When I first got mine the charge was low, regassed and it was fine. Early this summer it wasn't working again so we regassed it but it still didn't work, no power to compressor. The explanation I was given is that if the charge gets below a certain level then the ECU isolates it. Interestingly the charge wasn't actually that low, but was outside the tolerances, just.
However resetting the ECU only worked for a week or so and the car had to go back in to have some wiring to the compressor replaced.