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  1. #1
    Join Date
    Jun 2005
    Posts
    3

    Confused

    facts:
    Location: Southern Middle TN
    Out Side Temp 84
    TemoStat setting 77
    Room Temp. 60" off floor @ termostat 77
    Return Temp 24" off floor 69
    supply Temp closest vent 53
    Ceiling Temp 78

    Turned unit off room temp 1 hour later 77

    Problem: termo set at 77, unit will never shut off even though room temp reads 77, units continues to run but temp never drops lower then 77. I thought it might be to much heat transfer from attic. but ceiling temp disproves this. Duct work is in the crawl space. I had the unit services about 3 weeks ago. Tech cleaned the unit said it was in good shape, needed just a touch of freon. Thanks Hammy

  2. #2
    Join Date
    Jun 2005
    Posts
    3
    I guess i should have posted the question: Why will my unit not shut off once reaching set point? Hammy

  3. #3
    Join Date
    Aug 2002
    Posts
    490
    if your thermostat fan switch is on on the fan will run all the time.
    if your thermostat fan switch is set on auto it will only come on when the thermostat calls for cooling.
    check your return filters in the house little air flow that will keep the house from cooling.
    cause a/c to run day and nite

    if it is not any of these simple problem's
    then you need to call a tech to come out and fix it
    hope that helped

  4. #4
    Join Date
    Feb 2003
    Location
    S.W. PA
    Posts
    3,298
    ok first of all there is alot of room at 77 degrees so you dont even know if it is reaching the exact setpoint ie getting to 77.8 and set point is 77.2 just first thought but then the question becomes why wont it get below 77

    have you changed ANYTHING? different curtains? windows, doors?

    how much insulation do you have and how did unit work before?

    also is you ductwork flex and did tech check that too?

    just a few things to think of before you have tech come back out

  5. #5
    Join Date
    Feb 2003
    Location
    Huntsville,AL
    Posts
    4,125
    are your ducts sealed with mastic -- seams & joints? insulated?

    are all rooms within 3F just after blower shuts off?

    any shade or window film on west & south?

  6. #6
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    With the difference in temperature ,from 24" to 60" high,it's likely an air flow probelm.With floor or baseboard suppies ,and low air flow,the cool air may not be getting high enough into the space.

  7. #7
    Join Date
    Jun 2005
    Posts
    3
    Answers to questions posed:
    Nothing physically has changed about the house. Or the system. The filter is new. there is no window film on any windows . no windows on the south side. i have not seen the air ducts as they are in the crawl space. i do not know what kind of duct work it is . the unit worked fine 2 years ago. i noticed toward end of A/C season last year the unit ran a lot. So that is why i had it serviced and cleaned this year. fan set to AUTO. on trying to check temp differential, where should the thermometer be placed? I have floor vents and the return is at floor level at the end of the hall. Thanks for your insight. Hammy

  8. #8
    Join Date
    May 2002
    Location
    Colorado
    Posts
    697
    I think you should have someone inspect your duct system and fix any leaks with mastic. If duct tape was used during installation it may have deteriorated. This could cause substantial leakage or even a separation at a duct joint.

  9. #9
    Join Date
    Feb 2003
    Location
    S.W. PA
    Posts
    3,298
    agreed have the ductwork checked

  10. #10
    Join Date
    Sep 2004
    Posts
    172
    Not clear on if the compressor is still running after the 77f set point is reached, or is it just the blower fan running not cutting off? Is this one of the variable capacity units or something?

  11. #11
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,556
    It took just alittle gas?

    I'd wonder if the tech actually checked, let alone cleaned the indoor coil.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  12. #12
    Join Date
    Dec 2002
    Location
    Rochester, MN
    Posts
    5,305
    Lot of these new t-stat will make the system run longer even tho the room is at 77, and set point at at 77.. the true temp maybe 77.6 not 77.0..

    So don't worry about it.. Let it do it's job and it will turn like it should.

  13. #13
    Join Date
    Jul 2004
    Posts
    322
    Do you have a two-stage compressor?

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