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  1. #40
    Join Date
    May 2014
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    Bay Area California
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    Keep in mind that every heat pump has two metering devices and two check valves. The check valves may be separate, built into the orifice, or built into the expansion valve. But they are there.

    https://hvac-talk.com/vbb/showthread...eversing-Valve

    Above is a link to something I tried a few years ago when changing a reversing valve, and it made that job go real smooth. Just got to have some real good strong grip strength and a sharp pair of tin snips.

    Another trick is if the reversing valve is difficult to get to, just remove the condenser. That's a lot easier than many realize. Lastly, of course, is keeping the valve cool when brazing it in. Wrap well with a wet cloth, do one pipe at a time, letting the valve cool between each braze joint, and they're not that big of a deal.

    Taking your time and thinking about what you are doing will typically take less time than if you try to rush it.


    Quote Originally Posted by Achso017 View Post
    If I had pressure on the discharge port (what would be the suction port in cooling) than I would say there is a restriction inside the air handler. Strainer, metering device, etc. But I had dripping pressure equal to the dropping pressure on the other ports. All three were pumping down. Nothing was getting past the reversing valve. There is literally a six inch stub of pipe between the RV and the discharge port. No check valves, no strainers, no driers, no crimps, nothing. The compressor has a muffler and the reversing valve. That’s it. If it was the muffler than I would have no pressure I either heat or cool. By process of elimination it has to be the RV. I was desperately searching for any other cause as I really did not want to have to change that valve.
    I do a triple evac with nitro to remove non condensables.

  2. #41
    Join Date
    Dec 2010
    Location
    WV
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    325
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    Quote Originally Posted by BBeerme View Post
    Keep in mind that every heat pump has two metering devices and two check valves. The check valves may be separate, built into the orifice, or built into the expansion valve. But they are there.

    https://hvac-talk.com/vbb/showthread...eversing-Valve

    Above is a link to something I tried a few years ago when changing a reversing valve, and it made that job go real smooth. Just got to have some real good strong grip strength and a sharp pair of tin snips.

    Another trick is if the reversing valve is difficult to get to, just remove the condenser. That's a lot easier than many realize. Lastly, of course, is keeping the valve cool when brazing it in. Wrap well with a wet cloth, do one pipe at a time, letting the valve cool between each braze joint, and they're not that big of a deal.

    Taking your time and thinking about what you are doing will typically take less time than if you try to rush it.
    That’s awesome. I thought I was the only one to do it like that. Very happy to read that, thank you.


    Sent from my iPhone using Tapatalk

  3. #42
    Join Date
    May 2018
    Location
    Central Florida
    Posts
    203
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    Yeah, sucky days come with the trade for sure. I am really hard on myself when I misdiagnose, but I guess there’s nothing like learning the hard way.

    On the system mentioned in the OP with the reversing valve... is it a recip compressor? Cause the symptoms sound eerily similar to a compressor we had a while back with reed valves not seating properly.... low liquid pressure with low subcool..... high suction pressure with low superheat.... crummy split across the evap. It confused me for a couple days.

    I came very close to swapping the TXV but someone on this forum suggested bad compressor.

    Dunno, might be worth looking at.

    As for how to find stuff at the same time.... I have not used it as much as I want, but I got an infrared camera a while back. It’s not useful everywhere but is really great at stuff like watching a reversing valve to make sure it’s seating, checking for condenser coil restrictions, visually seeing how full of liquid an evap coil is, verifying bleed by in compressor valves, etc. it’s definitely a game changer on certain types of jobs.... like the one you’re posting about!

  4. #43
    Join Date
    Aug 2018
    Location
    Piedmont Triad, NC
    Posts
    694
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    Thread Starter
    Quote Originally Posted by 3.14 View Post

    On the system mentioned in the OP with the reversing valve... is it a recip compressor?
    It’s a scroll 🙁. I also like the FLIR for certain things. Including this RV. That’s one of the ways that convinced me it was not seating properly.

  5. #44
    Join Date
    Aug 2018
    Location
    Piedmont Triad, NC
    Posts
    694
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    Thread Starter
    Quote Originally Posted by BBeerme View Post
    Keep in mind that every heat pump has two metering devices and two check valves. The check valves may be separate, built into the orifice, or built into the expansion valve. But they are there.

    https://hvac-talk.com/vbb/showthread...eversing-Valve

    Above is a link to something I tried a few years ago when changing a reversing valve, and it made that job go real smooth. Just got to have some real good strong grip strength and a sharp pair of tin snips.

    Another trick is if the reversing valve is difficult to get to, just remove the condenser. That's a lot easier than many realize. Lastly, of course, is keeping the valve cool when brazing it in. Wrap well with a wet cloth, do one pipe at a time, letting the valve cool between each braze joint, and they're not that big of a deal.

    Taking your time and thinking about what you are doing will typically take less time than if you try to rush it.
    Good info. Thanks. I hadn’t thought to use snips. Maybe some bolt cutters if there is room. I saw the tip about removing the coil about a year ago on YouTube and smacked my forehead for not thinking of it myself. That’s what I did this time and it was a hell of a lot easier. All that practice stripping down old units for copper really came in handy 😁

  6. #45
    Join Date
    Sep 2002
    Location
    Virginia
    Posts
    6,770
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    Quote Originally Posted by Achso017 View Post
    I forgot to cycle the valve when I was recovering so I got a face full of 22 when I unsweated the discharge line from the valve
    Ive read other guys CUT the old TXV out ….

  7. #46
    Join Date
    Aug 2018
    Location
    Piedmont Triad, NC
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    694
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    Thread Starter
    Quote Originally Posted by Snapperhead View Post
    Ive read other guys CUT the old TXV out ….
    Lol. Would’ve been the same result. *cut* *cut*. POP!! FWISHHH!!

  8. #47
    Join Date
    Jan 2004
    Location
    PA
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    Quote Originally Posted by Achso017 View Post
    The only thing between the compressor outlet and the service port in heat mode is the muffler and the reversing valve. If it was the muffler I’d have had no pressure on either cool or heat. I haven’t seen a RV cause a pumpdown before either, but what else could it have been? I also saw hot discharge gas bleeding into the suction pipes through the FLIR camera.
    Sure your FLIR wasn't just showing you the RV and large lines on it getting hot from no cool vapor return.

    Hate to bring this up. But, any chance you over heated the new RV when you installed it?

    Never seen an RV cause the hot gas line(vapor line in cooling mode) go into vacuum either.

    Was this a Carrier/Bryant unit.
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  9. #48
    Join Date
    Aug 2018
    Location
    Piedmont Triad, NC
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    Thread Starter
    Carrier. God I hope the things not overheated. I took my time and wrapped in layers of strips and kept it soaked the whole time. I cut the pipes on the bottom ports and brazed them all in one at a time then brazed the whole assembly in. If that didn’t work then next I’m taking the RV out and piping it straight AC with strip heat 😂.

    As far as the FLIR showing me just warm suction gas....I don’t know. I saw streaks of orange/white mixed in with normal dark blue. The streaks extended from the RV a few inches.

    As to a bad RV causing a pumpdown....I keep coming back to this: what else would cause the same thing? Obviously a closed service valve, or some other restriction upstream, but the only two things upstream are the RV and the muffler.

  10. #49
    Join Date
    Jan 2004
    Location
    PA
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    Most carrier residential units have the piston for the outdoor unit in the liquid line service valve at the flare nut. So when you connect your hose, your on the evap side in heat mode. And in cool mode, if that piston is restricted, you can see a pump down on 2 of the ports.
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  11. #50
    Join Date
    Jan 2004
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    PA
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    If the RV is bleeding through, equal pressures.

    If the RV is restricted, the compressor's internal relief would go open up, and you get a loud hissing.

    But would be a large something to clog a RV.
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