Ford F350 AC Lack of power

Hi. I hope someone could be of some help as I need it badly. I drive a Ford F350 (Armoured) and work for a security company in Iraq, we transport members of the US Department of Justice and interpreters for the US Army. The AC of the vehicle that I am driving has been giving problems for that past month. Currently we are having tempretures of about 120 farenheit. Having local nationals (iraqies) as vehicle maintanance guys does not help a lot as they are not able to solve the problem.

The problem with the AC is that it is working but the it just does not have any power, it makes cold but comparing it to the ohter Ford's we have it as good as putting their setting on the max ac setting number 1. That is just to compare how cold mine is making and how hard it is blowing to the other vehicles. Does anyone have a sullution on how to fix this by myself? Getting spares and a good dealership is just about impossible.

Thanks guys.