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Discussion Starter · #1 ·
Hello, My home central air is not cooling the house. The system is probably 25 years old but has worked pretty well up to now. The compressor is running, the condensor fan is running. The refridgerent pressures are 30 and 175. I opened the panel to the evaporator and the lower couple of coils on each side of the "A" coil are cold and frosted but all of the rest of the coils are barely cooler than ambient. Only the bottom 1/5 of the "A" coil is cold. The larger insulated line out of the evaporator is also barely cooler than ambient if that. Can anyone offer an opinion as to what is wrong? This site has been a great help to me. Thanks
 

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yeah i agree with marty. does it look similar to this? this is a picture of my old corroded coil that was slowly leaking and froze from the top down.

Wood
 

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Discussion Starter · #4 ·
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Yes, The pix you presented could have come from my own camera. That is exactly what my evap looks like. However, I still am not sure what this means. Since my wallet's a little thin, I'm still trying to figure out if the system can be saved. If the system is holding 175 psi then how can it be leaking? What are the normal pressures? Why would a couple of coils be very, very cold and all the rest be ambient. Is the partially cold evap coils a symptom of low freon quantity, or an internal blockage in the evap or something else? I'd sure like to understand this better. Thanks again.
 

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what does the condition of the coil look like? if it is very corroded and rusty like the picture of my old one, it is most likely leaking, but it may be a very slow leak at this point. your pressures are obviously low, those were similar numbers to mine at the time i took this picture (r22 of course). i bought a very cheap leak detector and ran it across the sides of the coil where all the piping is and found several pinhole leaks. it was leaking extremely slowly, so the charge would last about 9 months or so before it would get low enough to freeze the coils again.

if you let it continue to run, it will most likely start freezing up more and more until airflow almost ceases and eventually the entire suction line (the big one) will freeze up completely and there will be a thick layer of ice where it enters the outside condensing unit. when the pressures drop, the refrigerant in the lines evaporates too quickly at the top of the coil, absorbing heat too quickly and freezing the lines. when the pressures are normal, the refrigerant evaporates slowly over the entire length of the piping withing the coil, making the entire coil cool but not freezing cold.

i replaced my coil with a new one and it has been running for a year with no problems.
 

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I'm Your Huckleberry
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It means your evaporator coil, within those circuits that are freezing, is leaking refrigerant and you need an evaporator coil.

Happens all the time with age.
 

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I'm Your Huckleberry
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it could also mean that you have a restricition in that evaporator coil. I had one two days ago that in the middle of the coil the two circuits were freezing and only in the middle and the system held (20 psi-very low suction/200 psi-high due to restriction) but would not take refrigerant to charge it.

You need a coil, no two ways about it.
 

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price-wise, i think i got a quote for $1200 - $1500 on a 2.5 ton coil, depending on retrofit since it was an older 10 seer coil that you can't get anymore.

i did it myself for about $400 including refrigerant charge plus some tools. however, this is not a recommended DIY job. it is a ton of work and requires some skill and knowhow, luckily i have a buddy that is in the HVAC business and helped me out.
 

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If cash flow is a big issue then just have the system filled up. It will still leak out but maybe the leak will be slow enough that the system will cool for this summer. Having a company replace the coil will be very expensive and you shouldn't put that kind of money in an old system.
 
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