Air con losing cold air on acceleration

[Kellym]

Hi.
Help please. Even mechanic currently scratching heads. I have an issue where the air con cold air warms up a bit on acceleration. I drive city roads so am pretty much always accelerating. Garage regassed but no change. I originally thought the air was changing speeds on acceleration as it sounds different although I’m told I have bat hearing. Any ideas?
2015 custom if that helps

[Altransit]

All I can think of is that the belt that drives the compressor is slipping, or the comp. clutch is disengaging

[metalworker0]

or actuator flaps (if it has the motorised type) have stripped gears (very common so flopping about ) and on acceleration...is pushing air into the van and pushing flaps into hot position .

all the best.mark