A/C issues...again

[bristles]

Looking at an older truck with a/c issues. Blows warm air. Had pressures checked, 38 and 250 and its 79 outside and raining. Can only manage a 10 deg drop in temp from outside to inside. This thing was built to use R12 and converted to R134. Expansion valve has been changed because pressures were 5 to 10 and 350.