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Sticking TXV

charliechicago
charliechicago Member Posts: 134
in A-C, Heat Pumps & Refrigeration

Hello All

I was working on a unit that was not working. The head pressure got really high and then up and down a little and then really high again and then the breaker tripped. I replaced the TXV and it worked well for a week and then same think. When I originally changed the TXV I smelled a sweet smell from the unit in the attic. The history of the unit is that it was installed the end of 2022 (not by me) and in 2023 they had to add freon. I'm wondering if they added a leak sealant that's gumming the TXV. Is there anything on the market that I can add to the system to counteract a leak sealant?

Thank you, Michael.

Comments

  • Jamie Hall
    Jamie Hall Member Posts: 24,696

    Probably not…

    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
    SuperTech
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,364

    There were issues with TXVs sticking a few years back I think it had something to do with the oil. Maybe they did a bad evacuation and had moisture in the system but then it would have been fixed when you changed the valve.

    AC Service tech on You Tube has good videos

    Maybe recover leak test and recharge. Take the old valve apart and see what you find.

  • Ironman
    Ironman Member Posts: 7,537

    This has worked well for me when that was an issue about 10 years ago.


    IMG_2167.jpeg

    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • EBEBRATT-Ed
    EBEBRATT-Ed Member Posts: 16,364

    @Ironman

    Do you know what caused the sticking? As I recall it had something to do with the oil but I could be wrong.

  • ratio
    ratio Member Posts: 3,777

    IIRC there was an unvalidated change to the mfgr's rust inhibitor that caused it to gum up after some time in the field. Again, IIRC, at least Trane's factory-blessed solution was a can of AC Renew as @Ironman shows above.

    Ironman
  • ChrisJ
    ChrisJ Member Posts: 16,260
    edited June 3

    I thought the rust inhibitor issues were long long long before 2022?

    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
    pecmsg
  • Ironman
    Ironman Member Posts: 7,537
    https://forum.heatinghelp.com/discussion/comment/1803052#Comment_1803052

    Something done in the manufacturing process. I’ve heard a couple of different explanations.

    See @ratio post.

    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • Ironman
    Ironman Member Posts: 7,537

    Allow me to add my two cents worth right here: leak sealants are junk technology. They all seal based upon a chemical reaction when refrigerant, oil and air combine. If a system has a low side leak and it’s run in a vacuum, then you have a scenario where all three have combined IN the system and the sealing process will occur IN the system, not just at the point of leakage. The same will apply to a system that’s been opened after the sealant has been added like what the OP has described.

    In spite of what the sealant manufacturer claims, it can cause clogging or sticking within the system.

    There’s no such thing as a mechanic in a can!

    If a system is low on refrigerant, do the job right! Locate the leak(s), repair them properly according to industry standards and manufacturers instructions, change the drier, evacuate and charge the system.

    Fix-a-Flat belongs in tires, not refrigeration systems.

    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
    EBEBRATT-EdSuperTech
  • ChrisJ
    ChrisJ Member Posts: 16,260
    https://forum.heatinghelp.com/discussion/comment/1803094#Comment_1803094

    Do any modern systems actually run in a vacuum even if low?

    I'm asking because with methyl formate and even SO2 it's a common issue, but I was under the impression that never happens with modern systems and they are always positive pressure.

    Your comment makes me think I'm mistaken.

    I agree, leak sealants are bad bad things.

    Single pipe quasi-vapor system. Typical operating pressure 0.14 - 0.43 oz. EcoSteam ES-20 Advanced Control for Residential Steam boilers. Rectorseal Steamaster water treatment
  • Ironman
    Ironman Member Posts: 7,537
    https://forum.heatinghelp.com/discussion/comment/1803097#Comment_1803097

    I was referring to a system running in a vacuum if it was low or out of refrigerant and it had a low side leak.

    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.

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