An Aeromexico Boeing 787-8, performing flight from London Heathrow (UK) to Mexico City (Mexico) with 237 people on board, reported air conditioning problem.

• Aircraft was climbing out of London when the crew stopped the climb at FL260 but continued in the general direction of Mexico City.
• About 35nm southeast of Isle of Man (UK) the crew decided to return to London, declared PAN and descended the aircraft to FL200 reporting a cabin air compressor failure disallowed them to cross the Atlantic, they were going to perform an overweight landing at London.
• The aircraft landed safely back on London’s runway 27R about 50 minutes after the decision to return.