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  1. #1
    Join Date
    Feb 2016
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    Cherryville, NC
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    Unique issues causing coil to freeze.

    So typically you would think a cool freezes up because of low refrigerant or low airflow being the two most common culprits. What are some weird issues you guys have seen to cause a coil to freeze outside of the normal issues?

    I feel like such an idiot and not sure I should even admit to it but here it goes. I installed an ICP 5ton air handler up flow in a house for a friend. He had the condenser changed last year by someone else, Goodman 5ton heat pump. Unit froze up first night it was installed, charge was close but not perfect because it had dropped in temp to about 60 degrees and was 78 in the house but close enough. I came back and determined txv was stuck and not metering the refrigerant properly, most likely the real reason my charge wasnít perfect. I replaced txv from supply house and was able to get charge a lot closer to where it needed to be, still not perfect. Unit froze again 2 days later, I went back and as soon as I walked into room where unit sits the condenser comes to life. Now the thermostat has been off all day and the coil is a block of ice. No call for fan at tstat wires in air handler and blower wasnít running but I had 25v on yellow and reversing valve. I replaced wire to thermostat and the thermostat for good measure as it was older digital. Now I would never in a million years check to see why a unit was freezing up by turning the thermostat off and waiting for it to run. Anyway, thought that fixed it, customer tells me today itís froze again so I call the guy that put in condenser and ask if heíll go look at it and give me his opinion as to what is going wrong. He tells me they gave me a 2.5ton txv to replace the original 5 ton when I had the first issue. Iím calling supply house tomorrow to verify this. This has been a crazy week and a half.

  2. #2
    Join Date
    Jul 2018
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    Quote Originally Posted by Prowelder View Post
    So typically you would think a cool freezes up because of low refrigerant or low airflow being the two most common culprits. What are some weird issues you guys have seen to cause a coil to freeze outside of the normal issues?

    I feel like such an idiot and not sure I should even admit to it but here it goes. I installed an ICP 5ton air handler up flow in a house for a friend. He had the condenser changed last year by someone else, Goodman 5ton heat pump. Unit froze up first night it was installed, charge was close but not perfect because it had dropped in temp to about 60 degrees and was 78 in the house but close enough. I came back and determined txv was stuck and not metering the refrigerant properly, most likely the real reason my charge wasnít perfect. I replaced txv from supply house and was able to get charge a lot closer to where it needed to be, still not perfect. Unit froze again 2 days later, I went back and as soon as I walked into room where unit sits the condenser comes to life. Now the thermostat has been off all day and the coil is a block of ice. No call for fan at tstat wires in air handler and blower wasnít running but I had 25v on yellow and reversing valve. I replaced wire to thermostat and the thermostat for good measure as it was older digital. Now I would never in a million years check to see why a unit was freezing up by turning the thermostat off and waiting for it to run. Anyway, thought that fixed it, customer tells me today itís froze again so I call the guy that put in condenser and ask if heíll go look at it and give me his opinion as to what is going wrong. He tells me they gave me a 2.5ton txv to replace the original 5 ton when I had the first issue. Iím calling supply house tomorrow to verify this. This has been a crazy week and a half.
    Clogged drain pan. If the water touches the coil, it will freeze up very quickly.

    Sent from my SM-G960U using Tapatalk

  3. #3
    Join Date
    Mar 2016
    Location
    Pahrump, NV
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    What was your superheat with the 2.5 ton TXV?
    It's an upside down world we live in.

  4. Likes Metalman0880 liked this post
  5. #4
    Join Date
    Nov 2011
    Location
    USA
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    Quote Originally Posted by Prowelder View Post
    So typically you would think a cool freezes up because of low refrigerant or low airflow being the two most common culprits. What are some weird issues you guys have seen to cause a coil to freeze outside of the normal issues?

    I feel like such an idiot and not sure I should even admit to it but here it goes. I installed an ICP 5ton air handler up flow in a house for a friend. He had the condenser changed last year by someone else, Goodman 5ton heat pump. Unit froze up first night it was installed, charge was close but not perfect because it had dropped in temp to about 60 degrees and was 78 in the house but close enough. I came back and determined txv was stuck and not metering the refrigerant properly, most likely the real reason my charge wasnít perfect. I replaced txv from supply house and was able to get charge a lot closer to where it needed to be, still not perfect. Unit froze again 2 days later, I went back and as soon as I walked into room where unit sits the condenser comes to life. Now the thermostat has been off all day and the coil is a block of ice. No call for fan at tstat wires in air handler and blower wasnít running but I had 25v on yellow and reversing valve. I replaced wire to thermostat and the thermostat for good measure as it was older digital. Now I would never in a million years check to see why a unit was freezing up by turning the thermostat off and waiting for it to run. Anyway, thought that fixed it, customer tells me today itís froze again so I call the guy that put in condenser and ask if heíll go look at it and give me his opinion as to what is going wrong. He tells me they gave me a 2.5ton txv to replace the original 5 ton when I had the first issue. Iím calling supply house tomorrow to verify this. This has been a crazy week and a half.
    Low air flow and starving evaporators (low charge, liquid restrictions) are the usual causes. Occasionally there's non-uniform air distribution across the coil (for some reason) but that's still airflow. Some times there's non-uniform refrigerant distribution...I've never seen that but cases have been posted. Of course if the condenser is running and the air handler isn't, the coil will frost.

    You stated twice "the charge was close but..." If you desire sensible answers, you got to provide sensible information. Let the readers decide if the charge is close or not.

    You should have been charging to subcooling with a TXV fed coil. And with 60˚OD, you can charge to subcooling with no problem. The 78˚ ID should have generated a saturated suction temp 45˚ or so if the airflow is 350+ CFM/ton. The saturated condensing temp should have been around 80˚ (60 + 20). Superheat would be something reasonable if the valve was working right.

    You see anything like that?

    Quote Originally Posted by wreakingHaVAC View Post
    Clogged drain pan. If the water touches the coil, it will freeze up very quickly.

    Sent from my SM-G960U using Tapatalk
    The water won't freeze if the coil temperature is 40˚+

  6. #5
    Join Date
    Mar 2016
    Location
    Pahrump, NV
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    Quote Originally Posted by Saturatedpsi View Post

    You should have been charging to subcooling with a TXV fed coil. And with 60˚OD, you can charge to subcooling with no problem. The 78˚ ID should have generated a saturated suction temp 45˚ or so if the airflow is 350+ CFM/ton. The saturated condensing temp should have been around 80˚ (60 + 20). Superheat would be something reasonable if the valve was working right.
    What I was thinking with my question about superheat was that with a grossly undersized metering device, the sub-cooling might have been within reasonable range, but the superheat would have remained very high.
    It's an upside down world we live in.

  7. #6
    Join Date
    Jan 2004
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    PA
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    Quote Originally Posted by David Goodman View Post
    What I was thinking with my question about superheat was that with a grossly undersized metering device, the sub-cooling might have been within reasonable range, but the superheat would have remained very high.
    That is what would/will generally happen. Except on a low load day, like when its 60 outside, and the indoor humidity is also low. The SH won't be real high. But once it gets above 70 outside and the indoor RH increases, the SH will increase.
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  8. #7
    Join Date
    Feb 2016
    Location
    Cherryville, NC
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    Thread Starter
    I had 10 degrees superheat and 12 degrees subcooling after I changed txv

  9. #8
    Join Date
    Feb 2016
    Location
    Cherryville, NC
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    Thread Starter
    I didnít list exact pressures and temps because I didnít write it down and it was over a week and a half period. I know what the charge should have been and when I say it was close yíall can assume it was close. (I know thatís not always the case). My main point I guess is through this whole ordeal there were things causing this to freeze up that weíre outside of normal issues you would normally look for(like condenser running on itís own). I also had no way to tell they give me the wrong txv and not sure what ďchartĒ the guy I had look at it yesterday was referring to. How do yíall double check behind the counter guy to make sure txv is correct part?

  10. #9
    Join Date
    Jul 2007
    Location
    East Haven,CT
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    Quote Originally Posted by Prowelder View Post
    How do yíall double check behind the counter guy to make sure txv is correct part?
    I look up part #s myself on my iPhone and when I call supplier I have info ready. Some manufacturers and suppliers either have an app or have parts breakdown on web. Iíd rather take a few minutes to find correct part than be given wrong one and lose money.



    Sent from my iPad using Tapatalk

  11. #10
    Join Date
    Feb 2016
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    Cherryville, NC
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    Thread Starter
    Would you guys with lots more years of experience ever think to turn unit off and see if unit keeps running? The homeowners didnít tell me the outdoor unit didnít always cut off when they turned unit off till the last time I was there and changed the thermostat wire and found out for myself what it was doing.

  12. #11
    Join Date
    Jul 2007
    Location
    East Haven,CT
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    Itís pretty much 1st thing I do. If itís frozen up then I turn AC off and switch fan on. If CU is still running I look for reason why.


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  13. #12
    Join Date
    Feb 2016
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    Cherryville, NC
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    Thread Starter
    Well when they tell me itís froze up, I tell them to turn it off and I look when I get there and it is off but hasnít thawed, my first reaction to that is they just turned it off right before I got there not that the condenser is running on itís on. Iíve seen people do that all too often. This last time I just happen be there when the condenser started running with thermostat set to off.

  14. #13
    Join Date
    Jul 2007
    Location
    East Haven,CT
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    In my experience this is what usually happens when a customer says itís frozen up. They saw a little bit of ice on suction line outside so I tell them turn it off and Iíll be out in a few hours, so now itís getting hot inside and they look at pipe and ice is gone so they put in back on cuz they think itís fixed itself so when I get there itís running. Been times Iíve actually have gotten there and system is off but CU was still running for variety of reasons.


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