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  1. #14
    Join Date
    Dec 2008
    Location
    Ontario Canada
    Posts
    534
    Quote Originally Posted by curtbsa View Post
    thanks to everyone for replying. Refrigerent did not solve the problem, won't cool. Tech turned AC off and we only have the fan circulating air in the house. He said if TVX is bad, running unit will damage it. I am waiting on the company to call me back after reviewing tech notes and they are seeing if the TVX part is available in their warehouse/supply and if not, when will one come in. Told them I was concerned about either A- a leak that needs to be fixed or B - did they add too much coolant and damage the system. (don't know if its possible to add too much) They are gettting back with me later this PM.
    definately possible to add too much refrigerant!!

    Replacing the TXV will require removing the entire charge, at that point (if he is on the ball) the tech will weigh the charge removed, and get a good indication of weather or not the system was actually low or not.

    once the change-out is complete, he should be weighing the propper charge into the system, making it unlikely to leave your system overcharged.

    so at least for that much, you should be okay, as to weather or not the TXV was really the problem, only time will tell (or more information!)

  2. #15
    Join Date
    Mar 2011
    Location
    Edna Bay, Alaska Highest concentration of black bears in the US
    Posts
    623
    It looks to me that he added refrigerant to confirm his diagnosis of a bad txv. Giving him the benefit of the doubt, the pressures are not right for 410a. The temp split is definitely not right. Again, giving him the benefit of the doubt, I think he's right.

  3. #16
    Join Date
    Mar 2007
    Location
    Myrtle Beach, SC
    Posts
    2,919
    Quote Originally Posted by LKJoel View Post
    definately possible to add too much refrigerant!!

    Replacing the TXV will require removing the entire charge, at that point (if he is on the ball) the tech will weigh the charge removed, and get a good indication of weather or not the system was actually low or not.

    once the change-out is complete, he should be weighing the propper charge into the system, making it unlikely to leave your system overcharged.

    so at least for that much, you should be okay, as to weather or not the TXV was really the problem, only time will tell (or more information!)
    I would not remove the refrigerant. Pump it into the outdoor unit, change the TXV, install a new drier, vacuum the system, open service valves. Start the system and check the charge. Still sounds like a leak. Pressures way low for R-410a.
    Last edited by Kevin O'Neill; 04-27-2011 at 03:17 PM. Reason: spelling
    Remember, Air Conditioning begins with AIR.

  4. #17
    Join Date
    Dec 2008
    Location
    Ontario Canada
    Posts
    534
    Quote Originally Posted by Kevin O'Neill View Post
    I would not remove the refrigerant. Pump it into the outdoor unit, change the TXV, install a new drier, vacuum the system, open service valves. Start the system and check the charge. Still sounds like a leak. Pressures way low for R-410a.
    Running under the assumption that the TXV has failed and is stuck shut, it will be very difficult to pump the refrigerant back into the compressor.

    Besides, the tech didn’t know how much was in there to start with, then he added a bunch, he is not sure if there was a leak or not, there is a big question mark as to whether or not the unit is properly charged, removing it and re-charging it is the only sure way to know that the unit has the correct charge when you leave, a little more work for a lot more piece of mind.

    That’s just my opinion though, some times i go a little overboard

  5. #18
    Join Date
    Mar 2007
    Location
    Myrtle Beach, SC
    Posts
    2,919
    Back when I lived in PA, we always knew the length of lines. Weigh-in was best. Now the lines run through the walls, often strange routing from outdoor unit to air handler in the attic. Often we have to add a pound over what the charts say. It all depends on local conditions. The TXV is flowing some, but yes, it may be difficult to pump down. I wonder if the tech wrote the pressures down right.
    Remember, Air Conditioning begins with AIR.

  6. #19

    cooling now

    I really appreciate all the replies. A new tech came out. Said first tech had added refrigerant to do diagnostics. He replaced HVX, emptied system and refilled. Said should be good to go. Did not give me new pressure readings though. Seems to be cooling now. I'll be back if any more problems. Thanks again.

  7. #20

    Talking sorry, meant TXV.

    sorry, meant replaced TXV. Dealing with too many anacronyms today.

  8. #21
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,292
    For those of us techs who have had a TXV fail on us, but our initial reaction was to think the system was low on charge, I will maintain that your initial tech was correct on the TXV failure (as evidenced by the new tech replacing it and you have cooling again). The thing I have to remind myself as a tech is that my first response when I find a system with what appears to be a low charge, don't add any refrigerant until any other factor that can contribute to the same symptoms has been found and eliminated. Just the other day I had a rooftop unit that indeed was low on charge. I started to add gas but stopped myself. Partly because my eyes zoomed right in on where the leak was. I could see it even without breaking out leak detector. Partly because even if the leak had not been that obvious, it was foolish for me to keep adding gas to a system with no other factors causing it to indicate a low charge but a low charge itself, which can only be due to a leak.

    Old habits are hard to break. Knee jerk reactions in service aren't always the best.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  9. #22
    Join Date
    Dec 2005
    Location
    Cincinnati, Oh
    Posts
    4,923
    Glad to hear they've got it working.

    I agree with shophound. Sounds like he figured on bad txv, which it was. I've had txv's bad out of the box, and I've had txv's go bad after a week.

    Kevin, I'm not arguing, but:
    IF you thought there was the possibility of a loss of charge, why would you pump a unit back into itself? Your not worried about sucking moisture in, especially with a possible malfunctioning txv?
    "Better tell the sandman to stay away, because we're gonna be workin on this one all night."

    "Dude, you need more than 2 wires to a condenser to run a 2 stage heatpump."

    "Just get it done son."

    Dad adjusted

  10. #23
    Join Date
    Jul 2006
    Location
    Virginia
    Posts
    4,608
    if a system is properly charged on start up and then the txv fails you have high sub cool and high superheat if he added refrigerant to get the proper sub cool then either the unit was not charged correctly on start up or the refrigerant leaked out.if the tech that replaced the txv followed proper procedures then the system should leak free

  11. #24
    Join Date
    Feb 2010
    Location
    In a boiler room
    Posts
    7,049
    Quote Originally Posted by hvacvegas View Post
    Glad to hear they've got it working.

    I agree with shophound. Sounds like he figured on bad txv, which it was. I've had txv's bad out of the box, and I've had txv's go bad after a week.

    Kevin, I'm not arguing, but:
    IF you thought there was the possibility of a loss of charge, why would you pump a unit back into itself? Your not worried about sucking moisture in, especially with a possible malfunctioning txv?
    If you don't let it pump down into a vacuum you can't suck any moisture into it. I usually just get it down to 5 psi and shut it off.

  12. #25
    Join Date
    Mar 2011
    Location
    Galveston Texas
    Posts
    530
    In all reality your not suppose to pump a scroll compressor into a vacum state anyway

  13. #26
    Join Date
    Dec 2002
    Location
    SouthEast NC ICW & Piedmont Foothills
    Posts
    7,635
    Quote Originally Posted by curtbsa View Post
    A new tech came out. Said first tech had added refrigerant to do diagnostics. He replaced TXV, emptied system and refilled. Said should be good to go. Did not give me new pressure readings though.that doesn't say much for the "tech" Seems to be cooling now. I'll be back if any more problems. Thanks again.
    you should ask his boss for those numbers

    saying it is charged correctly and not documenting it is the same as a lie in my book
    It`s better to be silent and thought the fool; than speak and remove all doubt.

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