Next time you have it serviced ask the tech to compare your measuring device to theirs. If you manually trigger your a/c to dehumidify remember the longer it runs the better it will dehumidify.

Had somewhat similar issues
 

I think your first step should be to have Munn's (or whoever did the initial HVAC install) come check the Thermostat. We bought a new Iris last winter while we were here and then went back home for the summer. I too have the Ecobee thermostat and was getting all sorts of really high humidity readings (>75) in the summer, and had a hard time controlling it even with the AC running. When we got here full time in October I had Munn's come out again and they changed out the thermostat. Since that the readings have been more reasonable. I'd certainly have the thermostat checked before investing in a dehumidifier.

Humidity in Home Too High
 

Surprised no one has mention this. I did this with the heat and ac set to off on the thermostat. Then go to System. Than go to fan setting. this way you can set the unit to run the fan once every hour for a certain length of time. I have mine set for 5mins. this will work whether the unit is on or off. That way you at least have the air in the house circulating which should help with the humidity. You can also note what time of day the fan will run. Good Luck and Happy Holidays, Mike

I’m sorry, I can’t resist. What the definition of “Relitive” humidity?🤣

Arizona
 

Last time I was in “The Valley of the Sun” it was 113 degrees and it was May 30. You could be trading one small problem for a bigger one. Op, would be better off to buy a dehumidifier for their house IMHO.

Did you read the link in the post your quoted? First of all, there is no such thing as "Relitive humidity". It is R E L A T I V E humidity. :D :D I first learned about it in 6th grade science class. That being said GOOGLE is your friend. Here are a few explanations to get you started which you could have easily looked up on Google if you REALLY wanted to know:

• Relative Humidity - Tree House Weather Kids - University of Illinois Extension
• Difference Between Humidity and Relative Humidity | Difference Between
• Relative humidity - Simple English Wikipedia, the free encyclopedia
• Relative Humidity - an overview | ScienceDirect Topics
• What is Relative Humidity?

In case you are too lazy to click on the links here is one explanation copied from the FIRST link explained for children and so even children can understand:

Relative Humidity (credit to: Relative Humidity - Tree House Weather Kids - University of Illinois Extension
We describe how much water vapor is in the air by using the term relative humidity. Relative humidity tells us how much water vapor is in the air, compared to how much it could hold at that temperature. It is shown as a percent. For example, a relative humidity of 50 percent means the air is holding one half of the water vapor it can hold. Again, this is all dependent on the temperature.

What is an "Ecobee 5" ? I'm curious as I have the 3 w/voice control which they now call "Smart Thermostat with Voice Control." There is no "5" (or 4) on their website. I always like to upgrade. :)

By the way, if you have the Voice Control model check out the small remote smart sensors you put in various rooms. Really work great to keep temps balanced when running A/C.

I have the same problem as you do - but different equipment. Agree keep your fan on auto to minimize its running. Did not know the windows opened so we keep them closed all year. In the last week or so our humidity has been going over 60% as it has done in prior years in the winter months. Do not want to run the A/C to lower the humidity so we purchased portable dehumidifiers. One I let drain in the laundry room and the other in the guest rooms' tub. I think if you do not keep the humidity at 60 or below you could get a mold problem. Depending on the design of your home one dehumidifier may do the trick. I would try to avoid having to empty the dehumidifiers manually.

Portable dehumidifier
 

As we are often not there for some months on end, humidity control is a big issue.

We have a portable floor dehumidifier in our central living room with a built in evacuation pump that works perfectly.

In addition, I have the fan setting on the Ecobee set for the fan to run each hour, for 5 or 10 minutes each hour, circulating the air through out the house. The A/C system has no reason to run otherwise and I maintain a 50% humidity level in the house easily without needing to running any heat or A/C. I have my heat and A/C setting very wide JIC we get extreme temperatures, but I barely recall that ever happening.

Prior to this set up, I was using the A/C system to control humidity while away. I had to keep the home much cooler than I desired. This is so much less taxing on the system.

BTW: I do this at two properties and both environments are perfect.

Garage. I also have a split system in my garage. There my humidity is the same challenge I had in the house. Presently I am cooling my garage instead of the house and still, humidity trends higher than I like. On my return, I intend to get another dehumidifier with pump...(Costco) and will expect an energy cost savings, less system wear, and most importantly, great humidity results.

2-stage heat pump
 

I also have the Carrier 2-stage system. The best solution to controlling humidity is a 2-stage heat pump. When the weather is not too hot, the system will run the AC compressor at a slow speed. Since the slow speed can't cool as quickly, it runs longer. This is more energy efficient but has the added benefit of removing more humidity during the longer run times.

2-stage systems are more expensive, but something you might consider when your current system dies.

I couldn't agree more!

I just replaced two aging systems with new Carrier Infinity Systems with variable speeds like you were describing. Multi stage and speed systems are unfortunately extremity expensive and I don't think most would go for such a solution, particularly if their existing system was otherwise still good.

With a degree of frugality in mind for others, the stand alone portable dehumidifiers, turned out to be a really good solution with a bonus of only costing for each home around $200. I keep them on a smart switch but I never have to cycle that as they dehumidify down to the specified humidity level I select, and go on and off automatically.

Individual stand-alone dehumidifiers are the best for reducing humidity in your home year round as needed. And the great thing is that you don't need to run your air conditioner to accomplish that. They do put out a small amount of heat, but it's a very small amount. They work extremely well and last for years.

To monitor your indoor and outdoor temperature and humidity, I recommend one of these Acurite Temperature/Humidity meters. They work great and are very accurate. Amazon.com