I asked this question earlier but didn't really get an answer yet. I replaced an evaporator coil on a 3.5 ton carrier unit with a goodman coil, because the existing coil was rusted and leaking beyond repair. It came with a piston valve but after trying a couple different size pistons and still having high pressure, 320 psig, I switch to a txv. The pressure dropped a little bit, about 295, but I am still not able to get proper subcool temps. Also the pressure is still way high considering it's only 75 degrees, outside temp. I was only able to get 88 degrees or so on the high pressure side which means the subcool is way off. The superheat is within 15 degrees but I know with a txv subcool is what is important. Other than a restriction in the line, is there another possible cause? Of course I changed out the line drier when I installed the txv.