I tried to do this and noticed the whole pipe was turning, so I just stopped.
Anyone any tips on how to loosen it off safely? Could do with a bit of A/C at the minute!
Is the system pressurised? If so, and the pipe is turning, you really need to empty the system before trying to replace, because the risk of breaking the pipe is so high. These are aluminium I think.
In your situation, I’d probably buy a replacement hose and sensor in anticipation and then get the system drained, replace the hose/sensor and then refill all done by a professional. You can either buy second hand or new. If buying second hand, make sure that the sensor comes off the pipe or has already been removed, otherwise the same thing could happen again.
Buying used hose, new sensor and taking to an AC place is probably most sensible in your situation. If hose is used you will need to buy o-rings, but they are cheap. If you must try yourself (I wouldn’t advise if the sensor is turning the pipe) wear eye protection and gloves.