Time for a new "service" company! Can't speak to the issues with the coil (they are frequently manufacturing defect issues) but the thermostat should be an easy fix for someone who knows what they are doing.

I am on the third service company. I used the original installers for service for the first 5 or 6 years. But when they could not solve the humidity issue after several tries, I moved on to #2. Same story there. Now, #3 has gone over all the major components (and checked wiring at my request). They also replaced all refrigerant, installed a new drier, and then determined the TXV needed to be replaced, which they did last week (all under warranty). The system cools just fine. It will maintain the temp I set. However, the humidity ranges from 54% to 61%, or higher. I know the system is capable of pulling the moisture out of the air because yesterday I dropped the set temperature to 70 degrees as a test, and within about 25 minutes it had dropped the humidity from 58% down to 48%. That is why I maintain the problem is with the T-stat and/or dip switch settings. The set-up combination is not correct to tell either the small compressor or the large one when to keep running.

There are a lot of options to set between the thermostat and the air handler control board. Let's check to see how the thermostat is set up first.

What is the setting for System Type Selection (0170)? Is should be either set to 11 or 12 according the to the 802 thermostat installer manual.

What is the setting for Indoor Dehumidification Control (0380)? The factory setting is "0" which means off. If it is, then set it to "1" and see if you can better humidity control.

How large is your house and do you have a lot of south facing windows? You have a 5 ton heat pump which may be too big to give good humidity control. I realize it is a 2-stage heat pump, but I am sure you get many days of high humidity with mild temperatures. The heat pump could probably run in the low stage most of the time.

The fact that the Y and YLo wires were swapped may give a clue as to how the old system worked so well. If the original air handler was set up to do the staging, then swapped wires could have caused the heat pump to first run on the high stage, and then transition to the low stage for an extended period of time. This could give better humidity under some conditions. You may have had a situation where a bad installation may have compensated for over sized equipment. This is just a theory, but something to consider.

Thanks for your response, Mike. The fact that you know of those t-stat setting numbers indicates you have some direct knowledge of this particular set-up.

As to setting 0170, I have tried both 11 and 12 (note - mine is an 803 t-stat). The same goes for 0380 - I have tried both 0 and 1. I had always left 0380 on 1, with the humidity target of 50%. I could walk past the t-stat any time of day or night and the temp would be exactly where I had set it (usually 78 or 79 degrees), and the humidity would be at 50%.

My house is 2,670 sq ft, with only 2 south-facing windows (one is a small bathroom window, well removed from the t-stat). Also, just to clarify, when this system was installed in 2008, it was a complete package - new compressor unit, air handler and t-stat. As I originally stated, it worked beautifully for almost 6 years, until the first evaporator coil developed a leak. It has not controlled the humidity since then.

Are you suggesting the reversed Y and YLo wires may actually have been that way from the time of the original installation? I suppose that is possible, but I have always assumed they were switched by mistake when the evap coil was changed in 2014.

Are you familiar with the 8 dip switches in the air handler? I have tried numerous different combinations with those. Some do better than others, but I clearly have not yet found the right one.

Thanks for any thoughts you might have.

I do think it is possible that your original air handler was not installed properly. But we will never know for sure.

I have found two installation manuals. Here are some links:

Trane Modular Variable Speed Air Handlers

Installer's Guide - Convertible Speed Air Handlers 21/2 - 5 Ton

DIP switches 1-4 control the cooling air speed, switches 5-6 control the fan off delay, and switches 7-8 control the auxiliary heat speed.

The document stages your air handler (2TEE3F65A1000A) had the switches 1-4 set to all off at the factory. It is set to 400 CFM per ton of air flow. If you look at page 14 of the first document, you could lower the speed to 350 CFM by changing switch 4 to on. You could try that if it is not already set.

Switches 5 and 6 are interesting. If you look at page 10 of the second document there are four possible settings. There is an enhanced setting where switches 5 and 6 are both on. There is a diagram showing how the speed slowly ramps up and down. I am not a Trane expert, but this may be the Comfort-R setting. It may give give you better humidity control.

Don't forget to shut off the power before changing any switches. Take a photo before in case you need to undo any setting. I suggest making one change and then run the handler for a while to see if it makes an improvement before changing anything else.

Thanks, Mike. I had this same info in documents I have found on the internet, but in a slightly different form. Unfortunately, because the installer did not record the settings for the t-stat or dip switches, I have no idea what the settings were when the system worked so well. I have tried using the factory defaults, but to no avail. Now it's just a matter of trial-and-error in my endeavor to remove humidity from the air.

Getting back to the t-stat setting 0170 for a minute, I have always been curious about the classification of my system. Does the fact that it has two compressors and electric strip "emergency" heat mean it is a 2 Cool / 3 Heat system, or do the two compressors count as one source of cool and heat (i.e., 1 Cool / 2 Heat)? Or, does the "emergency" heat even factor into the equation (1 or 2 Cool / 1 or 2 Heat)?

The XL19i is a 2-stage condenser. That means you have 2 cool and 2 heat stages. If you have auxiliary heat strips, which are probably unnecessary in Orlando, then you have a 2 cool / 3 heat systems.

You are like me in that you are comfortable with the temperature at 78-79 degrees with a humidity of 50%. That is what I typically do in my house in NJ. The best way to achieve that is to keep the heat pump in the low stage for long periods of time.

What could be happening is the new thermostat and air handler combination is running in the high stage more often than your original equipment. Are you able to tell when the heat pump is in the low and high stages? Does the heat pump run for short periods of time? Did anyone do a load calculation back in 2008? How was the 5 ton size determined? Was it based on the size of the previous equipment?

I can hear the difference between the low and high stages if I am near the window that is close to the condenser unit (or if I am outside near the unit). I have not made a record of which stage runs for what amount of time because I keep trying different switch settings to see which ones will lower humidity. I don't have the t-stat settings in front of me, but I know there are two (0220 & 0230 perhaps?) that control the number of cooling cycles per hour. Would that be a way to force the low stage to run more? The factory setting is 3 cph for each. Should I make one of them 1 and the other 6, or do they both need to have the same number of cph?

I do not recall there being a load calc done in 2008, but I did get estimates from 3 contractors, and I believe all were recommending comparable size units. Most likely, the 5 ton size was simply based on the unit that had just died.

I really don't think the unit is over-sized (at least not significantly) because of how well it worked for the first 6 years. Also, just to be clear, this is still the original 2008 Trane air handler. Only the evaporator coil inside it has been replaced, twice, due to leaks.

This may just as much boil down to a really humid year, because I can tell you a cool setting of 78-79 is not goint to dehumidfy under certain conditions of Florida weather. You have to realize that humidity and temperature are independant of one another. BUT, your thermostat -- any thermostat in regards to humidity control will limit that control to with in 3 degrees of cooling temperature. REGARDLESS of how humid it is in the home.

This trips up many people looking at the humidity readings of the stat and saying well I have my setting set for 50% humidity and it's reading 65% in here. Something is wrong.

Not necessarily. With a temp setting of 78-79 --- at 78 setting the system runs more or less in dehumidification function and will cool to an additional 3 degrees beyond that 78 degree setting and shut off at 75 regardless of whether your humidity setting is reached or not.

Because you have a 2 stage condenser you have a much better chance of hitting your dehumidification setting because in dehumidification mode the smaller of the two compressors will run and due to that it will run much longer.

So with that said, I would check to see that it is the small compressor running when in dehumidification mode. I think it probably is because other wise you would be having cooling problems when it's really hot out.

Remember, you can get more dehumidification out of your system by adjusting your temperature settings. Those temperature settings whatever they are will directly effect how much dehumidification you receive. It's only a 3 degree band from your temperature setting.

It's October right now... humidity can keep coming in a tropical climate even as temperatures drift off. So you have to adjust your temperature settings.

I just reread something you wrote about it reading exactly how you had it set at 78-79. Under that you have no dehumidification. Dehumidification will dehumidify 3 degrees below what ever the temperature is set to.

Normally thermostats have only one cycle per hour settings. This one can control the number of cycles by stages. I suggest you leave 0220 (low stage) at 3 cph, and decrease 0230 (high stage) to 2. You don't want to encourage more low stage cycles, but you do want to decrease the number of high stage cycles.

Do you have temperature and humidity gauge? If not them an inexpensive one on Amazon. You need to verify the readings on the thermostat are accurate.

Does the thermostat ever drop below the set temperature. As Ray mentioned above the thermostat is supposed to over cool by up to 3 degrees if the humidity is too high. If it is not doing that then something is not right.

Have there been any changes in the house that may be letting in more humidity from the outside? Anything that reduces outside air infiltration will help with humidity control.

Do you ever leave the house for long periods of time? If so then consider setting back the temperature to 82 degrees, or 3 degrees higher than you normally set it at. The heat pump will have a long run time during the recovery period. This will give it more time to dry out the air. You can decide whether you want to turn off the 0530 (adaptive intelligent recovery). I have it turned off on my thermostats since I want the maximum set back period for heating and cooling.

I am familiar with the 3 degree over-shoot when the system is trying to achieve the desired humidity setting (when "humidity priority" is selected in 0380). However, I believe that over-shoot only occurs if the system cannot reach the set humidity while also maintaining the set temp. In other words, simply setting 0380 at 1 does not require the system to go 3 degrees below the set temp, but rather allows it to do so if it cannot otherwise reach the desired humidity setting. This may all be as simple as the theory posed yesterday by Mike - that the Y and YLo wires were indeed reversed at the time of initial installation, thereby causing the larger compressor to run most of the time. I presume this would result in greater cooling of the refrigerant. Further, if that were the case, and the t-stat was calling for low fan speed, "thinking" it was running the smaller compressor, might that have yielded lower humidity without necessarily pulling the temp down lower than the setting?

"The system will generally stay close to the set temperature, but the humidity is usually anywhere from 55% to 63%, though sometimes it will run it down as low as 42%."

"Only the evaporator coil inside it has been replaced, twice, due to leaks."

"installed a new drier, and then determined the TXV needed to be replaced, which they did last week"

Why did the installer have to replace the coil twice? Then they replaced the drier and TXV. Maybe this is not a setting issue but an installation problem.

I would think most of your original thermostat and DIP switch settings were the factory defaults. The only thermostat setting you must set correctly is the system type. You can get away with not changing anything else. So maybe there are problems beyond settings. Changing one or more settings may improve the performance.

I understand your frustration in that you had a system which had good humidity control for 6 years. Something has changed and I don't think it is just a settings issue.

Sorry, Mike, this story could fill a book. In my attempt to keep it as short as possible I did not make clear the timing of the coil and t-stat replacements. The system was installed new in September, 2008. In 2014, I had cooling problems, and the evaporator coil was found to be leaking. It was replaced, along with the t-stat (because the face would no longer light when touched). The system cooled, but humidity was never good after that. I had several unsuccessful HVAC visits over the next couple of years. Then, in March, 2017, the 2nd evap coil developed a leak, and was replaced. Again, I had cooling but poor humidity control. Thinking that the replacement t-stat was the issue, it was replaced with stat #3 in September, 2017. That brings us to August, 2018, when my warranty was about to expire. I scheduled a system check to make sure there were no leaks. If there were one, I wanted it covered by warranty. The tech said there were no leaks, but determined the TXV was not functioning correctly, so he replaced it. I had high hopes that would solve the humidity issue, but it has not. Because all components appear to be working, and refrigerant level (I am told) is correct, I have to believe the humidity problem lies in the t-stat and dip switch settings. I just need to find the right combination. Or maybe swap the Y and YLo wires again!

I think swapping Y and YLo is going to make the humidity situation worse, especially during the cooler time of the year.

Does your duct work run through the attic or some other unconditioned space? If it does then you may have leakage in your return that is pulling in humid air. That would make it more difficult for the system to control the humidity. It may also explain there are periods of time when you do get better humidity control.

However, I believe that over-shoot only occurs if the system cannot reach the set humidity while also maintaining the set temp. In other words, simply setting 0380 at 1 does not require the system to go 3 degrees below the set temp, but rather allows it to do so if it cannot otherwise reach the desired humidity setting.

Correct, but in a high humid climate like mine as well as yours it will almost always run to 3 degrees below set point temp, if it is not doing this humidity readings will be much higher. That is proper operation. That setting can be adjust from 1 to 3 degrees.

When your system starts up from a stop, it will enter first stage or low stage cooling. This is more or less dehumidification mode. If your dehumidification is shut off (meaning the 1-3 degree drop in not in play) the system I believe will behave differently. Because your system handles the call it is meant to perform and that is to 'cool' to your temp setting.

If it runs in 1st stage low cool for 5 min or whatever it is and doesn't settle the call to cool, it switches to stage 2. This will over cool to drop temp to thermostat set point and finish the call.

When your system enters 2nd stage, it's more about finishing the call as opposed to dehumidifying. An air conditioner is more or less dehumidifying as long as it's running, but it is much better at this job of dehumidification when it's not 'over cooling' merely to reach set point of the thermostat.

This is why you need to allow the system to dehumidify via the 1-3 degree band, because of your climate I would use the 3 degree setting. The system can not dehumidify unless it is running and dehumidification is separate from that of cooling to desired temperature set point.

Often times the humidity set point is never reached in a high humid climate. Especially if your setting is low like 40%. It all depends on what is happening outdoors. If the humidity outdoors is 80 - 90% you may not get your setting to even hit 50% in a high humid climate like ours.

Humidity is always changing outdoors. Sometimes it's less sometimes it's more. Outdoor weather has a direct influence on your HVAC system and how well it performs.

I had the A/C tech back yesterday for the 5th time in as many weeks. He verified all pressures were good, and checked all the settings and switches. Then, he called Trane and spent quite a bit of time on the phone with them. He told them of my humidity issue and all he had done in an attempt to resolve it, including the replacement of the TXV last week. The Trane rep told the tech to relocate the TXV bulb to outside the air handler. (The bulb had been wrapped to the large copper cooling tube that goes to the eval coil, inside the air handler case, right next to the coil.) The bulb has now been put inside the insulation that covers that same large tube before it enters the air handler case. The Trane rep also said to set dip switches 4, 5 & 6 to "ON". This is the 350 CFM/ton fan speed, with "Enhanced Mode" on. With the relocation of the TXV bulb, the superheat dropped from 25 to 21, which the tech said would help with humidity control. After a day and a half, the temp is holding at 78 degrees, and humidity has been 50 - 51%. I am hopeful this has finally solved my 4-year humidity problem. Time will tell.

I truly appreciate all the helpful advice and suggestions Mike and Ray have offered. I am under no delusion that I can perform A/C service or repair, but I can do some basic work like wiring a thermostat and changing some settings and switches. Basically, I know just enough to be scary. But, in the words of Clint Eastwood's character, Dirty Harry, "a man's gotta know his limitations." The really frustrating part of this whole situation is that I have called Trane myself a couple of times over the years, and tried to get them to let me speak with one of their tech people. Instead, they said I had to call one of the authorized Trane service companies in my area. All three of the HVAC service companies I have used are "Trane authorized," yet it took me becoming a pain in the ass to this third service company to finally get results.

Thanks again, guys!

If what they did --- did any good, it is my opinion that the stars happened to align and humidity outside dropped in your area. It's Mid October here and there's been a few days last week where humidity dropped for almost an entire week below 50% outside. BUT, this next week it's supposed to do nothing but rain, so that didn't last long.

Your humidity control is that smaller compressor in your outdoor condenser. If he isn't running... you don't have any 'real' humidity control. Give him an additional 3 degree band in which to run and you increase his capability further.

I am not sure what effect relocating the TXV does on the humidity performance. But if the Trane technical expert said to move it then I suppose there is a reason.

Changing switches 4,5, and 6 to the on position is makes sense. Lower air flow will help dehumidify, and the enhanced mode is supposed to keep the air handler in the low stage for a longer period of time. The strange part of all this is why did these dip switches have to be changed? Could they have been set this way originally and changed when the new coil was installed?

You would think an authorized Trane dealer would know the best position of DIP switches for the local climate. It comes down the knowledge of the technician that comes to your house. Most people will set there thermostat at 75 degrees. But you are like me in that we are comfortable at 78 degrees and 50% humidity. Most likely the factor defaults work for most people and this is why techs don't know what to do in situations like yours.

Ray is skeptical that your humidity performance will improve. Keep up us updated on the performance. There is a lot a good information for people who want good humidity control at a higher than typical indoor temperature.

Apparently, the bulb part of the TXV determines how much refrigerant is allowed through the valve part of the TXV. (Forgive my layman's understanding of this whole process.) So, even though the bulb was well wrapped to the large refrigerant tube inside the air handler, the Trane tech felt the bulb could be influenced by any small amount of cold air that might be drawn across it. Therefore, putting it outside the air handler (but still against the same large tube) allows it to function as intended. I will definitely keep an eye on it.

Nearly every manufacture that make evap coils these days including Trane, when they include the TXV with the coil it's mounted to inside the coil box, it doesn't come separately. So it sounds like more chasing your tail than anything else.

If humidity control was that simple (in a high humid climate mind you), you wouldn't be on a forum board looking for answers.

Air flow does play a part, however the single most important thing is run time of the AC you have a 1st stage compressor and a 2nd stage compressor.

The longer that 1st stage compressor runs the better your chances as I said before this requires the use of the 3 degree temp band setting with in the thermostat. If the thermostat doesn't have this functionality you don't have any 'real' dehumidification outside of normal over cooling of the AC unit. Which is more about temperature control than humidity, if that's the case.

I hear what you're saying, and it makes no sense to me why the bulb would suddenly need to be outside the box. As I keep going back to, the system worked fine for many years with the original bulb inside the box. In any case, the 1st stage compressor is running more now, and humidity is staying low. Perhaps the tech found some other basic wiring screw-up someone else did years ago, and he didn't want to admit he had overlooked it. Who knows? For now, I am happy. Thanks again!

I've seen more failures of the TXV itself with them inside the coil box, but I think these failures are more often over heating of the valve when brazing the connections at the coil than anything else.

I've seen some bulbs that had been flapping in the wind of the attic (installed by other companies) that had been operated this way for years until I happen to get called out.

Then I tell the people how wrong it is and they say 'it's been that way for years and works perfectly fine...' Well I am not going to be a part of your 'Tom Foolery'... I'm only here to do this professionally.

BUT....To move the TXV from outside the box to inside the box or vice versa really isn't a cure for performance in my opinion. As long as it's not over heated during brazing and the proper methods are performed to charge the system adequately it's more a matter of ease in which to service it and or replace it when it does eventually fail... hopefully from natural life causes.

It's mid October so you may not truly know it's been fixed until the flare of the flaming rock in the sky makes it's rounds next year.

Mike. None of the companys and people in this forum seem knowlageable. Hows the rh 3 yrs later?

Hi John,

My AC continues to do a good job maintaining the humidity. Today the outdoor humidity hit 90% with temperatures over 90 degrees. Indoors the humidity level is about 40% with the downstairs thermostat set at 78 degrees.

I am not sure what effect relocating the TXV does on the humidity performance. But if the Trane technical expert said to move it then I suppose there is a reason.

None. Just makes it easier to replace again later when it fails again. Tranes seem to be notorius for TXV failures among other problems.

These parts used to be only made in USA, I was lucky to see one fail on older equip in 15 years. Now they are made else where and failures are as common as apple pie. (That's assuming you can even find the part now circa 2022)

If I come to a system, I much more prefer that the TXV is outside the E-coil cabinet. If it's 95 outside it could be 130F or more in that attic. That's the only reason why. I've never found any one willing to follow me and stay up there watching me fix things like that. (easy bake oven)

If the TXV fails the cooling performance will be noticed much sooner in elevated outdoor temps. The rooms farthest away from the indoor equipment will feel it first. (capacity issue)

I service the Katy, Texas area.

"None of the companys and people in this forum seem knowlageable."

Wow!

(And I see a spelling/punctuation checker in your future!)