I have been working on an older carrier geothermal(10 year old) my suction pressure is running at 56psi, it is not low on refrigerant, has closed loop system and water is good, temp drop across evap. coil is 15 degree, temp rise in water is 6 degree, i tested the txv, heated the bulb and raised suct. press. to 60 psi and iced the bulb and it dropped to 50 psi, the evap coil is sweating at the top and bottom but not in the middle, I am leaning toward the coil having a restriction, but wanted to know if anything else should be checked before we go forward with coil. thanks