Ac blowing at 55 degrees....

What color is the exterior of your truck? A dark color will soak up the sunlight heat more and radiate it into the cab more.

 

55 aint bad, but it needs to pee on the ground nicely. 40 would be best.

Ive had death valley at around 127 and maybe 72 inside the cab. I have no idea what ours was doing at the vent but it was nice knowing the hell outside. And this was a brand new A/C

The best kind frosts the windshield in the south after a night in the bunk. That frost might be all you have should it quit and leave you with a 140 degree oven, drying you to jerky.

 

Then you should shoot for 40 degrees at the center vents. Controls set to coldest and on recirculate.

Some questions...

When you turn the temp knob from full cold to full hot, can you hear a change in the airflow?

Is there water leaking on the passenger floorboard?

Is there a sight glass on the filter/drier?

 

Keep it on recirculate always for the coldest a/c. Blows cooler that way recirc'ing already cooled air. Not sure what it's supposed to blow out the vents temp wise. Someone told me years ago if your cab temp is 20* below outside ambient that's about as good as it gets. My a/c grenaded last week and I should get it back out of the shop tomorrow. I'll stick a thermometer in it and see what it's blowing.

 

40 degrees with a TEV...

40 below ambient with CCOT (orifice tube)

 

I was talking about the cab temp not what's blowing out the vents. They may blow 40* out the vents but they're not cooling a cab down that much.

 

It's a tad warm should be cooler.