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Central A/C Coils Freezing


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#1 jmxfour

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Posted June 09 2007 - 5:39 AM

One of my furnance/central A/C units is in the attic. Over the last two weeks, the coils in the duct work freezes and the pipes also freeze. What would cause the coils in the duct work to freeze?

Help before the next heat wave..........................


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#2 dogboy

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Posted June 09 2007 - 6:16 AM

i am far from an expert, but i had a small dehumidifier that froze its coils too, and basically stopped working

i cleaned the coils by spraying them with formula 409 diluted with water

a LOT of dust and dirt later, and it worked fine


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#3 Billy the kid

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Posted June 09 2007 - 7:17 AM

two of the most common reasons the system will freeze up is either dirty filter, or low in freon. first check the filter. that is the faster of the two. if the filter is clean call a HVAC company. Some other reasons can be if you have supply grills closed, return grills blocked and the worst case senario is a bad compressor. and yes I am a certified tech,installer and owner of a company.


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#4 NukeLDO

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Posted June 09 2007 - 1:13 PM

Low on freon


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#5 vafiremn27

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Posted June 11 2007 - 8:19 PM

two of the most common reasons the system will freeze up is either dirty filter, or low in freon. first check the filter. that is the faster of the two. if the filter is clean call a HVAC company. Some other reasons can be if you have supply grills closed, return grills blocked and the worst case senario is a bad compressor. and yes I am a certified tech,installer and owner of a company.

if it was a bad compressor it would not be freezing up.


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#6 Millhunky

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Posted June 11 2007 - 9:25 PM

Check to see if you have air flow over the coil. If the fan is not working, the pipes will freeze. Also check for dirty coil, clogged filter, attic insulation in coil.


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#7 Billy the kid

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Posted June 11 2007 - 11:22 PM

vafireman if the vavles go bad in the compressor it can and will freeze up.


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#8 Ed J

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Posted June 12 2007 - 8:17 AM

Bad valves in a compressor will cause the compressor to lose it's compression ratio......... suction side pressure to go up and the high side down. This cannot cause the evaporator to ice up.
There are a bunch of things that can cause the evaporator to freeze up (insufficient air flow - defective metering device would top my list).
A frozen evaporator can cause liquid to enter the suction side of the compressor which in turn can damage valves, but bad compressors can't make ice .


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#9 Millhunky

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Posted June 12 2007 - 2:20 PM

Bad valves will result in a warm discharge and suction line. Seen this many times when people don't clean their condenser coil on refrigerators.


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#10 vafiremn27

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Posted June 13 2007 - 7:16 PM

Bad valves in a compressor will cause the compressor to lose it's compression ratio......... suction side pressure to go up and the high side down. This cannot cause the evaporator to ice up.

There are a bunch of things that can cause the evaporator to freeze up (insufficient air flow - defective metering device would top my list).
A frozen evaporator can cause liquid to enter the suction side of the compressor which in turn can damage valves, but bad compressors can't make ice .

thanks for the reinforcement.


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#11 Connetquot

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Posted June 13 2007 - 8:23 PM

I believe that Ed has the HVAC crystal ball...



Jeff B.


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#12 renz

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Posted July 27 2008 - 2:20 PM

Center only of window type evaporator freeze, any one know the cuz of freezing? just the center only of evaporator/

thanks


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#13 Ed J

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Posted July 27 2008 - 2:33 PM

It's either dirty or the distribution tube that feeds that portion of the evaporator coil in restricted.
Cleaning is easy, repair of window units is usually cost prohibitive.


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