Originally Posted by
Frosty_VA
Hi folks! Been reading forum for 2 years, now I really need your help. I'm working on walk-in cooler, Hussman, R-22, 2 evaporators, single condensing unit. CU has receiver and headmaster, no fan cycle controls. First I got a call 'both evaps iced up'. So I removed/thawed ice, unit low on charge. Pressure tested w/ nitrogen to about 350-370psi, found VERY small leak right at receiver inlet at nut. Tightened nut, looks like leak is gone. Pulled deep stable vacuum(440psi) with LL solenoid open, charged unit with 8.5lbs of refrigerant(sight glass clear, added juuust a bit over for winter charge). What's weird is that right at compressor outlet pressure is over 360, but at LL past filter, solenoid and sight glass is about 220. So I checked if filter-dryer plugged - no, no temp drop across, no temp drop across solenoid either. Headmaster works, opens/bypasses below 180 like it should. So I decided to double check incondensibles, pulled deep vac again, all valves open, charged with 8 lbs of R22 again. Now discharge pressure 230, pressure at LL 170!, suction 20 psi, sight glass clear. WTH? Why there is ressure difference of 50-60 psi across condenser coil? Restriction at condenser? I also checked amps at compressor - 5.5A, they're lower than exact same neighbour unit has - 8.5. 3ph unit, proper voltage, no difference between legs. Superheat at TXV with 20psi is about 55 degrees. Could I damage TXV while pressure testing with nitrogen?
Any ideas?