Penn water valve? plugged coax coil? or both?
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?
thanks for input, and questions; here's more
The water pump is new; Recent notes show EWT-66 deg / LWT-71 deg. with a pressure of 173/50 psi; That gives me an approach temp of 20 deg.
(shouldn't it be closer to 10 deg?) Temperatures measured: Liq.line 82 deg & suc.line 49 deg; thats 11 deg sub.cool & 23 deg sup.heat; TD across the evap coil was 19 deg. & cooling good; Until it reaches set point, then the HX coil stays so hot that on restart head press. soars till it trips. Initially I tried a true-off delay timer to keep pump running 10 min. to help remove heat from HX. (not enough); Only by setting for 20 min. with Penn valve wide open will it run.