Why do A/C units decide to stop working on the hottest days?

Discussion in 'Off-Topic' started by rexrocker, Aug 16, 2007.

  1. rexrocker

    rexrocker Active Member

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    Blah...one of our A/C units stop blowing cold air last night. :squint: I sit an await the HVAC guy. Talk amongst yourselves.
     
  2. Jewels450

    Jewels450 Member

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    Mine never even turns off anytime. It just runs around the clock. I wonder if it isn't working or if it is just so hot it just feels like it's not working
     
  3. Meredith

    Meredith Banned

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    Clay, try running the heat on high for about 20 minutes or so then switching back to ac. Our bottom AC unit keeps on freezing lately due the high heat; turning the heat on dailing seems to get the system unfrozen.
     
  4. rexrocker

    rexrocker Active Member

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    Oh nice...I'll give it a try. We've had a problem with the condenser on this unit about 3 years ago, so I'm hoping it's either a) frozen or b) needs some freon.
     
  5. wrxin8or

    wrxin8or Mullitt
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    it stopped working because the world hates you clay
     
  6. Jake

    Jake Active Member

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    about 90% of A/C units (cars AND home) are generally inefficient past 15 degrees below the outside temperature AND if they run at 20 degree below outside temp. Home units WILL FREEZE OVER.
     
  7. Alex

    Alex Community Founder
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    You could need a new filter, new pump, low on juice etc. We just had our motor replaced and it works reasonably well now :)
     
  8. jt money

    jt money 350hp mmm mmm Good!
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    i would check to make sure the out side blower unit is unobstructed. if theres stuff grown up around it or if the fins are really dirty it wont dissipate the heat from the freon properly and thus the inside wont get as cold as it should if at all.
     
  9. Brian

    Brian Active Member

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    Clogged filters, dirty ducts, low refrigerant, weak/broken blowers can all cause the coils to freeze. I currently have to leave me fan "on". Setting it to auto has been causing it to freeze over. Just delaying repairing the blower/controller.
     
  10. Berzerklo

    Berzerklo Active Member

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    The design standard for cooling loads in ATL is holding 74 degrees indoors at 94 degrees outdoors. In these 100 degree days, not only is your cooling capacity too small to keep the space cool but there is less heat transfer between the heat being rejected from your house to 100 degree air. So on the hottest days your AC unit can run constantly and not ever reach the thermostat set point, expediting any kind of problems in the unit.

    Yeah I am a commercial HVAC engineer. We are trying to open like 5 schools in this heatwave, and everything is breaking.:wtc:
     
  11. rexrocker

    rexrocker Active Member

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    [​IMG]

    All good info...the unit is running outside, just not cooling. I've got a guy coming out this afternoon, unless you want to come out and take a look. ;)
     
  12. moose

    moose Infina Mooooooose!

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    I had one of our HVAC engineers spec and install my stuff when I worked for Lennox (in IT), and it's had zero troubles keeping the house at nice and cool temps no matter how brutal it gets. :D

    Meredith: have you changed the filter recently? Coil freezing over is often due to poor flow.
     
  13. BrianGT

    BrianGT Banned

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    I changed the filter last week. I think that the coil might be dirty from the crappy filter that used to be one it.

    --
    Brian
     
  14. cannarella

    cannarella Member

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    We had a whole new AC and ducting installed in the spring and it was well worth the $7300. Our old system (builders grade) would have run 24/7 in this heat to keep it at 82 instead of the nice 73 now that the new unit does.

    +1 on the poor air flow through the coils to cause freeze up. Also check the drain to make sure it is not clogged.
     
  15. rexrocker

    rexrocker Active Member

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    I needed a new capacitor for the fan. $5 part :D A/C is rocking again...the upstairs saw temps about 96 yesterday. Never a dull moment.
     
  16. 4sevens

    4sevens Member

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    Today I jury-rigged a spray system that will spray the ac with water for 10 seconds every 5 minutes
    that the ac is on. $20 raindrip starter kit from home depot. The air blows much cooler
    due to evaporative heat transfer. Similar to what the IC spray does.
     
  17. BrianGT

    BrianGT Banned

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    Yah for IC sprayer for the AC unit!
     
  18. 4sevens

    4sevens Member

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    For $20 it was well worth it.
    Actually I had to rig up a timer and a electronic valve. total cost was $50 but now the ac actually
    turns off for a bit instead of running all day.
     
  19. techlord

    techlord Active Member

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    7300 bucks that is crazy, My TRANE was a bit over 4g's and that was everything furnace, coil, fan, lines, condenser, thermostat the whole kit and kabootle and some custom ducting,. Like you said though does not matter what the temp is outside it works like a charm and monthly's went down tremendously.
     
    #19 techlord, Aug 17, 2007
    Last edited: Aug 17, 2007
  20. cannarella

    cannarella Member

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    Well it came in above the mid range of the quotes we got. We had quotes from 5K up to 8K. Our current system was in the floor and we had the new system put in the attic so it was a complete install of all ducting, inside and outside units, power to both, gas, vent, everything. The old system is still in its same place. I am just pointing the ducts down to the basement and moved the thermostat down there. The guy who did it did an awesome job, not duct board like the others wanted to use. We got a Westinghouse 3 ton unit. 10 year warrenty. It is made by Nordyne.

    Oh and our power bill has the power used as compared to a year ago and we are about 1/4 to 1/3 less then last year at this time. So good money savings.
     
    #20 cannarella, Aug 17, 2007
    Last edited: Aug 17, 2007

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