I thought so at first but it did quite fine on the way back from our Mackinaw trip. Temps outside went from low 70's to high 80's from north of Milwaukee to west and I hardly noticed it till looking at the temp indicatior after my wife hooted, "HOLY CRAP, look at the outside temperature!"
I think when the cab gets hot while sitting it just takes a while to get the furniture cooled off. I stuck the thermometer in the vent and am getting right around 44 degrees there.
I have noticed that at times the a/c does not seem to blow as cold as most days. However if you use the recirculate button it keeps up with keeping cool. As a side note my truck is Tuxedo Black, I live just south of Dallas and I had my sun roof tinted which helps a lot.
I've found in recent days that taking it off auto, and using max AC helps. That keeps all air coming out of the dash vents. On auto I noticed the air is diverted to floor as well.
FYI - my other ride is a 97 MB SL500 and I use max AC this time of year - and the top is down. That little car has tons of AC, which I do divert to the foot wells.
Keeps me cool at the stop lights.
Just traded my 2005 F150 in for a 2013 FX4 with the Eco Boost.
On my 05, as with most newer f150's the air and heater cores are only separated with a small blend door. If you install a 1/2 inch ball valve in the heater hose going to the heater core and in the how eather close it, your a/c temps at the vent will drop dramatically!! I did this on my 05 and WOW what a differance.
You gotta remember many vehicles have a vacume acuated valve to do this so it causes no harm. You never have no fluid in the heater core because it's a sealed system under pressure but your not alowing HOT fluid to run through from the engine.
When you want heat again just open the valve. I'll post picks when I get a chance.
I close it in the hot summer and when temps start cooling run it open. I also open it every few weeks to move fluid.
Lots of info on f150online.com and pics.
I can say it works great and you'll have your ice cold air!