I bought my Fit new in 2012, and that summer to break the engine in I drove in on 900 mile journey from Florida to Texas (with a quick stop in New Orleans).

Something I have noticed about the car is that the air conditioner seems to blow well enough on short journeys but over a long one - I'm not sure I can explain it - it seems to not only not blow as cold, but it feels like the air stream is being diverted somehow (i.e. partially out of the vents in the dash when said vents are selected.) When I set the fan speed to 4, I hear it working as hard as it normally would, but the air just doesn't seem to blow out of the dash that hard.

(I figure if it was just the a/c compressor, it would still blow hard, but just not as cold.)

It did this when the car was new, and it does this now when I make a trip that lasts more than about 3 hours in duration. Has anyone else experienced this?

 

evaporator freeze-up causes this.

There are multiple possible causes, but the bottom line is it's not normal and should be fixed under warranty.

This started occurring on mine this past summer between Atlanta and Key Largo. Largo Honda replaced the pressure sensor, clutch relay, and recharged it. The trip back was fine.

Another common cause is too little refrigerant (causes compressor to work overtime resulting in gradual freezing).

Lots of threads on the subject. I think Fits are more prone to this than other cars, but it's fixable.