Has anyone been seeing new TXV problems? Ive recently installed a Tempstar 5 ton 14 SEER condenser with an Aspen TXV coil. (Sorry, the Tempstar matching coil had NO WAY fo fitting in that space.) Ran fine about a month. Customer called saying it wasnt cooling and was making a ton of noise outside. I get there turned it on and watched it run perfectly and flawlessly for about 1/2 hr. Subcooling was perfect. Went to the truck to do some paperwork and customer came out and told me the noise started again. Sure enough the Internal relief valve opened up in the compressor. Shut the unit off and back on and it ran for almost 2 weeks fine again. Same problem yesterday. Gotta change out the TXV this week which is evidentially closing intermittently. Had a Trane dealer close to me tell me the same exact scenario about a week ago of a new Trane system he installed. Anyone else found this lately? Bubba
Check the mesh screen in the liquid line connection at the valve. Also, install a new liquid filter drier in the liquid line before the valve. If the valves thermal diaphram is failing, it may be a "bad" liquid charge on the thermal bulb. A failing thermal bulb will close the valve.
Thanks for the info Zyp but these are the factory installed cheap expansion valves. You know, the ones those Tiwanese or Koreans or whoever is shipping this cheap junk. No serviceable screens, parts or adjustments. The bulb charge is not bad as that would shut the valve and keep it shut. This is a very intermittent problem. It has occured twice in about a 2 to 3 week period. Im thinking there may be a lot of this showing up shortly. As always, I always install a new drier at the indoor coil. Hoping I find others that are running into this problem. I just dont want to change the valve with another valve that has the same problem. Bubba
Is it possible that the bulb is not attached correctly or if its R-22, I would also be wondering if there is some moisture in the system, or non condensibles that make it *seem* like the valve is closing.
Sorry about that. This is Strictly R-410a systems. NO R-22. Bulb is in the 10 oclock position on a horizontal run and insulated. No moisture unless the new drier and 400 microns I pulled on it and held with my JB Vac pump and digital guage lied to me. :-) Bubba
Sorry, my bad.... had to ask tho... sounds like wither a bad valve or blocked screen. Is it a heat pump?? or straight a/c?? If its a heat pump, when it does its thing, switch to heat mode to see if it clears when you go back to cooling. That might help tell you if there is trash in the line or its a bad valve. Just cause you did all the right things right when you installed it, that doesn't mean that all the right things were done right at the factory. A piece of trash in the line will ruin your day.
I just had one this week go out on an American Standard 410A system a year & a half old. I don't know what brand TXV but it was smaller than usual & it wasn't an Alco or Sporlan. They didn't put a dryer in the installation. I asked one of the Trane guys about it & he told me they don't put dryers in because they come pre-installed in the condenser.
I am kinda surprised that the condenser coil and liquid line would not hold the system charge and just pump down until the LPCO opens (if it has one), rather than driving the head up enough to open the IPR. Did you have the guages on the unit when this happened? I've never seen an IPR open on 410A yet. Where does it open? I would assume about 550- 600 more or less. I've seen them weak on 22 units and open at about 275, but these were on old units that had run with dirty condersers for years. Probably not likely to have a weak one on a new unit, but I suppose anything is possible. BTW, I agree 100% about the crappy valves they have now. A couple of years ago I got tired of them and bought a Sporlan at about $70 for a coil installation, and it was worse then the Amana valve I took off. Larry
Well, at this point Im open to ideas but I think just the opposite would be true. Remember, Im not closing the high pressure service valve and reading pressure from my gauge on the line set side of the unit (which would drop as the compressor continued to pump.) Whats happening is if the TXV is truely closing completly and I had my high side gauge on the high side service valve, the compressor would be sucking all the refrigerant pressure back to the unit via the suction line and then trying to pump it back out which it could do. BUT then it can only travel out the liquid line until it reaches the expansion valve. Thus, If I were able to catch it actually happening but before the internal relief valve opens, I would be seeing very high pressures at my high side gauge on the service valve. High enough in fact to open the internal relief valve. Make sense or did I just redesign the law of physics? :-) Bubba
All of you pathetic! what in the world noise generated in condenser had to do with expansion valve on the evaporator, if you happen to have head master valve I would say it is head master however I don't believe that there is one so? the problem is in compressor internal relief valve is must likely culprit it is relieffing pressure through when pressure get high on hot days but you are to bloody arrogant to admit.
I haven't done a lot of 410a stuff but the fact that I've already seen a bad TXV on a new unit makes me very suspicious of them. An intermittent problem is always hard to diagnose if it doesn't show up while you're there but at least you know that the compressor IR valve opened so that limits the possibilities. You could disconnect the fan & see if your high pressure switch trips instead of the compressor IR valve. If it does that would point more to the TXV, if not then the motor cutting out intermittently. I haven't had to pump down a 410 system yet but with 22 its not uncommon for the IR valve to open & not the HP switch because the head pressure doesn't get that high on a pump down. The IR valve has more of a tendency to open on longer lineset installations. Anyways I would still suspect the TXV. Sometimes an educated guess is all you can do to try & solve a problem rather than doing nothing.
Make sense(?), no. Why(?), Here we go... If in fact, you were to close the LL service valve to pump the unit down. This would eliminate the complete lineset and evaporator from the condensing unit, leaving the refrigerant to be pumped into the condenser coil. If in fact, there wasn't a long lineset (or overcharge situation), the unit would pump down just fine.
Now, since you think it's the TXV closing... This would leave you the above condition, but you're adding the LL to the condenser coil loop. Basically leaving you with a larger condenser coil. This wouldn't create a problem for the compressor, unless, the unit is excessively charged. Which shouldn't be the case, since you measured the subcooling and its fine. Unless, you added refrigerant to the system to cover another unknown problem. Did you happen to check the superheat? And since you installed this unit new, do you remember adding any refrigerant? Another thing that goes along with this, is if you limit the gas to the compressor, the head would drop off. Another factor to this equation, is that this unit has a LPS. If it was pumping down far enough, the system would shut down on LP.
As I see it, the only way for a TXV to cause the compressor to open its IRV is for it to be stuck open. Leaving you with high suction pressure and allowing excessive refrigerant flowing to the compressor. However, why isn't the HPS shutting the unit down before the IRV opens? I could only see this, if the compressor was recieving liquid refrigerant.
Do we have enough air-flow for this 5-ton unit? Does this Aspen evaporator have a hard shut-off TXV? Is there anything odd to this install?
If it was me, I would recover the refrigerant and weigh it. Evacuate the system and charge it with virgin R-410a to specifications. Just to make sure there's not a problem with non-condensibles or a refrigerant overcharge condition. I'm not second guessing your technical abilities, but I would make damn sure there wasn't something missed at the factory.
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