I have a 2012 f250. It's a king ranch. The a/c compressor doesn't turn on. Where do I start. Low freon? Or a sensor? Anything I can figure out using forscan? Thanks

 

I'd definitely start by checking your pressures. At least the low side but much better if you can check both.

 

If the compressor isn't running, both the high and the low sides will be identical at the static pressure.

Yes, check the static pressure. If the charge is too low and the rest of the system is working properly, the compressor will not be activated.

 

I'm thinking the evap sensor is bad. It's not ohming out.

 

What should the pressures be with the pump off? There about 3-4 on both sides.

 

System static pressure is determined by temperature. See R134a column at https://highperformancehvac.com/hvac...erature-chart/ for example.

I don't know what "3-4 on both sides" means. "3-4" WHAT? You need to use units or more details to communicate what you are observing.

 

There both reading 3-4 psi on gauges. Compressor not kicking in at all.

 

As already noted, it's essentially empty with only a tiny residual amount of charge.