These articles don't say why, but they identify the problem. Other articles I have seen say that HVAC compressor explosions are very rare because there are many design safeguards. As an extension of the Made in China experiences, perhaps the increase in 2nd and 3rd world manufacturing is lowering/sidestepping the design and manufacturing standards for HVAC compressors. That's my guess.
Originally Posted by 2016 American Academy of Forensic Sciences
Title: Deaths Due to Accidental Air Conditioner Compressor Explosion - A Case Series
Abstract: In an air-conditioning system, the compressor is a large electric pump that pressurizes the refrigerant gas as part of the process of turning it back into a liquid. The explosion of an air conditioner (AC) compressor is an uncommon event, and immediate death resulted from the blast effect is not reported in forensic literature. We report three such cases in which young AC mechanics were killed on the spot due to compressor blast, while repairing the domestic split AC unit. The autopsy findings, the circumstances leading to the explosion of the compressor, are discussed in this study.
Keywords: accidental death; air conditioner; compressor blast; forensic pathology; forensic science; mechanic.
Originally Posted by Vehicle Air-conditioning Specialists of Australasia
Mysterious spate of deadly AC explosions
Published 14 June 2015
Numerous technicians in Bangladesh, Cambodia, India, Spain and Vietnam have been killed or injured in recent weeks in a spate mysterious air conditioning explosions, according to sketchy, often contradictory media reports from those countries.
Burning question
In the Bangladeshi capital Dhaka, four or five workers were taken to hospital for treatment of burns ranging from seven to 30 per cent of their bodies after an air conditioner was said to have exploded.
Just weeks later a technician died in the same city after suffering burns to 80 per cent of his body from an air conditioner gas cylinder explosion in an air conditioning workshop and another was seriously burnt.
At a casino in Cambodian capital Phnom Penh, one technician died at the scene and another on the way to hospital when an air conditioner they were working on exploded in what local police described as “like a grenade” and shattered all nearby windows.
In the city of Dehradun, around 250km north of the Indian capital Delhi, a technician died and three others were injured in another air conditioning explosion as they were replacing a compressor. At least one of those hurt was reportedly seriously burnt.
A technician working on a rooftop air conditioning unit in the Spanish city of Seville suffered burns and injuries caused by flying components after the equipment exploded, while a pedestrian in the street below is also thought to have been hurt by falling debris.
Reports of another death and two serious injuries have also emanated from a suburb of Vietnam’s largest city, Ho Chi Minh, where an explosion ripped through an air conditioning repair shop.
There are no suggestions that these incidents are related and all remain under investigation, but at least two have been blamed on incorrect working procedures and another attributed to a leaking cylinder of brazing gas.