You have a contractor problem! Here is my suggestion. First, change your approach. Stop playing HVAC contractor. I understand feeling the need to based on how your contractor is responding, but stop, now. Escalate the problem to the local Carrier distributor. They have at least one dedicated technical advisor on staff to help a contractor who is struggling, and your contractor is clearly struggling. (Sidenote: You distributor will be either independant or factory owned.) Monday morning call the distributor. Calmly tell them you bought a brand new Carrier system x weeks ago from x contractor. It has never worked correctly. They have been out x times since the installation and they don't seem to know what to do. A good distibutor will jump right on it. First, he will talk with the contractor to review what has been done so far. He may suggest a course of action for the contractor to take or decide he needs to see the installation first hand. Push to have him see the installation. Also, confirm this is the distributor's dedicated technical guru you are dealing with and not the distributor's sales person who sometimes is dispatched to go out and smooth things over, ultimately hoping to explain away the problem. Be nice, but firm. Good luck. If you get any push back, and hopefully you won't, point them to the link below.

I would want a system that was an AHRI match. If not, wouldn't have it or install it. Now there are matches using a smaller coil to a larger condenser. Generally better dehumidification but not as good efficiency. Like most things, not a black and white situation. Depends. I want that AHRI match though. IMO

Your situation really doesn't surprise me, if I have seen it once I have seen it a thousand times. While the bedroom / bonus room have low air as you stated the combination of this problem plus no return or thermostat control in those areas just due to where the equipment is placed or the longer run of those ducts can create comfort issues in the heat of summer. When there is light exposed to what the real problem is gives a better ability to offer things that will rectify the issue. In dealing with hot spots a zone system is a higher cost option to rectify the issue for the simple reason a zone system has the ability to better control a system. The caveat if you will is the 'design'... the other thing is architectural limitations of the structure. While some situations in which a zone system is used can reduce equipment costs, that is not it's only function. If rooms are a considerable difference from the equipment that serves it, a zoned system may be the best method to rectify that issue. The other method would be to relocate the equipment to a more central location within the structure so that the ducting to each area is more equal. In a zone system the equipment will cool / heat each zone independently so while location of the equipment is still some what important, not as much as a non-zoned system. A new return added to a hot spot will help, but it may not rectify the issue 100% for the simple reason the thermostat location now can not sense temperature in that area. If you move the thermostat then the problem is merely shifted to a new area outside the reach of the thermostat. This is how a zone system excels. Provided the design is done correctly. While it's true that 2 speed, 5 speed and full on inverter systems excel in a humid climate, that is not the only purpose of those machines. Because of the high utility cost in the location of where this structure is... it is in the interest of this home owner to choose the most efficient equipment they can. If it were me I would go with Inverter system 20 SEER or higher. (5 speed or full inverter variable) If you can't afford both at once or you want to make sure a company is worth their salt, consider awarding a company with the system that has the problem area first. Tell them if they rectify the issue with the trouble spots you will reward them with replacing the other system as well. If you hire them and it goes terribly wrong, hire in another contractor to fix the problems and then you have something to use leverage to get another contractor to take over the maintenance and service of both systems... the contractor who fixes the problem system gets the right to replace the other system. Additionally given the information of those hot spot problems, trying to drop this to total of 5 tons of cooling would be a disaster. For others that happen to read this thread with similar problems I service the Katy, Texas area.

To argue whether or not someone has a license to do HVAC work or not. To consider what makes a pro a pro versus someone with just a license. And how many licks does it take to get to the center of a tootsie roll sucker? You only have a few metrics from which to judge someone who does this kind of work. You have to hope they are telling you the truth. I am very vocal about my skills and how long I have been doing this. You can go to Texas license board and view my license number to show the number is mine. I have a youtube channel that has been in existence since very early when I started the business, another way to check. Will you be able to do these sorts of things for every contractor? NO. I take things to the 'whole nother level' as the old MAD TV skit portrayed. (Keegan Michael Key) The characters on the side of my van, in my advertising were all created by yours truly. So outside of experience what is there: PASSION. If a contractor is passionate about what he does --- what does that mean. That is the easiest way I can tell you the difference. (The difference you can't compare via what something costs or doesn't cost.) If you're only in business to make money, passion is a waste of time. That's the point. I'm here posting to a board on a post in which this is not my customer and probably never will be. Passion. (So you understand the situation.) One of my characters is showing #1. This means more than what you think. Originality. I don't follow the mold. You either like this or you don't. I am a take or leave it kind of guy. I don't sell gimmicks, I sell service first and foremost, and I charge for it. Knowledge. ---------- Stipulations: If you hire me to change a part of your system, that part comes with a warranty. Part and labor if you want to pay for the extended labor I can sell you that as well - your choice. (conditions may apply) The part or part(s) of your HVAC system that are replaced are covered by the warranty. Warranty does not include maintenance related repairs. Warranty does not include the older parts of your system. If you want a system wide warranty, buy a complete HVAC system. Which will cost you more money, that is the trade off. Again your choice, you choose. --------- Because I know what I am doing, you do not get to decide what is fair or not fair in the event of another failure. So if the guy the OP hired failed to do this or that and *if* he admits that he made a mistake that's up to him to correct it. If I make a mistake I correct it and 99% of the time I correct it at the jobsite before I leave. So most of the time my customers never even know a mistake was made. This single advantage to the unskilled vs. skilled set me apart. How skilled is someone from a larger company? How will you know? *you won't* Example: you install the condenser and go check the refrigerant charge and the pressures do not look right. (If the pressures do not look right, it's not going to 'work') --- you have to *know* how to fix these kinds of problems. If you don't know, the result of this discussion on a forum board is likely the result. A HVAC installer is not likely to know, so you understand the complexities of this job and the difference from a installer, a tech and a licensed contractor. The installer is bottom rung. I do all three positions - and I charge for it. What do you want? A headache or something that works? Your choice. Anyone can do HVAC repair, even a home owner. This doesn't mean it will be done right. So saying you're a pro and actually being one --- what conclusions can you draw from this post? #Ray is one in a million? two million? If I am not please direct me to a post on this board that has half the posts I do that shows them as being a pro and actually doing this type of work *professionally*. Outside of all that I am not going to go down the path of thinking this guy you hired did something wrong, maybe he did, maybe he didn't ----- maybe the situation was fraught with failure from the get go because it sounds like the system is oversized for the structure. This again is the part in which knowing what will work and what won't. I don't sell jobs in which I think there is going to be some kind of debilitating problem. Whether that helps or not? I'll leave it to the consensus of the board to determine.