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  1. #1
    Join Date
    Jun 2019
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    Evap Coil Blockage?

    Here is a picture of my evaporator coil showing only half of the coil sweating. I had a tech out yesterday who checked pressures and said everything looked good. Found a bypass vent wide open causing return air temp to be too low so that will get fixed. My question is this obviously looks like something is wrong with the coil. This is the 3rd coil I've had on this Lennox system. It has been replaced twice under warranty due to the first 2 leaking. I also had my outdoor TXV replaced at the condenser due to the compressor vibration breaking off the bulb line. In total my 3 year old system has had the coil replaced twice and outdoor txv replaced once. The system has been opened up 3 total times. My gut feeling is the system got contaminated and the evaporator coil plumbing has become plugged.Name:  evap small.jpg
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  2. #2
    Join Date
    Aug 2002
    Location
    Southold, NY
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    My gut feeling is you unfortunately haven’t gotten a real tech!

  3. #3
    Join Date
    Jan 2019
    Location
    Vero Beach, Florida
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    Did he even look at the evap coil? The txv sensing bulb is not insulated.
    Did he check super heat and subcool?
    If you have the invoice can you post a pic of it so we can see what he said “good pressures” is.

  4. #4
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    Jun 2019
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    Thread Starter
    He did take a look at the coil because he was supposed to have performed a light cleaning on it as part of the maintenance program I was signed up for when I called for the service. He made a comment that it looked brand new which it is, only being installed for 6 months. He did not record pressures on the invoice, but I was out there while he had his gauges on the compressor. It had a proper 4.6 degree subcool based on the unit specification of 4 degrees. I specifically asked him to check superheat at the evaporator but I'm pretty sure that was not measured considering this is what my coil looks like. He measured the delta across the coil and found only 13 degrees which led him to consider the bypass damper. The bypass damper was found without anything assisting it closed so it was forced wide open every time the blower turned on. It was showing a 13 degree temperature drop with a discharge temperature of 55. The sad thing is this is probably how its been operating since the house was built since there was no sign of the damper controller. I checked in and around the insulation in case it may have fallen off. I've never had any issues cooling through heat spells until now which leads me to believe the root cause is not the damper but somewhere in this coil.

  5. #5
    Join Date
    Dec 2007
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    Quote Originally Posted by Deathpunch0311 View Post
    Did he even look at the evap coil? The txv sensing bulb is not insulated.
    Insulating the bulb is best practices, but most come from the mfr WITHOUT insulation.
    The Food Stamp Program, administered by the U.S. Department of Agriculture, is proud to be distributing the greatest amount of free meals and stamps EVER.
    Meanwhile, the National Park Service, administered by the U.S. Department of the Interior, asks us to "Please Do Not Feed the Animals". Their stated reason for this policy "... the animals become dependent on handouts and will not learn to take care of themselves."
    from an excerpt by Paul Jacob in Sun City, AZ

  6. #6
    Join Date
    Jan 2014
    Location
    New England
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    Opened 3 times? Where's the filter drier located, in the liquid line or does it come from the factory inside the OD unit? When it was opened, did they Pump the refrigerant into the OD unit to make repairs, or recovered what refrigerant was left, was your system ever bone dry anytime during the 3 times it was open?

    Curious what are those wires to the right of the coil, hooks to a freezstat? If freezestat, did that come from the factory or field install?

    Coil looks to have the epoxy coating?

  7. #7
    Join Date
    Aug 2002
    Location
    Southold, NY
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    13* SC with a fully open bypass damper?

  8. #8
    Join Date
    Jun 2019
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    7
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    Thread Starter
    Quote Originally Posted by Bazooka Joey View Post
    Opened 3 times? Where's the filter drier located, in the liquid line or does it come from the factory inside the OD unit? When it was opened, did they Pump the refrigerant into the OD unit to make repairs, or recovered what refrigerant was left, was your system ever bone dry anytime during the 3 times it was open?
    The filter drier is located in the condenser unit outside. I was told a new filter drier was installed when they replaced the outdoor txv. I have no idea how they recovered or pumped refrigerant in during the repairs. I'm pretty sure virgin refrigerant was used at my last repair which was the txv/filter drier replacement. I'm basing this off the fact that the guy told me the repair was done and that he was just waiting on the vacuum pump before recharging the system. I'm not sure if it was ever bone dry or not during those times.

    I really appreciate the feedback from you all, and am interested in what your thoughts are. I was pretty confident the second I looked at the coil that something is not right. At this point, I'm planning on talking with the service manager of the company first thing Monday to demand this gets taken care of. I shouldn't have to be on a message board for professional advice when this company advertises themselves as HVAC professionals. This is the same company who installed it when the home was built and performed all the maintenance since.

  9. #9
    Join Date
    Jun 2019
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    Thread Starter
    Quote Originally Posted by pecmsg View Post
    13* SC with a fully open bypass damper?
    13 degrees was the measured temperature difference from the return air to the supply air.

  10. #10
    Join Date
    Jan 2019
    Location
    Vero Beach, Florida
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    Quote Originally Posted by scarednoob View Post
    The filter drier is located in the condenser unit outside. I was told a new filter drier was installed when they replaced the outdoor txv. I have no idea how they recovered or pumped refrigerant in during the repairs. I'm pretty sure virgin refrigerant was used at my last repair which was the txv/filter drier replacement. I'm basing this off the fact that the guy told me the repair was done and that he was just waiting on the vacuum pump before recharging the system. I'm not sure if it was ever bone dry or not during those times.

    I really appreciate the feedback from you all, and am interested in what your thoughts are. I was pretty confident the second I looked at the coil that something is not right. At this point, I'm planning on talking with the service manager of the company first thing Monday to demand this gets taken care of. I shouldn't have to be on a message board for professional advice when this company advertises themselves as HVAC professionals. This is the same company who installed it when the home was built and performed all the maintenance since.


    EVERYTIME A SYSTEM IS OPENED IT GETS A FILTER DRIER!!!

  11. #11
    Join Date
    Jan 2019
    Location
    Vero Beach, Florida
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    Quote Originally Posted by Bazooka Joey View Post
    Opened 3 times? Where's the filter drier located, in the liquid line or does it come from the factory inside the OD unit? When it was opened, did they Pump the refrigerant into the OD unit to make repairs, or recovered what refrigerant was left, was your system ever bone dry anytime during the 3 times it was open?

    Curious what are those wires to the right of the coil, hooks to a freezstat? If freezestat, did that come from the factory or field install?

    Coil looks to have the epoxy coating?

    Lennox sends epoxy for the second coil replacement.
    Those wires to the right are probably for the float switch. I HATE IT WHEN INSTALLERS DO THAT

  12. #12
    Join Date
    Jun 2019
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    Thread Starter
    Quote Originally Posted by Deathpunch0311 View Post
    Lennox sends epoxy for the second coil replacement.
    Those wires to the right are probably for the float switch. I HATE IT WHEN INSTALLERS DO THAT
    Yes that is correct, the coil is epoxy coated. This apparently was the fix to keep them from springing leaks. The electrical wires are for the float switch.

    The evaporator coil circuits that appear dry in the photo do feel cool to the touch. I don't have any clamp probes to take accurate temperatures so I can't determine how much warmer they are than the others.

  13. #13
    Join Date
    Jan 2019
    Location
    Vero Beach, Florida
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    How long after it was running did you take that pic

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