Leaky AC System ???


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Old 05-11-09, 04:58 PM
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Leaky AC System ???

Here goes...

Moved into a newly built house in October 05. (It was the fall so did not use the air condition unit) In June 06 notice the downstair unit was not cooling properly. Contacted the sub-contractor who put the unit in and they came out and stated that one of their technicians when installing the unit did not tighten the outside valve properly and the freon leak out. The contractor refilled the unit and the unit began to cool properly.

Then in May 08 (2 Years later) the unit again was not cooling again as it should. Contacted the sub-contractor again and they refilled the unit and they stated that this time it was due to a leaky condesor unit. I was skeptical that if indeed the condensor coil was leaky that maybe they mis-diagonosed the unit the first time in June 06 and that the coil condensor should have been covered fully for part and labor and now the parts are only covered. Of course they disagreed.

The technicain sent was honest and stated that the unit once filled would last probably another 2 years until the freon completely leaked out. Similiar to the time between 2006 and 2008. Once the unit was filled the unit began cooling again properly.

Now I have brought another contractor out to get unit fixed through my home warranty (Hopefully for good) The new contractor now says that it is not a condensor issue but the evaporator coil is leaky. They state that this was a known design flaw due galvanic corrosion between the coil tubing and plate that was solved by the maker of the evaportor by tin plating both materials. When I asked why I was initially told it was the condensor, I was told that most likely the person did not want to get up into my hot attic to verify the real problem and it was easier just to tell me that it was the condensor.

I have no issue with replacing the evaporator if this is the issue but how can I be sure? The last thing I want is to have the evaporator replaced and then I lose freon again and find out it is the condensor or something else.

Also, the one thing I do not understand is the technician when checking the unit this last time stated that the freon charge was still good. I told him that it was filled a year prior. But I am still seeing a difference between the air temperature of the registers down stairs and upstairs. Upstairs the air registers are running about 13 to 14 C (55 - 57 F)where as down stairs are running 18 to 19 C.(64-66) Ambient temperature was about 24 C (75 F) at both intake registers. Even if I have a leaky evaporator, as long as I currently have enough freon would I expect that much of a difference?

I went into the attach with a tempeture gun and do see a different between the 2 units. (based on air temp leaking out where the liquid and gas line enter the units) Additionally, I noticed the low pressure gas line into the outside unit feels not as cool as the the other unit. But I also noticed that the insulation on the "troublesome" unit is not total surrounding the tube. Could the temperature of the output air be effected 6 degree C just due to this improper insulation?

Finally, to replace the evaporator coil, the new contactors states he can not warranty his work unless I also pay for a new drip pan and float switch So to have the unit replace it will cost $585. This would be for a drip pan, float switch, pump ups, permit fee. He says I can keep the current float switch and pan but if I do and there is leak don't come running to him.

It was going to be $960 but I got my warranty company to cover any duct modifications ($225) and reclaim of the freon in the unit.($125)

Any words of wisdom will be highly appreciated.
 
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Old 05-11-09, 05:09 PM
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Coil will come with a new pan so that was a lie. Float switch can be tested. I would not trust any thing that comes out of a home warranty contractor. 2nd if you don't trust the 1st guy spend the money for a GOOD HVAC company to come out. This will be around $100.00
 
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Old 05-11-09, 05:41 PM
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I'll ask about the pan tomorrow. The warranty company chose the contractor. I did not have a choice.

I agree with spending the money on a "good" HVAC company. The problem is I have spoken with a few people and no one can give me any recommendations. Any suggestions on how to determine someone who is good versus someone who is just trying to make a buck.
 
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Old 05-11-09, 06:54 PM
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Look for company's that have been in business for many years. Look for company's that don't pay their tech for sales. Look for company's that sell name brand equipment.
 
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Old 05-12-09, 03:02 AM
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If I'd have gotten as much runaround as you have I'd ask the tech to SHOW ME the leak. I also agree on getting a reliable firm out there, warranty or not. I also have a problem with the unit leaking and yet still has sufficient charge.
 
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Old 05-12-09, 05:58 PM
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I went up in the attic and he used the sniffer and it went off but I figure that there is a way to make it go off even if there isn't a leak.

Obviously, I am pretty cynical.
 
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Old 05-12-09, 06:19 PM
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I agree with you, but I guess I'd give him the benefit of the doubt.
 
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Old 05-15-09, 06:14 PM
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I appreciate all the input. But does any have any idea based on my AC symptoms if it sounds like a leaky evaportor issue.
 
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Old 05-15-09, 11:12 PM
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Yes, it sounds like the system has a slow leak, as proved by the warmer copper tubing and the warmer air temp. Are you showing any frost on the tubing where it enters the evap coil? That would be another sign of loss of freon. Could be anywhere but since the sniffer went off up around the evap coil, that's probably your best bet.
 
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Old 05-15-09, 11:28 PM
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What duct modifications? You open the cabinet, remove the old coil, insert the new one and bidda bing. Drip pan? What does he mean? The secondary drip pan under the unit is too small? Or the "duct modifications " will render it too small? It sounds like he talking about installing a cased coil. Translation- the new cooling coil will come with a new housing or cabinet that it goes in. What brand is your unit?
 
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Old 05-16-09, 02:10 PM
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There is no frost at the Evaporator coil but when I last check it showed only little off from full. My drip the fits the length of the coil/air handler looks like it has not had any water or very little ever in it.

When I spoke to the HVAC, he said that until getting the coil that he wouldn't know if needed any duct work modifications. I told him thought I figured that it would be a plug and play replacement unit. He stated not necessarily.

When his technician was out he said that it would take an hour to replace. Pull the old one out, put the new one in and recharge. When I told his manager what his technician stated, he said he wished his technicians wouldn't say things like that because until they get the coil he doesn't know what needs to be changed.

As for the unit, it is a HEIL 12 Seer unit. The technician made it sound that this galvanic rust issue has been a known issue But I am not sure what to believe anymore.

He also stated that just wait because the second coil would not be far behind.

I have spoke to a few people and gotten some reference for some reputable HVAC businesses. If I begin to have problems with the second unit, I will not be going through the warranty company again. With that said, can anyone give me an estimate on what it would cost to replace a evaporator coil normally. When I talked to the current contractor assigned by the warranty company they stated about $1800 dollars to replace. $900 dollars of it being the evaporator coil itself.


Thanks for all your comments.
 
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Old 05-16-09, 04:54 PM
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Wow I think I'm going to come out of retirement. I agree with the person you spoke to that they should select the replacement coil first before before quoting ductwork mods, new drip pans etc. One hour to change out a coil? In an attic? I don't think so. Involved is refrigerant recovery, changing out the coil, leak testing the new piping connections, new filter drier, evacuation to 500 microns, blank off test, recharge with new refrigernt, monitor operation, clean up. That's how I would do it. Anything less is corner cutting, especially at those prices. If there are any other leaks, the evacuation will not hold. That's what the blank off test is for. You let the system sit for a while to see if it holds the vacuum.
As for the corrosion, it's industrywide not just your brand.
Check the pirces at this link Goodman Air Conditioners, Heat Pumps Direct from ACWholesalers.com and SAVE! Free Shipping.

Not your brand but it will give you an idea. Look at the list prices which would be retail. Heil is made by International Comfort Products Co. They have several brand names which are all pretty much the same unit. There should be no problem with getting a replacement coil from ICP for a bidda bing swapout. There are also several companies that make aftermarket replacement coils.

Frankly, I think you need a third opinion. Make them show you the leak.
 
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Old 05-16-09, 06:13 PM
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I sure appreciate all the information.

I did go up with the technician during there last visit and he used the sniffer which went off twice. He stated that there was 2 small leaks.

The problem is the more I learn, the more skeptical/paranoid I am with the whole diagnosis.

I am thinking about telling the technician when the come out to replace the evaporator core that I am one of those guys that really likes to know how things work and set up a video camera in th attic and tape the whole process.

At least it may deter someone from cutting corners.

Maybe you should come out of retirement. Interested to coming to South Carolina and looking at a A/C system.
 
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Old 05-16-09, 09:08 PM
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At those prices it's tempting. With the cover off of the evaporator section of the air handler, the tech should be able to go right to the leaks on the cooling coil. You might take the cover off yourself and see if there is any oil on the cooling coil. Look all over with a bright light but especially around the drain pan area. I'm not against anyone making a good living and a profit, its expensive to operate a business. I also realize that the economy is in a dump now and it's tough out there. But, there's a good living and then there is gouging people and corner cutting which I can't stand- especially the corner cutting. Folks should expect to have to pony up some for quality repairs but not get legally robbed.
 
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Old 05-26-09, 06:18 AM
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daddyjohn-

Took your advice and getting a second opinion. I have spoke with a friend who is a long time contractor, he recommended a family own operation that he states is trust worthy. I check there credentials on BBB and were A+ rated.

They are coming out today to take a look so I can see if they come to the same conclusions. If they do then I'll way the cost between the two companies to fix it. If the cost are close (between 10 - 20%) I'll probably have the recommended company perform the work instead I have to worry about shotty work from the other company.

I agree with legal robbery. I am a Quality Engineer by profession and I have no issue with paying for high quality work. I am the type of person who will pay 20% more for something if I am confident with the work.

I'll let you know the outcome.
 
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Old 05-26-09, 06:48 PM
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So here is the update, the 3rd HVAC company came out today to diagnose the problem.

But let’s recap. 1st HVAC company stated the coil condenser was leaking. The 2nd HVAC company stated the evaporator was leaking.

The 3rd HVAC company couldn’t find a leak in either coil.

The 3rd HVAC did the following to try to find out what is going on:

1)Check temperature in all down stair vents, versus return air and at the thermostat. (Thermostat and Return air was around 77 F. – Vent Air was around 68 F )

2)Check the return air filter. (Stated that due to the size of the return air duct that he would recommend a different filter because the current filter was putting to much drag on the system)

3)Check the freon pressure outside. (Running at 68 PSI, Initially stated that anything above 60 can be ok but need to look at the rating on the evaporator coil)

4)Check the evaporator coil for leaks. Did not find any leak but did comment that the unit in the attic was not sealed very good.

5)Resealed the unit to see if that would bring the vent temperature down. (Did not help)

6)When back outside and check the pressure and this time check the temperature of the low pressure return line. (Pressure still at 68 PSI and temperature around 78 F degrees) Stated that there should be a 12 degree difference between the coil and the outside line. Coil should be 48 degrees meaning the outside should be around 60 degrees (Also commented that the line outside had no condensation on which it should have some due to the temperature outside.)

7)Charged the unit to 80 PSI to get the outside line to come down about 66 F

8) Recheck the vents inside and the had come down to from 68 to 62 F.

9) Verified the condenser with sniffer and visually inspected. No Leak found. (It was commented that usually you would see oil on the condenser coil or “wet” spot where debris would collect on the fins) No issue found.


So after all that, it was decided that based on my previous description of out of freon in 2 years, that the leak is small and the most likely culprit would be the evaporator and should probably should go ahead an replace it while it is still under warranty.

I believe this is what they will do in replacing it.

1)Pump the current freon charge down into the compressor

2)Remove the old unit

3)Install the new unit (Braze Joints, reconnect PVC)

4)Leak test with nitrogen

5)New line dryer

6)Evacuate system

7)Verify everything is O.K

8)Recharge/ Re-pump system

9)Reseal unit.

Their price $400 not including the $166 I paid for the service call: Service call Breakdown as follows:

1)Service call $79 for standard diagnosis

2)$55 for Leak investigation (Labor) – beyond standard diagnosis.

3)$32 for 1lb of freon


I called around to 6 other places asked what to replace a under warranty evaporator coil and got ranges from $250 - $850. So I thought that was at least on par. And from there work today thought that they were at least pretty thorough in there investigation.

The last thing that service technician stated that since it seems to be such a small leak that the worst case is that it is not either coil but that a line that was nicked during construction. He said that the only way to know that is to isolate both compressor / condenser and evaporator and charge both of them with nitrogen to see which one it is. He stated that once you start doing all that the cost for labor, etc become more than just replacing the units under warranty. He stated that if it is a small pin hole leak in a pipe, that he would recommend servicing the unit every 6 months to a year and paying $16 for a lb of freon (Service contract discount on freon).


Let me know anyone thoughts.
 
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Old 05-26-09, 07:23 PM
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So since May 2008 it only needed 1 lb. of refrigerant? Usually with an evaorator coil leak the refrigerant leaks out quite fast. I see two problems. If they change out the evaporator coil in warranty and the manufacturer tests it and says its not leaking, the contractor will have to eat it. They're taking a chance. The other problem with that is if the leak is in fact in the interconnecting tubing and not the coil, they'll never get a good evacuation. Separating the system into components and nitrogen testing is a good idea. The problem is the leak is so small that the results will probably be inconclusive in the short term. It does sound like the 3rd guy was a lot better. Frankly if the leak is that small, just add refrigerant as needed. If you're really determned to get the leak fixed, let the system sit with nitrogen in it over the Winter and in the Spring see which section leaked out. Just make sure the cooling control circuit is disabled. Turning the system on with nitrogen in it will damage it.
 
 

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