Just a quick back-of-envelope sum. Let's say we are doing 350 mph as you say, and has an intake diameter of 3 metres.
A 3 metre diameter implies a cross-section of about 7mē. 350 mph equates to 156 m/s.
So, 7 x 156 = 1095 m^3/s of air.
Standard sea-level air density is 1.225kg/m^3.
So, 1095 x 1.225 = 1342kg.
Which is 1 1/3 metric tonnes per second.
So, by back of envelope guesstimation, a tonne a second seems about right.
With regard to your AC, does it imply the mass of air that it can keep "conditioned"?. 4 tonnes would be 3,265 m^3, or about 35,000 cubic feet. That would equate to an air mass of something around 44ft x 44ft x 18ft - which I'd guess is probably the size of the air mass in a typical modern american house.
G