air conditioner freeze up

Can anyone tell me what causes the coils in the interior unit of a central air conditioning system to freeze up? They are covered in ice and a puddle of about 2 inches of water is at the base of the unit. Any ideas? Thanks!
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GGF3 wrote:

Restricted airflow (ie: dirty filters) or refrigerant undercharge. If the latter, you likely have a leak.
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One other outside possiblity is that the outside unit is running all the time, even when no cooling is called for- thus no fan in the ultimate case of restricted air flow. I had a unit that was mis-wired, and it did this, as stated if the outside unit runs and no blower you have the ultimate restricted airflow case
It could be mis-wiring or a stuck contactor in this case.

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wrote:

Either low on Refrigerant or air flow.
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GGF3 wrote:

Probably low on freon, very dirty cooling coils, very dirty filter, or a combination of the above.
--
Robert Allison
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Others gave good answers. It can also ice up if the outside temperature is too low. Some people here in the NE are already calling with the problem. Nights here are in the 40's. Misdirected air can also cause it. I've seen people try to run these behind draperies and curtains.
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The temperature of the coil dropped below the freezing point. Humidity froze on the coil, and the air flow was restricted. And finally stopped.
Call an HVAC guy, and have the system serviced.
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Christopher A. Young
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This is Turtle.
Here is your best possible of it being one or bunch of these.
Low of freon.
Dirty Filter
Dirty or plugged up evaperator coil or Dirty blower wheel of blower.
Evaperator fan motor failing at times but maybe a fan relay.
Inefficent Compressor with just the right inefficentiness to freeze the coil.
Sticking Condenser contractors to keep condenser running all the time while evaperator section cycles off.
Thermostat set below 58F and let to run all nite.
The thermostat not turning on evaperator blower at times and turning on the condenser.
That is it for now but there could be some more.
TURTLE
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Good list Turtle. That covers the most likely causes.
Stretch
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ill second the opinion that the air filter is totally clogged or the coil isclogged. the blower fan gets pretty packed also causing lower air flow .you gotta move alot of air over the coil to keep it from freezing. lucas
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