Car is a 99' A6 2.8 Q with only 25K miles. The A/C, every now and then, would blow warmer than expected cold air; one time going through a car wash I put trans in "N" neutral and the air temp went totally warm as if A/C is not running at all. In all these cases if I put the recirculation on the temp returns to cold almost immediately.
I don't think this is a refrigerant issue but maybe an air gate or (less probable) belt issue.
Any help here is welcome