I replaced the worn aircon belt, and now realise that the hesitation is caused by momentary seizing of the compressor.
I had previously listened to the compressor (with screwdriver) and there were no obvious noises.
Maybe the compressor is seizing because there is a lack of oil? (but there's probably none here anyway

Anyway, assuming it's a piston seizing, is it a realistic repair in the boondocks, or should I just go for a replacement compressor?:(
Baz