A hunting TXV oscillates the evaporator between overfeeding and starving instead of settling on a stable superheat, and the fix depends entirely on which of several distinct causes is behind it \u2014 most of which have nothing wrong with the valve itself. This article gives you the readings that confirm hunting rather than a genuinely unstable load, the checklist of causes in the order worth working through, and the tests that confirm a valve is actually faulty before you replace a part that was never the problem.<\/p>\n\n\n\n
A stable TXV holds superheat within about \u00b11 K of target once the system has settled, with slow, small drift as ambient or load shifts gradually over minutes. A hunting valve instead shows a repeating swing of 3\u20136 K or more above and below target, cycling every 30 to 90 seconds, sometimes faster. Suction pressure oscillates in step with it \u2014 you’ll see the low-side gauge needle visibly moving up and down rather than sitting steady, often by 50\u2013150 kPa through each cycle. If you watch superheat swing from 2 K to 9 K and back to 2 K within two minutes, repeatedly, that is hunting, not a load change.<\/p>\n\n\n\n
A single snapshot reading can land anywhere in the swing and look like a normal, in-range superheat by coincidence. Log suction line temperature and suction pressure at 15\u201330 second intervals for at least 5 minutes before you draw a conclusion:<\/p>\n\n\n\n