnings; cautions or ECAM messages; we experienced and sudden and dramatic change in cabin temperature through the entire aircraft. Cockpit registered a max temperature of 110 and the entire cabin was fast approaching 100.we did not have any noted malfunctions. I decided to turn the hot air valve off to see if that would help; but it didn't; the temperature kept on rising and getting hotter; I decided to divert. We communicated our intentions with ATC and dispatch. ATC asked if we [needed priority handling] and we said that we just needed to do a precautionary landing and that it was not an emergency at that moment. Our dispatcher asked if we wanted to communicate with maintenance and I declined; mainly because the extraordinary task loading that we have at the moment (coordinating with ATC; company; flight attendants and communicating with passengers).as we started making preparations for landing; we also did some amount of troubleshooting. The hot air valve being off; seem to alleviate the problem momentarily; but the hot temps returned again even with it off. We isolated air pack 1 also because it was indicating higher than normal temperatures. This seem to also alleviate the problem to a certain extend but we were still uncomfortably hot in the flight deck (98) and was about 94 in the cabin. We continue with our plan to divert and we needed to burn excess fuel to meet max landing weight. We descended to lower altitudes and extended the gear as well as started the APU and the use of spoilers to burn more fuel. ATC [was] super accommodating with delaying vectors. By the time that we were on final approach; the temperature was back to normal. We landed uneventfully and taxied to the gate. Passengers and bags were deplaned and we were provided with a spare airplane to continue our flight.uncontrollable and sudden rise of cabin temperature to extreme hot almost instantaneously without any cautions; warnings or associated ecams. This is the second time that I have experienced the exact same situation in an airbus. This is part of the reason that I didn't want to confer with maintenance while in the air; time was of the essence and task loading was very high. In my previous experience; we ended up with a dual pack overheat situation and I didn't want to end up in it again.

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Original NASA ASRS Text

Title: A319 Captain reported diverting to a nearby alternate after the cabin and cockpit temperature became uncontrollably hot.

Narrative: On our flight; during cruise and approximately 90 minutes into the flight. Both [the] First Officer and I experienced a very noticeable change in ambient noise level (mostly cabin fan circulation); we both looked at each other as if we were asking; 'what was that sudden change in noise level?' Almost immediately and without any warnings; cautions or ECAM messages; we experienced and sudden and dramatic change in cabin temperature through the entire aircraft. Cockpit registered a max temperature of 110 and the entire cabin was fast approaching 100.We did not have any noted malfunctions. I decided to turn the hot air valve off to see if that would help; but it didn't; the temperature kept on rising and getting hotter; I decided to divert. We communicated our intentions with ATC and Dispatch. ATC asked if we [needed priority handling] and we said that we just needed to do a precautionary landing and that it was not an emergency at that moment. Our Dispatcher asked if we wanted to communicate with maintenance and I declined; mainly because the extraordinary task loading that we have at the moment (coordinating with ATC; company; flight attendants and communicating with passengers).As we started making preparations for landing; we also did some amount of troubleshooting. The hot air valve being off; seem to alleviate the problem momentarily; but the hot temps returned again even with it off. We isolated air pack 1 also because it was indicating higher than normal temperatures. This seem to also alleviate the problem to a certain extend but we were still uncomfortably hot in the flight deck (98) and was about 94 in the cabin. We continue with our plan to divert and we needed to burn excess fuel to meet max landing weight. We descended to lower altitudes and extended the gear as well as started the APU and the use of spoilers to burn more fuel. ATC [was] super accommodating with delaying vectors. By the time that we were on final approach; the temperature was back to normal. We landed uneventfully and taxied to the gate. Passengers and bags were deplaned and we were provided with a spare airplane to continue our flight.Uncontrollable and sudden rise of cabin temperature to extreme hot almost instantaneously without any cautions; warnings or associated ECAMs. This is the second time that I have experienced the exact same situation in an Airbus. This is part of the reason that I didn't want to confer with Maintenance while in the air; time was of the essence and task loading was very high. In my previous experience; we ended up with a dual pack overheat situation and I didn't want to end up in it again.

Data retrieved from NASA's ASRS site 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.