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  1. #1
    Join Date
    Jul 2005
    Posts
    26
    I have a 2 ton air condition unit for my unstairs. the system during the hottest part of the day is not cooling. I have check pressures and they are right in range per what I learned in class. I did have to add some last year and was thinking there may be a little moisture in the system. Does anyone have any ideas before I remove the refrigerate and replace the filter and recharge?

  2. #2
    Join Date
    Oct 2004
    Location
    Metro ATL
    Posts
    454
    If possible, can you post the measurements you took? Also check the delta T across the evap coil, superheat, subcooling, and amperage on the compressor and it's FLA. Also, if you could post the model number of te unit you have, it will go a long way to helping us diagnose your problem.

  3. #3
    Join Date
    May 2000
    Location
    Indianapolis, IN, USA
    Posts
    34,184
    Check attic heat gain in the ducts. Compare temp coming out of registers with temp leaving coil. Also compare temp entering return grilles with what gets to the coil. If pressures look good, you don't have refrigeration problem. Airflow, duct heat gain, or sizing issue instead.

  4. #4
    Join Date
    Jul 2005
    Posts
    26
    The head pressure was around 270 and the suction was around 78 to 80 the amp draw was 8.9amp and the delta t I dont remember.

  5. #5
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,108
    Originally posted by jhager
    The head pressure was around 270 and the suction was around 78 to 80 the amp draw was 8.9amp and the delta t I dont remember.
    Without outdoor ambient that doesn't tell us anything.
    Same with suction, need to know indoor bd, and wb.

    But at 270 head, it better be real hot outside.

    Have you serviced it lately, like clean the condenser, and evap coils.
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  6. #6
    Join Date
    Jul 2005
    Posts
    26
    The out door temp was 94 yesterday when all this started. and I did not get the indoor db.

  7. #7
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,108
    In order to get a good answer that info is needed.

    indoor wb, and db
    outdoor db
    suction line pressure and temp
    liquid line pressure and temp
    metering device
    coil delta
    brand, model.
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  8. #8

    Wink

    Without knowing the indoor temp. I really can't say if the pressures are right, but judging from your pressures and your description of the problem, you may need to clean your outdoor coil. If that doesn't correct the problem, the system may be overcharged and you may need to adjust the refrigerant charge. Make sure that your filter is clean before adjusting refrigerant.

  9. #9
    Join Date
    Jul 2005
    Posts
    26
    Ok it the weekend and here we go.
    Indoor wet bulb is 67
    the delta T is around 9 to 10
    The head pressure is changing between 300 and 325 psi
    and the suction is changeing between 70 and 80 psi
    the line temp on the suction is 87.4 3 inches from service value.
    and the condensor air is 95.7 going in and 119.7 leaving.

    So If any one can give me an idea before I pull the refrigerate and start over that would be great.

    Joseph

  10. #10
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,108
    When you had to add some last year, was it running in a vacuum.

    Those readings indicate some non condensibles.

    I'd also clean the coils while I was at it.

    So recover, new filter, deep vac and recharge is inline.
    You should fix the leak.

    Your superheat should be about 13 for the conditions you posted.
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  11. #11
    Join Date
    Jul 2005
    Posts
    26

    got it

    You are correct. I did just that and the super heat is 13 now and every is running smoothly. The head pressure and suction pressure is a little high right now but the temperture up stairs is also around 80 degrees. The suction pressure is around 80 and the head pressure is around 320 psi. The suction line temp temp is right on the money at 68.7 it is with end the +- range.
    So thanks for your help.

  12. #12
    Join Date
    Mar 2005
    Location
    Louisiana
    Posts
    211
    Check to make sure that your inside coil is clean, also, turn the power off that powers your inside unit , remove the panel that covers your blower motor, see if the motor and the squirrel cage isn't dirty, if it's really dirty than you'll have to remove it and clean the cage with a hose and vacume the motor the motor but don't you air pressure on the motor, before cleaning the cage though remove it from the motor.
    If all is well with this than it might be time to call in a tech to inspect the system.

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