A/C blows warm when standing still, fine on the road.

Maybe if you can post a video of the system running, so we can hear the sounds is making and all that. Check if the radiator fan turns on when you turn on the A/C, it should turn on in most of cases, specially if it's hot outside.

 

Yes, the basic symptom sounds like the radiator fan may not be running.......or there is some air blockage up there.
The growling sound likely is a WHOLE different matter.

 

Guessing there’s two fans behind radiator? Watch them, with the hood up and AC running. If it’s like most systems, both fans should come on, same time as AC compressor.

growling sound could be AC compressor; any recent AC top up? Dealership or? Speculating recharge with wrong oil.

paging @lech auto air conditionin