A/C not cooling when moving

My A/C works perfectly when I’m parked. Even at 49c. When I start moving it starts getting warmer. The compressor is still running but the air is little bit warm. It’s acceptable when I’m driving until 50 kmh when I’m driving faster than this it becomes warm and humid. I disabled the ventilation door and there is no air coming from outside the car. I checked if there is a leaking but there was not. And the Freon level was okay.
Please advise.