If the output temp is below 32o the evaporator will ice up. especially if it is humid.

 

None of the usual symptoms of evaporator icing were described. Those events usually manifest as fog or very humid air out the registers along with reduced/no airflow through the system while the blower continues to spin.

The symptom to focus on, IMHO, was the sudden shut-off of the blower and what could cause that. An iced evaporator won't cause that fault. An intermittent fault in the FCIM or any of its inputs, including power and ground, would be most likely.

That the dealer determined the charge was "5% low" suggests either a small leak, factory under-fill, or a recovery machine scale that's a bit out of calibration. In any event, an accurate charge will be a good thing and would make future diagnosis more likely to succeed. It's just not going to solve the intermittent shutdown and restart issue. I'd wager a 6-pack that they'll return the truck with a "no fault found" regarding the shut-down unless they happen to get lucky and it happens to the tech while he's working on the system.

 

Just to bring an end, but no real answer: at follow up service no leak was found, mechanic drove the truck for 21mi and reported air conditioning working as expected. Weird but I think consensus that system was low on refrigerant and freezing was probably correct.

 

I recommend filing a safety complaint with the NHTSA at https://www.nhtsa.gov/report-a-safety-problem#index. They are on charge of investigating safety complaints and issuing safety recalls. If enough owners complain, the NHTSA is more likely to issue a recall and force Ford to fix this. The real safety issue isn't the temp control, although that is a huge inconvenience. The safety issue is that while the blower is malfunctioning, it cannot defog/defrost the windshield. I have had same issue with the AC and blower over last 14 months. 2 different dealerships and 4 visits totalling going on 4 weeks in the service department. Bottom line, service department cannot find error code and cannot duplicate so they will not fix. Likewise I called Ford corporate customer service, and they will not help without an error code or the problem duplicating in the service department. There is a TSB out by Ford 22-2089 for limited Vin numbers, so Ford is aware this is an issue and yet they still will not fix it. Everyone please file complaints to the NHTSA to force Ford into action.

 

I suggest you get (if you don't have) a thermometer and check the a/c output temp. then you will know where you stand.