I've had this truck just short of a year and don't have to drive it much.

I've found that the AC compressor does not engage until the vehicle reaches full operational temperature (temp needle in the middle). Once it comes on, the AC is plenty cold. If I turn off and on the AC via HVAC controls, it kicks right back on. If i turn the truck off and start it right away it will come on. If i shut the truck off and the engine cools a bit, the compressor does not engage again until the vehicle returns to full operation temperature.

Where should I be looking

 

I would invest $15 in an OBD2 Bluetooth reader, ELM327 is one model

Reason being is you have a very unusual symptom

These OBD2 readers work on ANY 1996 and up vehicle, not a Ford or Ranger tool, ANY vehicle, its the LAW

AC compressor is controlled by the engine computer
There are a few sensors on the engine that will turn off the compressor
You need to use the OBD2 reader to see what those sensors are "telling" the computer
ECT sensor temp
Throttle position


Other problem could be faulty pressure switch on AC lines, needs to be warmed up in engine bay by running engine