A/C pressure readings?

[take a chance]

I have a 2004 ranger edge with the 3.0 in it. Can anyone tell me what the high and low pressure readings are supposed to be for the A/C system. My AC seems to be having trouble getting cold occasionally. I would blame it on the desert heat except that it is happening at night as well. I have gauges but I cant seem to locate the specs. Thamks for your help in advance

 

[Uncle Gump]

There is no set in stone spec for pressure readings... they are always dependent on ambient temperature.

 

[take a chance]

Thank you for the chart. It helps