Central AC is not working


  #1  
Old 07-13-10, 03:38 PM
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Unhappy Central AC is not working

My Central AC is not working well. Please help!

The wind from the vents inside the house is barely cold.

The fan in the outside unit is running, but the wind is not hot/warm. There are two copper tubings connected to the outside unit (as you all know), the one with insulations (going to the house) has some ice on it, so I think the compressor is working, but the one without insolations (coming from the house) is not hot. My guess is there is no flow going through the tubings to carry the heat from the house into the outside unit.

Please advise what I can do.

Thanks!
 
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Old 07-13-10, 04:25 PM
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Is the inside fan running?
 
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Old 07-13-10, 05:13 PM
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Yes, it is. But the wind (from the vents inside the house) is just a little bit cold.

And the wind blowed from the outside unit is not hot/warm.

Thanks!

Originally Posted by Mike Speed 30
Is the inside fan running?
 
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Old 07-13-10, 05:53 PM
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Make sure your filters are all clean/new. if filters are all clean, how about evaporator coil. is the coil clean ? Is the inside air blow strong ?
 
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Old 07-14-10, 09:18 AM
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Thanks a lot for the advice!!! I removed the panel for the evaporator coil, and found out that it is completely wrapped with a very big piece of ice!

So, I am now leaving the indoor unit's fan on to melt down the ice so I can clean up the evaporator coil, as well as replace the filters.

One more question, I cannot shut down the outside unit normally. I don't know the reason. In normal situation, if I turn the thermo control to "OFF", the outside unit will be down almost immediately. But now it doesn't. The fan in the outside unit keeps running even if the thermo control is "OFF" for a long time. Is this behavior related my current ICEY problem? I ended up with shutting down the power on the outside wall next to the outside unit, to shut down the fan in the outside unit.

Thanks a milliion!

Originally Posted by clocert
Make sure your filters are all clean/new. if filters are all clean, how about evaporator coil. is the coil clean ? Is the inside air blow strong ?
 
  #6  
Old 07-14-10, 11:28 AM
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Outside fan is controlled by a contactor in the condensing unit. it may be stuck. (it should spring open when t-stat cuts the power to it. when t-stat send the power to it, the magnetic force pull it close). There are 120v and 240V on that contactor, be careful if you want to do it yourself. cut the power first. and don't touch the capacitor. If it is just stuck, you can use a wood stick hit it a couple of times and hopefully that will lose it. but usually, it is too old, rusted, or.. you may need a new one.
 
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Old 07-14-10, 11:42 AM
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I think I understand what you are saying. I saw the contactor last time when I opened the outside unit. I will be very careful to exam it.

Thanks!!!!!


Originally Posted by clocert
Outside fan is controlled by a contactor in the condensing unit. it may be stuck. (it should spring open when t-stat cuts the power to it. when t-stat send the power to it, the magnetic force pull it close). There are 120v and 240V on that contactor, be careful if you want to do it yourself. cut the power first. and don't touch the capacitor. If it is just stuck, you can use a wood stick hit it a couple of times and hopefully that will lose it. but usually, it is too old, rusted, or.. you may need a new one.
 
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Old 07-15-10, 09:21 AM
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Clocert, thanks so very much! The AC is fixed after following your advices. The worst thing that block the air flow was an old allergen removing air filter.

And the outside fan switch was also like you said stuck somehow. It seems working fine now after I used your way to tap it a few times.

Thanks!!!!

Originally Posted by clocert
Outside fan is controlled by a contactor in the condensing unit. it may be stuck. (it should spring open when t-stat cuts the power to it. when t-stat send the power to it, the magnetic force pull it close). There are 120v and 240V on that contactor, be careful if you want to do it yourself. cut the power first. and don't touch the capacitor. If it is just stuck, you can use a wood stick hit it a couple of times and hopefully that will lose it. but usually, it is too old, rusted, or.. you may need a new one.
 
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Old 07-15-10, 09:47 AM
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Glad to hear that everything is working for you.
 
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Old 07-20-10, 06:38 PM
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The contact points on the control contactor relay probably became pitted & eventually welded together; it will need replacing.

Also, make sure the indoor duct system & blower delivers the proper amount of air to the rooms.
 
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Old 07-26-10, 06:43 AM
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Thanks for the advice! I will keep an eye on it and replace it if it failed again.


Originally Posted by HVAC RETIRED
The contact points on the control contactor relay probably became pitted & eventually welded together; it will need replacing.

Also, make sure the indoor duct system & blower delivers the proper amount of air to the rooms.
 
 

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