DIY Evaporator Coil Replacement?

lambert_johnFebruary 20, 2007

Last summer, my 10-year old upstairs home AC unit starting blowing hot. It's a split unit, condenser/compressor on the outside, and air handling unit on the inside in a little cubby hole in the attic.

The air conditioning guy came out and told me there's a leak in my evaporator coil. Evidently, in all the turns and bends of the coil, there is a hairline crack somewhere that's allowing the freon to slowly leak out. He went ahead and filled the unit with freon and it worked fine for about 3 months - enough to get me through the summer.

I asked him what he would charge to replace the evaporator coil and he hit me with a $1400 quote. Yow! So my brain started thinking, "How hard would it be to do it myself?" I've never worked on a home AC unit, but have fixed just about everything else in my house myself. questions are, obviously, is this something I can do myself? If so, do I need any special licenses to do it? Other than the tight location of the current coil, is it as simple as removing the old one and putting the new one in? Is there anything special I need to pay attention to in order to replace the evaporator coil? Is it welded in? Screwed in? Where do I buy the replacement coil at? Lastly, is there a good AC DIY book that I can reference to get me through this project? Thanks for your help everyone! I appreciate it.

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Simple answer this is not a do it yourself job or HD and lows would have these in stock...........
1. It takes a year of schooling that cost over 10,000.
2. There's refrigeration laws.
3. Its not only soldered in but you have to use refrigeration sodder. some people braze.
4. Possible sheet metal fabrication involved. Them tools Aren't cheap.
5 it will probably take a refrigeration mechanic all day to do it correctly......... Its not a 2 hour job. The fact of going in the attic and back to the condenser a few times. And back to the attic with tools may take from 8 am till 1 or possible 2pm. then also getting a possible piece of metal fabricated. And soldering the lines back together. A job like this isn't easy and there maybe two people to actually do all of this...............
That was the long version.......... But it is not a diy project.

    Bookmark   February 20, 2007 at 8:02AM
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As long as you can get a matching evaporator coil here's the scope of what's involved.

1. Get EPA608 Type II License
2. Close service valve to HP
3. Recover refrigerant from line set and old evap. coil
4. Remove refrigerant lines and remove old coil.
5. Install new coil. Braze or silver solder lineset including a new filter drier. (if you braze you need a low flow of Nitrogen to prevent scale)
6. Pressurise system with Nitrogen and test for leaks. (soap solution). You can also pressurize with a small amount of R22 and Nitrogen and use a Halogen leak detector. (perfectly legal per EPA)
7. Evacuate system down to 500 microns. (or triple evacuate)
8. Charge with refrigerant. You'll need the manufacturers chart or you'll need to recover all the refrigerant and weigh it back in.

I'd guess it would take the better part of a day and you'll need specialty HVAC tools/equipment like gauges/hose sets, Nitrogen bottle + regulator, recovery machine + cylinder, brazing equipment, leak detector, refrigerant and vacuum pump.

Bottom line is that I'd have the tech do it for $1400.

    Bookmark   February 20, 2007 at 10:23AM
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Rock on.

    Bookmark   February 21, 2007 at 9:40PM
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I have a different uptake on the problem. First off the project is not much more difficult than replacing a part of an automotive AC system. Once you remove the gas, and in your case it may be already gone, then it is as simple as cutting the old coil out and resoldering the new coil. The type of solder is silver, so you need at least mapp gas. I like to use an oxy-aceletene torch. When you braze the pipes, it would be best to use nitrogen to purge the system, but if you purged the system several times with F22 you will accomplish the same thing. I prefer F22, but this is what I learned with. Last year I bought a used tank of Nitrogen and guage, so I guess I have come full circle.

Remember, F22 is considered a controlled chemical that requires a license to buy and use. If caught without a CFC certificate and a recovery machine in Texas, you could get a fine and have to stop doing HVAC maintenance. The first offense is a warning most times. You will need a vacuum pump to remove the moisture from the lines once you have brazed the lines. Guages are needed to recharge the system. All of this equipment should cost less than $1000 at pawn shops. If you want to have the tools, this would be a good way to justify the tools purchase. The whole job should be covered with the $1400 price. Kinda dumb for a one time usage, but if you want to learn HVAC this is a way to learn.

EPA CFC certificate test vouchers are available on ebay?

    Bookmark   February 21, 2007 at 11:40PM
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First, is the unit worked several weeks after being recharged, the leak is very small and a tech with proper equipment can locate the leak and repair it. Some flourescent dye can be injected along with freon. The unit can be allowed to operate a few hours and the system scanned with black light and the leak will glow this making it easy to locate and repair. The cost should be a lot under 1400. Call some of the hvac companies listed in you phone directory get a firm quote for this type repair. The easy way for many hvac techs on coil leaks is replace the coil, ma don,t even thimk about a repair. If the repair is properly done the coil eill be as good as new. Good luck Iggie

    Bookmark   February 22, 2007 at 3:23AM
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The cold only cost about $300, so you guy wants to make $1000 for doing it and it should only take him about 2 hours if he's slow. Procedure is as follows.

1. Park any remaing freon in your compressor, basically you shut off the liquid line at the compressor and put guage on the low side, when presure reaches zero, you shut off valve on the low side and cut off compressor immediately (it is best to get help with this so you can have some flip the switch as soon as low side is cut off, ie a few seconds, you don't want to continue running compressor with no gas coming in)
2. Your cut lines leading to evaporator coil with tubing cutter.
3. remove old coil.
4. slide in new coil.
5. braze lines back together
6. without opening the lines back up, pull a vacuum on the side of the compressor shut off valves that is open to the condensor.
7. shut off vaccum and see if vacuum level holds for at least 15 minutes, if it goes up or down, run vacuum pump again, I often just let it run for 2 or 3 hours after I determine there are no leaks in the system.
8. close valve on gauges to vaccum pump so that your systme maintains a vaccumm, open the liquid line first, then the gas line at the compressor. The freon you parked in the compresor is now back in the lines, let it settle for about 10 minutes and restart the system.

You can then charge the system to the appropriate level.

The notion that you have to purge the system of freon to change an evaporator coil is nonsense, nobody does that, the only time you have to purge the system is if you are changing a component, like a drier that is on then compresor side of your shut off valves, since there is no way to isolate the freon.

I hope this helps

    Bookmark   November 27, 2007 at 2:05PM
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((( Acquainted With Islam )))

O Jesus, son of Mary! Is thy Lord able to send down for us a table spread with food from heaven?

    Bookmark   January 11, 2011 at 5:58PM
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I came across this article that might be helpful in answering your question. It really helped me when my A/C broke!

Here is a link that might be useful: Common HVAC Problems

    Bookmark   March 15, 2011 at 6:35PM
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Once the evaporator coil is removed, is there any code or requirement concerning disposing of the old coil?

    Bookmark   April 1, 2011 at 3:56PM
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As long as the coil is free of refrigerant and oil it can be disposed of at the local scrap yard (and you can make a few dollars from the copper & aluminum, too).

    Bookmark   April 27, 2011 at 9:13PM
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how do I figure out part # for my evap coil.. cant seem to find any info on my carrier unit have all the serial & model # but no where on the net can I get the info I need to do a purchase for replacement coil. all responses welcomed and veryu appreciated..TY

    Bookmark   June 19, 2011 at 10:53AM
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So I have a warranty company. They sent out a contractor who wanted to charge me $1300 for my part of replacing the coil (the Warranty company would pay $1100!!). Does that make any sense?

To make it worse, he was trying to tell me that I need to change out the whole A/C ($8000 for a 4 ton Ruud 14 SEER) to that he converts me to 410a.

    Bookmark   June 24, 2011 at 7:03PM
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Not a DIY project.. so many variables. Lots of equipment and skills needed to perform this task. Sounds easy, take the old one out and put the new one in. Even the run of the mill technician taking one short cut could lead to big problems. You need an experienced professional to provide a service that is important to the efficiency and safety of the equipment and your home and family.

    Bookmark   July 2, 2011 at 9:22AM
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Where are all these prices coming from? Our AC died two days ago. I am replacing the AC unit this weekend. I have 3.5 TON unit.
The best quote I got is $2200 for new 3.5 TON unit (converting to 410a), new coil, new pipes (from teh coil to the unit), some duct work, 5 years warranty on the unit and 2 on labor....
I would not pay $1400 for new coil only.

    Bookmark   July 13, 2011 at 11:28AM
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I'm replacing a 9 year old Trane coil tomorrow and the lowest quote came to $1450 for parts and labor (unit is in the attic and not particularly easy to reach). Highest quote was $1690. This is in southeast Texas, for reference.

    Bookmark   July 13, 2011 at 12:54PM
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its a miller a/c 3 ton unit for mobile home.its 4 yrs old and evaporater coil went.a/c guys said it will cost me 600 to install it.its under warranty and coil is covered..since day one i have had this company come 2 times a year to clean it.i have been like loyal to these people.i thought since they were the only people to touch it and they r the original people who installed it i would get a cheaper price..i think its to much money to just install it..maybe im wrong but im going to check around and see about quotes

    Bookmark   August 15, 2011 at 11:02PM
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>>> Our AC died two days ago. I am replacing the AC unit this weekend. I have 3.5 TON unit.
The best quote I got is $2200 for new 3.5 TON unit (converting to 410a), new coil, new pipes (from teh coil to the unit), some duct work, 5 years warranty on the unit and 2 on labor....

Mick: Where do you live? $2200 for a 3.5t unit is a decent price for a low-end system. What brand and model # did they quote? It's hard to compare prices unless you are positive it is apples-apples and then even regional pricing are different (don't ask me how that's fair).

Tarek: The quote above for ~$2400 is around what I was getting quoted this year to replace the coil in my 2.5t gas/electric packaged unit located on the roof. Replacement units ran anywhere from mid $3k to $10k for approximately the same level systems (Ranging from 3-3.5ton, 13-15seer, and 45-70k btuh on heating input).

The Home Warranty can sometimes screw over the homeowner, other times not as bad. Sometimes the contractors are held (read: encouraged) to keep costs very low to keep business coming their way. So they are paid pennies for the covered part of the installation and they must recoup the cost somewhere. So it comes out in higher non-covered charges for installation.

    Bookmark   August 26, 2011 at 3:29AM
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