not exactly on topic;,i have seen a/c's in older cars having wot open setting, shuts off compressor when you floor it, was mainly for safety, dont know but your problem sounds like something like this,could you have a bad reading from a sensor or ecm?or a throttle sensor, maybe you cannt find a direct link to throttle sensor, to electronic to a/c system, ?but you may have one?? my mk3s are ahu engines, so im fully electronic, and it blows,well some,,the ahu is rather sporty
added; do you happen to have an upshift sensor?