I have a 5ton server room AC with glycol drycooler that has been cutting out on high head pressure; If I open the Penn valve wide open & run the drycooler pump continuously the ac works fine. When running like this the head pressure is about 150 psi (R-22). It has a tube in tube coax condenser coil which measures a TD of just 3-5 degrees between inlet & outlet water temp (is it plugged-up?). If I try adjusting the head pressure control for higher opening pressure I get no change until near the end of travel. Then my head pressure rockets up toward cut-out (375psi), the coil temperature also rockets up & it trips out before I can back it off ( faulty water valve?). So... Faulty valve? Plugged coil? Both? Any advice?