Trane Home A/C failure (only 4 years old)

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Old 07-26-18, 01:48 PM
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Trane Home A/C failure (only 4 years old)

Hi, We have a Trane A/C unit that provides cooling for our 4 year old home. Trane Model number on Compressor/Condenser Unit is 4TTB6042A1000AA. Unit was new when the house was built and this is its 4th summer. Ran fine throughout June but now, about a week ago, I noticed that it was cooling but that it could not pull the temp down to the normal 74 at which we usually run the house. Now, several days later, it is running and holding the house at say 79 but it will now run throughout the rest of the heat of the day at that temperature. Won't be able to pull it down to even 78.

I've measured the difference between the temperature of the return air and the A/C vent outlet temperature. I have done this several times and typically get a difference of about 8 degrees. Google tells me that should likely be something more like 15-20 degrees.

I have a service call set up but we live out in a small community and nothing happens quickly. So I am just trying to learn as much as I can while waiting.

I've checked around the outdoor unit. Air flow is clear and wide open. The condenser coils look nice and clean though I did not try to wash them off. They look fine. The fan runs. The air coming out the top of the unit is warm to my arm but that, of course, says little. One of the refrigerant lines is coldish to the touch and the other is maybe a tad warm. Haven't been up in the attic where the evaporator lives. Hard to say what I might find up there... The furnace filter is nice and clean. I took out the old one which was only slightly dirty but I went ahead and put in a new one (keeping the old one so I can show it to the repair person coming next week).

Does anyone have anything to share about what would typically be a failure mechanism in a 4 year old system??? Am I only likely looking at a refrigerant leak??? Or might there be something else that is a high failure rate part in these Trane units???

Any feedback would be much appreciated... thanks
 
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Old 07-26-18, 01:55 PM
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Welcome to the forums.

The air being discharged out of the top of the condenser should be pretty hot.
The larger/insulated copper line should be ice cold.

It sounds like you may be low on refrigerant charge.
 
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Old 07-26-18, 03:05 PM
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Thanks for the welcome. First post here.

Low refrigerant would imply a leak, yes?? Is there a “first place” where folks look for leaks?? A place that is most prone to popping a leak?? My fear is the problem might be in the evaporator unit. Which is next to the furnace up in the attic. How do technicians find a leak?? Is there a sniffer or what?? Thanks
 
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Old 07-26-18, 03:51 PM
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Since refrigerant is a gas when it's released..... you can't see anything. You could possibly see some oil sludge in the outside condenser if the leak was out there. A sniffer is used to locate leaks.

Your system is slightly low in four years of service. That would mean a very small and hard to find leak.
The first place they check is connections made during installation as well as leaking service valves.
 
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Old 07-26-18, 04:46 PM
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Yes, sorry for posting that "how to find a leak" question (meaning I don't want to waste your time) cause right after I posted it I remembered the million video clips I could go watch on YouTube. And that's what I've done for the last hour.

The compressor unit is, of course, outside but my big fear is that there might be a leak in the evaporator which is IN THE ATTIC. A lot of the new homes out in this part of California put furnace, blower and evaporator units as horizontal installs in the attic.

We bought this home new in a large retirement community and watched it get built. I remembered being shown the large access port in the laundry room (and the house has 10 foot ceilings) and I wondered how hard it must be to move a furnace unit down and back up through that hole if it had to be replaced... But I was comforted by the knowledge that it was a new home with a new 100,000 BTU furnace so what could go wrong... Turns out, plenty. Six months after we moved in and of course in the dead of winter, the furnace failed. After a month of diagnostics and some cold nights, I got to watch (and I helped) as they lowered a 140 pound unit down through that hole that would never get used (or not soon anyway) and watched as they raised a new one up through the hole with ROPES. I was stunned that this large company did NOT have a little mechanical lift they could roll in from the garage and lift something like that up through the hole. So that was nightmare 1.

Now, I am fearful the problem might again be in the attic, in the evaporator. And that that, too, might have to get replaced. I am using a small company this time who came highly recommended but they couldn't come out until next Monday so I'm using the time in between to try to learn more about A/C units.

Do you have any experience on how often leaks are found on the outside unit versus in the evaporator??? is it 50/50?? 90/10?? And please say 90/10 outside unit / indoor unit???

And oh my, how often do you find in leak in the lines going up inside the wall that gets the two refrigerant lines up to the attic??? OH MY!!!! Please not that...

Any comments on most likely location??? Inside??? Outdoors??
 
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Old 07-26-18, 05:38 PM
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Some good news..... since it uses R410A..... you won't pay sky high prices for refrigerant.
You could have it topped off now and a leak found/repaired at the end of the season.

I believe your system has a 10 year parts only warranty.

Very unlikely that the lineset is leaking in the wall.
 
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Old 07-26-18, 05:55 PM
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Thanks Pete, I was just going to start looking up what refrigerant my system uses. But you say R410A. It seems like it's either that or the older R22 if I recall??? And R22 is worse for the environment so it' been or is being phased out for R410A??? Is any of that correct??? Is that how you knew I had R410A, because it's 4 years old??? I looked and the unit was built in January, 2014.

And is it possible that this system has had a tiny leak for 4 years but it takes a long time for it to leak down to where it causes notable systems??? This happened pretty suddenly. Worked fine for four summers, 2014 - 2017 and through June of this year. I could set it at 74 and it would just go there.. Now, it couldn't ever get the house colder than say 72. That was like the limit during the heat of the day but 74 was easy to hit and it would shut off for a while. Then a week plus ago, I just noticed one day when I had it set at 75 it sat at 76 ALL DAY. That was my first clue and now today it is calling for 78 and it won't get lower than 79 (but it is way hot outside).

Livable but broken...

thoughts???

thanks... bob
 
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Old 07-26-18, 06:29 PM
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R22 was phased out the beginning of 2010 so it has to be R410A
 
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Old 07-26-18, 11:08 PM
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I didn't ask but I'm assuming the filter(s) have been changed.
 
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Old 07-27-18, 04:39 AM
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Having had less than stellar experiences with service techs I bought one of these. Some techs will only put refrigerant in and not look for leaks. Being inquisitive you might enjoy it. Very cheap but has good ratings and I have found 2 leaks with mine. The battery compartment door falls off but for occasional use no big deal.

https://www.amazon.com/WJL-6000-Port...+leak+detector
 
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Old 07-27-18, 05:31 AM
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Yes, filters are changed but I do have a point to make about that. This house has two main filters for the main A/C and Furnace, a large 20 x 30 in the hallway that pulls a huge amount of air and then a smaller one in the Master Bedroom. Both originally came with a fancy, pleated filter, the ones you pay $20 or so for at the box stores. The one in the Master Bedroom seems to pull little if almost any air and has never been replaced. Looks like brand new. I just checked it again the other day. But the main one in the hallway, when the furnace failed back in 2014, I had noticed many times before that the system pulled out that large, pleated filter so hard that it would bend, almost like the system was about to bend it in half and pull it in to the duct. Three technicians, supposedly the A-Team for this furnace company that came out to install the new furnace and hook it up all told me to STOP using those thicker, more plush filters and to instead just use the inexpensive fiberglass ones which is what I have done since. I still have several of the pleated filters, unused out in the garage because I had bought spares when we first move in.

But do you have an opinion about whether you agree that these cheap, green fiberglass filters stop enough stuff or might I have pulled in a lot of dirt and maybe that's an issue??? I took out the green filter just last week and replaced it. I kept the one I took out to show to the guy next week and it was a tad dirty but nothing terrible. I went ahead and changed it anyway.

One other point it this home has a whole home ventilation system that just runs the blower motor to push air around the house from a port that opens on the roof when you turn that system on. A way of bringing in fresh air. We chose long ago not to run it much as it runs at an incredible 50% duty cycle, meaning on almost all the time. But I've wondered if maybe the roof door might be stuck open and if so that would mean we would be pulling in hot outdoor air. There is a third, small filter inside the box of the main filter that sits in front of the duct that goes up to the roof. Not sure how to test to be sure that roof shutter is closed and not even exactly sure where that roof door is, on the roof, lower, what??? Just another point.. That filter also never gets dirty in large part cause we don't run that system. And it's not getting dirty now so hopefully that is one clue that the roof door is NOT open.

So your comments on using the thinner fiberglass filters???
 
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Old 07-27-18, 05:36 AM
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Oh wow, I figured on of these detectors would be 100's of dollars... Do they work??? thanks much for offering that input...
 
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