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  1. #1

    Changed capacitor it was a temporary fix is my problem the fan motor?

    I am trying to help my parents and fix there a/c which has been down most of the summer after buying a new unit (upstairs) and old unit serviced (downstairs) and having both jobs done improperly. I assumed all was well since he was there a couple of months ago but after visiting I find out it is anywhere from 85 or higher day to 78 at night. They of course believe the nice man will be back to fix. He will not.

    So I decide to take my limited skill set to it and see what I can do. Anyway the downstairs unit had a bad capacitor that must have ran constantly with it bad for 2 moths or so fan was spinning but not at proper speed. Long story short after changing the capacitor the air comes out of vents@ 59-60 degrees cools house now I am back a few days later to check the upstairs unit that was improperly installed (leaky evap line since day one I am sure)and discover the downstairs is only blowing 70-71 degrees out. Is the fan motor bad or is the unit just not cooling properly because it never kicks off because it is over compensating for the upstairs unit previously mentioned?

    Any and all advise or personal experiences would be greatly appreciated.


  2. #2
    Join Date
    Jun 2005
    SW Wisconsin
    Heat goes up the cold air does not; I have two Half-Ton window units.

    I can leave the upstairs unit off, which cools the upper part of the hallway, the bath room & one bedroom &, it does not affect the cooling ability of the first floor unit; nor does it affect the humidity level on the first floor.

    When I walk up the stairs I walk into hot humid air...If I turn the upstairs unit on it cools & dehumidifies the upstairs, again not affecting, at all, the ground floor conditions.

    Length of runtime does not reduce the cooling capacity of the system; did anything change whereby it could be pulling hot unconditioned air into the indoor evaporator coil?

    If indoor supply air is 71-F for some reason the outdoor compressor may not be running...U need a good competent Technician.
    Since U got poor results from a service person we need to try to help your parents find a competent Tech.

    All U need is a good thermometer (digital reading in tenths preferable) & and indoor Humidity Gauge

    1) Helpful; Tonnage of Unit or outdoor condenser model number: ________ only if U can find it.

    2) TXV or, orifice metering device? _______ Only if U know.

    3) Outdoor condenser’s discharge-air-temperature _____

    4) Outdoor air temperature: _______

    5) Outdoor Condenser Air-Temp-Split _____

    6) Need the percent of humidity - away from Supply-Air outlets ______

    7) Indoor Return-Air Temperature ______ Subtract Supply-Air Temperature ______

    8) Indoor temperature-split _______F

    The outdoor condenser temps are very important as they tell us how much heat is being absorbed by the indoor coil & ejected by the outdoor coil.

    *If it is too little or too much for the existing conditions, that provides an indication where the problems may exist.

    --- An example below:
    A Goodman 2-Ton 13-SEER condenser, 800-cfm indoor airflow @ 85-F outdoors; @80-F indoor dry bulb & 50% relative humidity = 103.9-F - 85-F outdoors or an 18.9-F temp-split; with an Indoor temp-split 18 to 19-F.; @ Indoor 75-F & 50% RH condenser temp-split is 14.9-F.
    Last edited by udarrell; 07-24-2012 at 07:43 PM. Reason: Clarity...

  3. #3
    nothing changed since replacing the capacitor it was working great for i guess about 2 days and now it is not cooling much at all the split before was over 20 degrees now it is around 5. Do you think the fan motor could be bad?

    Unit I am working on is a Tran xr-13 if I remember correctly.

    You are definately right about needing a professional I am researching that now but in the meantime any help would be great. I will have to get a pro to do the upstairs repairs but would love to give them at least a good cool down stairs..

    Ill gather the info you asked for tomorrow. I have a infrared thermometer

  4. #4
    Join Date
    Jun 2005
    SW Wisconsin
    Ill gather the info you asked for tomorrow. I have a infrared thermometer.
    A digital air temp thermometer or mercury-TH would be more accurate on those air temps. (with a mercury-TH estimate the tenth increments)

    I have an infrared TH but never tried it on the metal temps of the condenser air discharge grille to see if it compared to the digital TH.

    Nor have I tried it on the liquid-line to see if it's accurate for figuring subcooling temps I used to have the proper test instruments for SH & SC temps; U might try the infrared on the Refrig-lines... may not be accurate though...but might be(?)

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