I have the zone a/c. When driving down the road after a while it will start to blow harder for a few minutes then return back to normal. It has done this when both side temps are set the same and also when at max a/c but lower speed. Is this normal?

 

Yes, automatic climate controls will vary fan speeds

IMO Max A/C is only to be used when you want max A/C. It goes with "Lo" setting and not a temp setting, max should be max, you want it all

I might not be understanding your question though, I virtually never use max ac and if I do, it's for a short amount of time as it's just not needed (I only live in Atlanta though, not like south TX or something, and I have tinted windows and use a sun visor when parked in the summer for the windshield). Are you just driving around with it on max?

 

No I don’t usually run my air on max. I was in Georgia recently at it was HOT that’s what made me put it in max. I have had the air blow harder when it’s not on max but set at a temp like 70, been driving for about 30 mins, the cab is cool and all of a sudden the air starts blowing harder for about a couple of minutes. Noticed this on longer trips also. Doesn’t matter if hot or cooler out side it still does that. I thought maybe it has something to do with humidity in the cabin.

 

My 13 has done this on several occasions. Usually happens on a very hot day when the truck is heat soaked. I can be leaving my sons house and after running for say 2 minutes, it will temporarily quickly ramp up and back down. Checked for loose or damaged connections, none found. Wrote it off to another Ford innovation for CAFE standards.

 

Both my 15 and now my 2020 do this. When you hear it blowing harder, the air actually seems to come out colder, more forcibly, but when you don't hear it pushing out as hard, it doesn't seem to be colder. I can't put my hand on it, completely random. I used to turn it on and off on my 15 to get that boost to turn on, but my 20, I can't seem to get it to do it, just totally random.