Page 2 of 2 FirstFirst 12
Results 21 to 26 of 26

Thread: Subcooling not increasing.

  1. #21
    Join Date
    Sep 2002
    Posts
    29,949
    Post Likes
    In general; if adding refrigerant to an operating refrigeration system does not increase liquid subcooling - the condenser's liquid capacity has not been reached yet. <g>

    PHM
    ---------

    Quote Originally Posted by Laeeq421 View Post
    Hi experts. I can use some guidance.
    Charging a txv system with subcooling is simple.
    The problem I ran in today was really weird. The unit had low on gas and was freezing ice.
    After melting all ice I started adding refrigerant.
    The suction line gauge showed the pressure at 100 means temp was around 30deg or so so no wonder it was freezing. I added 410a as system needed the charge.
    My pressure increased. I charged till about 125psi on suction line and ~300psi on liquid line. My temperature on liquid line remained high. About 96deg (saturated temperature in the middle of condenser coil -reading on high side gage) and 94deg on liquid line temp. That’s just 2deg subcooling. My outside temp was around 81deg. Even adding refrigerant don’t help increasing the subcooling. This is odd. It should be simple but in this unit the liquid line temp increasing with the charge. What is wrong.
    It’s a 10yr old system Rheem 410a. I don’t see subcooling data anywhere on the unit.
    Please help.

    System type split (outside condenser and garage air handler)
    Refrigerant 410a
    Ice was built up on inside air handler and outside by the pilot valve (pic attached)
    No subcooling data
    16seer unit - Rheem 10yr old.
    Attachment 823891
    PHM
    --------
    The conventional view serves to protect us from the painful job of Thinking

  2. #22
    Join Date
    Aug 2002
    Location
    Southold, NY
    Posts
    32,932
    Post Likes
    “saturated temperature in the middle of condenser coil -reading on high side gage”

    ? ? ?

  3. #23
    Join Date
    May 2006
    Location
    Austin, Texas
    Posts
    678
    Post Likes
    You said 81 degrees ambient and 103 degrees condenser discharge. On a 16 SEER system, that condemser coil is NOT clean!

  4. #24
    Join Date
    Apr 2021
    Posts
    8
    Post Likes
    Thread Starter
    Quote Originally Posted by pecmsg View Post
    “saturated temperature in the middle of condenser coil -reading on high side gage”

    ? ? ?
    Nope. Air handler coil


    Sent from my iPhone using Tapatalk

  5. #25
    Join Date
    Aug 2019
    Location
    Maryland
    Posts
    90
    Post Likes
    How can you say it’s no liquid line restriction without taking superheat readings


    Sent from my iPhone using Tapatalk

  6. Dislikes VTP99 disliked this post.
  7. #26
    Join Date
    May 2006
    Location
    Deep Southeast
    Posts
    18,094
    Post Likes
    Quote Originally Posted by Laeeq421 View Post
    Some more data.
    Yes TXV system. I checked by removing cover.

    Before I got to the job site the costumer had the AC turned off for atleast 24hours so all ice was fully melted. Coil was clean

    When I got to the site and charged the system (yes slowly), it started cooling with the gauge readings I provided (125 and ~300). The house cooled to 75deg or so inside temp.

    I didn’t check the superheat but will measure today.

    The unit has been cooling for 24hours now with no freezing issues and the house is cooling (75deg inside).
    Inside blower airflow is good (running full speed) and airflow out of ducts are good also.

    The difference in ambient temp and the air blowing out of outside condenser was about 22 degrees so it is removing heat.
    Both indoor and outdoor coils were clean. I did change the inside filter just for kicks.

    Nonrestriction on liquid line. Temp outside before dryer is same as after dryer and also same by air handler.

    With all those the subcooling won’t come up. With more charge the head pressure keeps increasing but also the liquid line temp keeping the subcooling low. I don’t want to overcharge.

    Yes my gauge is good.
    Please help.
    You really aren't giving enough information for anyone to help you with the diagnosis, but it sounds like to me that the issue was low on charge. And I'll speculate that when you attempted to add more refrigerant, the indoor temp was below 70°, which can create problems when charging. I've had similar results and returned when temps were warmer and was able to finish charging as expected.

    An example of the kind of information that would help us help you:

    Name:  MQ Data points.PNG
Views: 27
Size:  72.2 KB

Page 2 of 2 FirstFirst 12

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •