I had a nasty experience last year.

I was to replace a small hermetic compressor at a general store. It was a saturday with the place full of customers.

The high side of the compressor was soldered in place and it was a capilary tube system. The new compressor had different conections so i decided to desolder the high side pipe from the condenser and make a new pipe from the condenser to the compressor. The pipe from the condenser was routed vertically from the condenser and there was the joint i planned to desolder. I recovered the refrigerant from the only conection at the low side of the system. I didnt get out as much refrigerant as i believed should be in the system. However i didnt linger more about it. As the event was to unfold that showed to be a disastrous failure.

I'm sure some of you already are able to foresee what nex happened.

I started to unsolder the vertical joint. Suddnely there was a powerful whoomm as the joint came apart and the refrigerant and oil bursted out up in the air. This happened instantly and the gas torch was of course still aimed at the joint with the result that the oil imidiately caught fire and transformed to a 3 metre high flamethrower which barely avoided my head.

There was nothing i could do other than wait as the flames died out after some 5 second. But then the store was filled with nasty sticking smelling toxic white smoke and the 20 or so coustomers was shocked.

The moral of this little mishap is to never ever desolder any joint before you have physicaly verified the absence of refrigerant under pressure in the pipe.

This is especially valid in the instance that you unsolder a pipe between a compressor and a totally clogged cappilary tube with a condencer full of refrigerant and oil in between.