synopsis R-404a system running high liquid line pressure 310 to 320 psi, no load onfreezer, 0*F case temp. 80*F ambient air in room, 28psi suction 10*F superheat full colum of liquid in sight glass slowly charged till glass cleared, it's 11:30 i may have forfgot other info I'm tired now!! haha
Let me start off with this, the model is a TUC-48f little 2 door undecounter thingy. This Freeser has had a "troubled history" lots of service calls over the past 6 years of operation. I looked back through the records of all the service done on the machine, this customer actually had good records!
Most of the service on the machine had to do with blocked condenser and/or blocked air flow to condenser. I think we can all agree that that situation is hell for these little systems with the newer refrigerants and POE.
Over a year ago or maybe better on two the system had a blocked cap tube so it was opened and cleared by blowing nitrogen through it. It worked dandy for 7 months, then same problems re-occured. I assume it was the same tech but this time the cap tube had been replaced(and it was obvious) system worked again for almost a year again.
System running in a vacuum on low side so i preformed a prwessure test on nitrogen and system held 250psi for over 2 days with out budging, no leak right? (Itwas during that time i looked in to the history on freezer)
After having a grand old chat with one of the techs at true basically comming to the conclusion that with the history we probably had a contaminated system from the POE oil breaking down under the high heat situations and thus blocking the little bastard um i mean cap tube!
I was in the mood to experiment with this little freezer so i decided that I would get rid of that little cap tube and install a TXV and reciever, so I did. the idea sounded fun but once i got nto it i was reminded how i hate working on little reachi-ins who really like sharp sheet metal cuts anyway haha!
So now I have the freezer running and there is excessive head pressure 310-320psi on the liquid line, suction is 28ish psi and superheat is around 8*F
case temp is is steady at -5*F to 0*F
system is still running on the temperature control but i was thinking of throwing on a pressure control in there to cycle it.
any ideas on what to look for?