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  1. #1

    AC repeatedly freezes

    I'll start off by saying I live in Texas, and up until recently I chalked up the AC freezing over several times a week to the fact that it was just too hot outside and the AC was too low. This week however, this temperature has dropped to low 80's and at night low 70's and the AC is still freezing up rather frequently, and it actually seems worse. The unit is a newer (2010) Goodman R22, 2 ton unit, cooling 1300 sq. ft. and the freon has been checked twice, and supposedly is absolutely correct. At this point I've been told a couple of things that might fix the issue, but I just don't know which one I should do.

    So far we've gotten 2 opinions on the subject:
    1) We just bought the house back in January, so the home warranty is still in effect, so we put in a service call when this first started happening. The guy said that from what he could conjecture, the squirrel cage fan was overheating and not working, which would cause freezing and improper cooling. My opinion on this is mixed, because the return air is definitely working, and I can feel air flow from the vents, although the air does not seem to blow as hard as one would expect, so I thought maybe if I was to get a replacement squirrel cage fan, that provided more airflow, this might help for just a few $.

    2) To get a second opinion we had a second company come take a look and his suggestion was more daunting. He said that the coolant lines were much larger than they should be ( 1.25" where it should be .75" and .5" where it should be 3/8" ) and secondly the piston might possibly be the wrong piston, however he said he couldn't drain the system to find out because of all the extra coolant that was in the lines because of them being oversized. So my second option becomes to replace all the coolant lines along with the coolant which I've been told would run about $, which is not awesome, and he wasn't sure if it would actually fix the issue.

    So I'm looking for some expert opinions, because I just don't know enough on the subject to properly decide what course of action I should take, and I'm tired of paying for service calls and finding out at 11 PM that my AC has frozen over and I won't be getting my nice cold sleep.
    Last edited by beenthere; 09-12-2012 at 05:30 AM. Reason: price

  2. #2
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,410
    Low charge and low airflow are common causes of ice ups.

    I'm not buying into the line sizing thing as a reason for an ice up, though.

  3. #3
    Join Date
    Oct 2002
    Posts
    1,248
    I would hope the basic measurements were taken and considered, like low pressure/temperature. Lineset size and pinston issue would be a constant and would not be changing.

    Sartr looking for loose thermostat connection, welded contactor points, bad fan controller board. Have contractor hot wire blower motor at 120 volt side, for one week and see if freezing goes away. Would indicate a control problem.

    Add freeze-stat. This would probably indicate low airflow issue. freezestat resets itself and would mask a problem since you would no longer be having frozen coil.

  4. #4
    Join Date
    May 2011
    Location
    tallahassee,fl
    Posts
    380
    Sounds like u still haven't gotten anyone out there that knows what they're doing

  5. #5
    Join Date
    Aug 2012
    Posts
    2,594
    Sounds like a restriction in the referigerant line IE filter drier perhaps. Linesize not an issue. How could refer charge be just right if system is freezing, there would be an indicator like improper superheat or subcooling if system is freezing.

  6. #6
    Join Date
    Aug 2009
    Location
    Beatrice, NE
    Posts
    1,989
    I wouldn't worry about the line size. If it's a piston issue pressures, temperatures, SH & SC should indicate that as the issue. That leaves airflow. You said the return is working fine but it doesn't feels like as much air from the suppiles as you would expect. That's the clue I would look into 1st. Barring any major leakage the supply and return are interconnected through the blower, so if the return is short the supply is also short, or if the supply is short the return is also short. In other words you can only blow what you can suck and you can only suck what you can blow. If it's the blower overheating I would think it would do it serveal times a day not every several days. Also it would not get worse with lower temps as it wouldn't runa s long.

  7. #7
    Join Date
    Feb 2004
    Location
    michigan
    Posts
    677
    Physically check entering air side of evap coil to confirm air flow isnt restricted. Then look at charge.
    I am the "Wally". All others are meer imitations of the original.

  8. #8
    Join Date
    May 2006
    Location
    Philadelphia, PA
    Posts
    1,375
    An issue with the indoor blower seems reasonable, if troubleshooting was done to determine there is a problem there. I do not understand how the oversize refrig lines would cause this issue. Have blower and indoor coil checked for dirt accumulation.
    Climate Control Solutions for your Home or Office

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  9. #9
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,292
    Let's stick to basics. If this a/c has been freezing up ever since you have operated it, and nobody has verified if the system has proper airflow, that is where to start.

    First of all, change the filter if you haven't done so already. And I mean stop reading my words after this sentence ends, drop what you're doing, and go change the filter.

    Back and filter changed, nice and clean? Good. Next thing to do if a clean filter does not solve this problem is to have a competent tech VERIFY airflow. And I don't mean he sticks his hand in front of several vents and utters the word "good". I mean he carries a manometer with him and checks the total external static pressure (TESP) of your unit and compares it to what the manufacturer's nameplate says the level of TESP should remain below. If TESP is too high and your evaporator is clean, your blower wheel also is clean, then you have ductwork concerns. But if TESP is normal or low, and the evaporator is dirty, and the coil is dirty, get those cleaned. TESP should then be rechecked to see where it is with a clean coil and a clean blower wheel.

    Don't do anything to the refrigerant charge until airflow issues are resolved.

    If your first guy thought the indoor blower was overheating, he should have checked the blower motor's capacitor, and also checked for any lateral bearing play in the motor. He should also have checked the wheel itself to see if it was loaded with dirt, which can add load to the motor (even as it decreases airflow it increases the weight of the wheel. The decrease in airflow can cause the motor to overheat, since the motor depends on good airflow to stay cool). If he did not do that he's only guessing what might be wrong. Not very professional.
    • Electricity makes refrigeration happen.
    • Refrigeration makes the HVAC psychrometric process happen.
    • HVAC pyschrometrics is what makes indoor human comfort happen...IF the ducts AND the building envelope cooperate.


    A building is NOT beautiful unless it is also comfortable.

  10. #10
    Join Date
    Sep 2009
    Location
    Arnold mo
    Posts
    3,939
    Just purchased the home? I would want to check to see if the evap coil if filthy from posible renovation work (dry-wall dust). A good clue would be a dirty blower wheel. Just had one like this earlier this week.
    An answer without a question is meaningless.
    Information without understanding is useless.
    You can lead a horse to water............
    http://www.mohomeenergyaudits.com

  11. #11
    This is the Ask Our Pro's forum. In order to post a response here, you must have verified qualifications and have been approved by the AOP Committee. You may ask a question by starting a new thread.

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    Last edited by jpsmith1cm; 09-12-2012 at 08:02 PM. Reason: non AOP member

  12. #12
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,410
    Hekankah Eteinte


    This is the Ask Our Pro's forum. In order to post a response here, you must have verified qualifications and have been approved by the AOP Committee. You may ask a question by starting a new thread.

    You can find the rules for posting and qualifications here.

    Additional infractions may result in loss of posting privileges.

  13. #13
    Sorry. I missed that part.

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