I have a 2009 Ranger Sport with the bigger v6. The AC only works when it is on max. The rest of the settings only blow heat even when the temp **** is all the way in the blue.
I tried to recharge the AC with a do it yourself can but the gauge read that the charge was normal when I plugged it in.
Now I'm just scratching my head.
Any suggestions ?

 

Open the hood and start the engine, AC OFF.
Locate the AC compressor, should be drivers side front of the engine, below power steering reservoir, with fan belt on it.

Turn on the AC to low, compressor should "click" on.
And stay on.
If not then most likely cause is one of the two pressure sensors has failed or there is a pressure problem, but I wouldn't think the MAX AC would blow cold in that case.

The more common problem on Rangers is the Blend Door, and Explorers, they both use the same setup.
Difference between regular AC and MAX AC is the fresh air door, when MAX AC is selected the fresh air door is closed and the already cooler air in the cab is recirculated.
There is also no temp control in MAX AC, cold is it, lol.
And if you have no temp control on regular AC then that is also a Blend door issue

Google: ford ranger blend door actuator

Lots of info and videos on testing and fixing this common problem
The model years are all pretty much the same setup up to 2012