now which scenario sounds more likely a unit being off sized by 1 or 2k BTUs or that when the first txv went bad the original problem wasnt addressed. we need more info Doug. if its running like it did when the first txv went "bad" odds are what caused that condtion is probably still there. you need to call for a second opinion especially if they told you its an industry wide problem because its not. it does happen alot though when people dont practice good install habits. trust me ive already replaced over 20 txv's in warranty this year and now when one comes in the installers go back and do it the right way. as i guessed your unit does use puron. take this quote and my last one very seriously you need a technician to look at your unit not just a parts changer.