Hello reddit peoples I've got a bit of a head scratcher of an issue with a walk-in cooler. Initially it had a TXV that was a ball of ice. Supe wanted it changed. We changed it. Unit seemed to be running OK. However over the past month or so the walk-in has been running progressively warmer. A co-worker found dye all over the compressor and it seemed fresh so he wanted to isolate the compressor and pressure test it with nitrogen. He could not however pump the system down. With the outlet of the receiver closed the low side pressure never got below 66psig. It got diagnosed to a failing compressor or Reed valves that weren't seating properly. Tonight we put a new compressor in and the unit is doing the same thing. Low side pressure won't go below 66psig and high side pressure wasn't going above 150psig. My co-worker wanted to adjust the txv in like a pressure regulator to flash more refrigerant off out of the txv(how he described it) but when he did that head pressure came down to 129psig(rose to 137psig) and low side came down to 60psig. Our systems have low ambient control valves that as I understand it are trying to keep head pressure up at a certain point by flooding the condenser. With that being the case I would expect to see higher pressures on the high side. Has anyone out there run in to any issues like this where a system with a low ambient control valve is running low head pressure and also higher suction pressure that never pumps down. For reference the above pressure are with a 38-40 degree outside ambient and a box temp of 44 degrees. Thank you for any insight and sorry for the long post!
Edit: the suction line was icing up and also the low side of the compressor head was starting to ice. 20 min after txv adjustment low side pressure was 60 psig and high side was 140psig
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