2006 F-250 Lariat

[ambulance doctor]

The Chief has a 2006 F-250 6.0 Lariat with the auto control HVAC system. The truck AC doesn't work very well setting still. It cools better at highway speeds. Obviously there is an airflow problem.
The pressures on both high and low sides are high with the truck setting in the shop. The outside temps lately here have been around 100F with 90% humdiity. The condensor is clean and I can shine a flashlight through the codensor anywhere. I double checked the factory charge and it is correct. The truck does have a tube style grille in it. I can put a shop fan in front of the truck setting and it helps.
My question is: Is the engine fan controlled through the PCM by a high pressure switch? Is there, perhaps, a software upgrade I can have done at the dealer? Any other ideas?

[ambulance doctor]

Consequently, I have a 05 E-450 ambulance doing teh same thing with regular HVAC controls.

[tbisme]

Check the hose going to the heater control valve, and the updated TSB said 45-47oz of freon in the system. but i cant remember..... I do kn ow that mine was low and did the same ting after they pulled my cab, they said they put in the correct amount, and i added 12oz to it and it will now get so cold at idle it will give you a headache, and that is how it did from the factory, before they removed the cab.