Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Flight Crew Total 24000
Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Illness / Injury
Flight Crew Returned To Departure Airport
Aircraft; Company Policy; Weather
Aircraft dispatched to ZZZ with inoperative APU. Heavy load factor; slow boarding process; substandard condoned air capabilities; delayed engine start with very high cabin temps contributed to a passenger having seizure climbing through approximately 10;000 ft departing ZZZ. Crew informed ATC; Dispatch and company and immediately returned to ZZZ to be met by paramedics at the gate. Inoperative APU and insufficient conditioned air capability led to uncomfortably and dangerously high cabin temps before engines could be started. Do not allow aircraft to be dispatched to typically (or known) warm weather destinations due to the risk of overheating to our passengers and crew.
A-321 Captain reported a passenger had a seizure during climb due to excessive heat in the cabin from an inoperative APU.