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  1. #1

    A/C not cooling, but tech said no problem?

    I have had trouble with my A/C not cooling my house. I live in Houston, TX. I had 2 techs out, one said I needed to install TXV, the other said TXV would not help but said he did not see any problems even though the indoor temp drop was only 10 deg. I would like to get your advice so I can be informed for the next tech that comes out.

    I have a split system, unit 1 is a 2.5 ton, 10 SEER York model #H2RA030506D. Inside evaporator is 3 ton, model #ASFM364010T. Horizontal furnace (air handler) model #P3HUA12N04801C. Outdoor temp 92 deg, 55% humidity, condenser air discharge 106 deg. Suction line pressure 65, suction line temp 78 = superheat 38 deg(used P/T chart). Head pressure 260, high pressure line temp 109(measured at valve) = subcooling 13. Indoor temp at return 80 DB, 68 WB; at supply 70 DB, 59 WB.

    Unit 2 is a 3.5 ton, 10 SEER York model #H1RA042506D. Inside evaporator is 4 ton. Horizontal furnace (air handler) model #P3HUB16N06401C. Outdoor temp 98 deg, 54% humidity, condenser air discharge 123 deg. Suction line pressure 90, suction line temp 85 = superheat 30 deg. Head pressure 280, high pressure line temp 118(measured at valve) = subcooling 7. Indoor temp at return 81 DB, 69 WB; at supply 71 DB, 60 WB.

    Thanks for any thoughts.

  2. #2
    Join Date
    Jan 2005
    Location
    USA
    Posts
    1,460
    I recommend getting a reputable company to give a second opinion. Unfortunately we can not give technical support to homeowners or do it yourselfers. Somebody here should be able to give you the name of a good company. They would need you to list your area sounds like Aridzona. Information is dangerous to you and your equipment in the wrong hands.
    Give the company the same info you gave us here and they may be able to help. Also let them know if the unit has ever worked properly as far as you know, that would answer any sizing issues you may or may not have. As far as txv's go, if they are installed properly they work well but if the system is sized properly and charged correctly there should be no issue with the piston as long as it is the right one for your systems. Sorry I hope this helps. Good luck.
    "It's always controls"

  3. #3
    Join Date
    Jun 2005
    Location
    SW Wisconsin
    Posts
    5,006
    Quote Originally Posted by Bols View Post
    I have had trouble with my A/C not cooling my house. I live in Houston, TX. I had 2 techs out, one said I needed to install TXV, the other said TXV would not help but said he did not see any problems even though the indoor temp drop was only 10 deg. I would like to get your advice so I can be informed for the next tech that comes out.

    I have a split system, unit 1 is a 2.5 ton, 10 SEER York model #H2RA030506D. Inside evaporator is 3 ton, model #ASFM364010T. Horizontal furnace (air handler) model #P3HUA12N04801C. Outdoor temp 92 deg, 55% humidity, condenser air discharge 106 deg. Suction line pressure 65, suction line temp 78 = superheat 38 deg(used P/T chart). Head pressure 260, high pressure line temp 109(measured at valve) = subcooling 13. Indoor temp at return 80 DB, 68 WB; at supply 70 DB, 59 WB.

    Unit 2 is a 3.5 ton, 10 SEER York model #H1RA042506D. Inside evaporator is 4 ton. Horizontal furnace (air handler) model #P3HUB16N06401C. Outdoor temp 98 deg, 54% humidity, condenser air discharge 123 deg. Suction line pressure 90, suction line temp 85 = superheat 30 deg. Head pressure 280, high pressure line temp 118(measured at valve) = subcooling 7. Indoor temp at return 81 DB, 69 WB; at supply 71 DB, 60 WB.
    Thanks for any thoughts.
    WOW, that unit 1 10-SEER data is interesting.
    How in the world could they tell you that it was doing okay?

    First, a 14-F condenser split is unacceptable on a 10-seer system, with those conditions it should be above 20-F.

    That immediately tells you that it is not discharging anywhere near its nominal BTUH Rated Capacity.

    I don't know what your indoor CFM is, but I ran it as 1,000-CFM for a 2.5-ton system.
    My CFM estimate could be way off on both, which would change all the figures.

    With the data you gave, a psychrometric says,
    the sensible is around 10,093-BTUH.
    The latent around 17,390-BTUH, high latent ratio compared to low sensible ratio.
    That would be a total of around 27,483-BTUH for a nominal 30,000-BTUH Rated system, not unusual.
    Data is way off the scale.
    ----------------------------
    Unit 2 10-SEER
    A mere 10-F split indoors, yet a fairly high 25-F condenser split!
    Humidity 54%, possible high infiltration rate of very humid air, causing a high latent load?
    High SH, low SC, could be drawing hot humid air into the Return or high infiltration rate.

    I ran it at 1400-CFM through the E-Coil for a 3.5-ton system.
    Again, low sensible ratio, around 14,097 BTUH.
    High Latent ratio of around 25,109-BTUH
    Total around 39,202-BTUH.

    Do NOT quote my figures to anyone as being scribed in stone, they are simply approximations by using software! The software program may not be accurate!

    Where is the high latent load coming from?
    The sensible load capacity appears to be overwhelmed with the latent load.
    Find a pro that knows how to analyze & locate what is causing these results!

    - udarrell
    Last edited by udarrell; 07-20-2008 at 08:54 PM. Reason: Had typo error on total BTUH estimate on unit one - My CFM estimate could be way off on both.

  4. #4
    Quote Originally Posted by udarrell View Post
    WOW, that unit 1 10-SEER data is interesting.
    How in the world could they tell you that it was doing okay?
    [B]

    - udarrell
    Thanks for the reply. The tech said everything was ok because he did not take any temps, just put guages on and put his hand over the condenser exhaust air.
    Can anyone recommend a company around Houston?

  5. #5
    Join Date
    Jul 2001
    Location
    Gold Coast of Connecticut
    Posts
    4,619
    Aire Serv of SW Connecticut- Gas heat, dual fuel and central a/c systems installed and serviced

  6. #6
    Join Date
    Jul 2007
    Location
    SA
    Posts
    127
    I would suggest hallmark or Airtron. Both good and honest

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