The PCM should kill the AC when WOT at least that is the way it is on many other Ford vehicles.
I don't believe it does on trucks, actually I am sure it didn't on my '13. Cars yes the PCM will kill the a/c, trucks not so much, think about how many trucks spend time at near or full throttle day in and day out. That wouldn't fly with the working man.
All I know is ford said the Expy would tow 9200lbs so I purchased a lightweight that when loaded still had 2000lbs to spare. Thought I was being prudent.
Not to be a dick here but I will probably seem like one by the end of this post since you seem to be making this ford's fault for poor planning and research. The expedition is only rated to tow the difference of it's curb weight less it's maximum GCWR. The GCWR for a 2012 Expedition with the HD tow package is 15,000 lbs. So what you can tow is what your truck weighs fully loaded ready to hook up the trailer less 15,000 lbs. 9,200 lb number if for an XL 2wd with a 150 lb driver or some other crazy bottom end model.
The GCWR also derates based on altitude. So when you hit that 10,000 FT pass your GCWR has dropped 10% or 1,500 lbs (8% on the 9,000 ft pass). Now you are down to 13,500 lbs @ 10,000 ft which I am guessing you are very close to if not over.
13,500 lbs
(7,000) lbs
6,500 lbs of available truck weight.
For me my 2013 King Ranch Expedition 4x4 well optioned was just shy of 6,100 lbs. I throw myself in there at 235 lbs, my wife at 110 lbs, my kids at 38 and 48 lbs plus car seats, the hitch at 45 lbs, and misc stuff 50 lbs, I am at 6,600 lbs give or take.
When giving the tow rating it does not mean you are going to be able to maintain the posted speed limit on a 8% grade, it means you will be able to reasonably run up the grade. I would be that very few tractor trailers were passing you and likewise you were passing very few of them.
Lastly you also are limited on frontal area, are you under 60 sq feet of surface area on your trailer? It's hard to do that but I guess it is possible but most trailers are 8 or 8.5 feet wide and say 9 feet tall taking out the roof a/c and the wheels.
Here is some light reading that should have been done prior to your purchase. Attention to detail is important when you are making decisions, use this as a learning experience to gain from and hopefully grow from.
https://www.fleet.ford.com/truckbbas/topics/2012/12_FLRVTT_gde.pdf
