AC low freon?

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My central AC a 1996 Lennox 3 ton stopped blowing air yesterday, I looked at the air handler coil and it was frozen, filter is new and a 4" so I let it thaw and ran it without the filter thinking added airflow would help. In about 40 minutes it froze again. Airflow unfrozen hasnt changed, its the same out the vents as always so I dont think the blower is bad or any restrictions. When an old unit leaks freon is that usualy the end of life of the compressor or air handler, is it often possible or easy to find and fix a leak without spending alot. I will call a tech today and I hope the leak is small enough that it will last the year but a few days ago it was fine. Will I damage anything running it low on freon for about 30 minute cycles till it starts to freeze and let it thaw, a bit of cool air still comes out.
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That is a classic symptom of 1) Dirty filter, reduced airflow, 2) low Freon. I think you eliminated #1.
If it has never been filled before a charge should at least last the rest of the summer and maybe longer. The units continue to work as the level of Freon drops and then all of a sudden they cross the threshold. Of course if you sprang a big leak it might not last a week.
Most likely it has failed at the evap coil. The bad news is that new replacement evap coils are no longer legally sold so you get screwed into buying a whole new system. Who knows, you might get lucky and it is leaking at a screwed connection.
Your call, but this late in the season I would gas up and gamble. I did that last year in July and made it all the way mid-May of this year. $175 service call and gas bought me a year.
Running as is uses more juice for the same cool but otherwise causes no problems since you have to replace it all anyway. Setting the fan for continuous run will add to your comfort level.
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Colbyt
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I agree. Most probably low freon. I've never heard any business about not selling replacement A coils before so color me skeptical on that. A good service company will have a leak detector and should be able to find anything but the very small leaks. If it is very small them charging it once a year often is enough. Many leaks are easily repaired. But any complicated repair will force you to consider a replacement system given the age.
It won't hurt it to run it for brief periods as long as you shut it down when it the coil begins to freeze. Problem is that will happen pretty quickly unless you are in a dry location.
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Colbyt wrote:

I think you may be confused. In most places it is illegal for a scrap dealer to buy a used evaporator coil - because the thieves have been chopping them loose to sell for scrap - but a homeowner can still buy a new one.
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That does make more sense.
In any case find the leak if possible first. If they can't find it, charge the system and see how long it lasts. Charging once a year may fit better with your situation if you need to get by for a few more years. It is normally a small amount of loss to cause the evap temps to drop below freezing, sometimes just a few ounces. Beyond that the system stops cooling completely.
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I got lucky a few minutes ago, the tech came out fast, and a big leak was found on the copper elbow on a pipe comming out at the top of the compressor, so a guy is comming back to braise it. Even more lucky since he wanted 300$ to use his sniffer to do a leak test, I heard it comming out and first try hit the leak with my finger, its a big leak and I saw vapor. But he said they will replace the pipe, why cant they remove and clean and reuse what is there? 300 for a leak test? I bet it will be, hope no more than 500 for a brazing and refill, he said the system must be evacuated to braise it, so does 500 seem about the price they will charge, maybe I should call for a price first. Well at least its not looking like a new unit which would have to be next year, and im lucky since its 72 out, the coolest day in a over a month
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It does have to be evacuated to be brazed. But you probably don't have much left if it was leaking that much. As a diy'r I'd just fix the leak without replacing any pipe. But I can see that a pro might be conncerned that the elbow has stress issues or was thin somewhere. Remember anything that he does, he's not going to have to want to explain that a new leak a inch away was not his fault.
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Just make sure that they thoroughly evacuate the system before it is re-charged. Many technicians will not take the time and it does take a few hours. The best way is to evacuate and then put in some nitrogen and then evacuate again and repeat.
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That ain't happening. It's a 96 system. The op is not going to want to pay that many hours. Run some nitrogen while brazing, pull a vacuum, and charge.
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Only a concern if the suction pressure is below atmospheric.
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Wow, you guys can't help it if I don't charge enough. 300 for a leak check, and 500 to fix one braze joint, and refil the system? Eight c'notes sounds like a lot of money, to me.
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Stormin Mormon wrote:

Considering that they legally have to drag a refrigerant recovery machine out to recover the refrigerant from the system before they can braze it, and the recovery process takes some time, then they have to evacuate the system and recharge it, it's probably not a lot of money.
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No, it is a bit high. Doesn't take all that long to pump the remaining down into the compressor. Then recover what's left if any in the lines. Then braze, vacuum, and charge. Unless there is some other issues 2 or 3 hours max.
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What should the job cost, I have a quote of 470 for the total job, the initial service trip and tomorrow another tech come by to fix the leak and recharge it. I am having them do it since they installed it, are a quality company and warranty the repair. But its like anything else, you charge what the market bears - what ever you can get.
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That's acceptable. It might seem a little high but they're including the initial trip. If you don't go with them they are going to hand you a bill for $100 to $150 for the first trip.
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I paid the first trip, it was 150 but discounted to 75 since they are comming back. They are a good company, and it could have been 10 x worse so I shouldnt complain, im lucky yesterday was the coolest day in a month, im lucky ive had central Ac at all.
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House call. Three or four hours labor. They may want to recover all the old freon and put in all new freon. I'm not sure what others charge. But, I'd work it out as 60 trip charge (local to me). $50 an hour labor, and $30 a pound for refrigerant. That could total out $400 without too much effort. Sounds like they aren't too far off. It's still a pile of money.
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On Jul 30, 6:09pm, "Stormin Mormon"

When you are broke any repair is alot of money. When I think this month I might get some back bills paid off I get new ones to keep me broke.
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The old cliche fits, too much month left over at the end of the money. Walmart has window shakers from about a hundred bucks and up.
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