Our air conditioning unit is located outside, looks like its just a fan, and has two tubes running to it. All air conditioning vents/ ducts are in the ceiling. One room in our home however does not cool anywhere near as well as the rest of the house. This room is located furthest away from the unit outside. We have closed all other vents in the home except the one in this room and one other. What kind of unit do you think this is and how does it work? Do you think a duct in the ceiling that goes to the warmer room is disconnected or something? This is a newly constructed home in Arizona built in the last 2 yrs.

our air conditioning unit is located outside, looks like its just a fan, and has two tubes running to it. all air conditioning vents/ ducts are in the ceiling. one room in our home however does not cool anywhere near as well as the rest of the house. this room is located furthest away from the unit outside. we have closed all other vents in the home except the one in this room and one other. what kind of unit do you think this is and how does it work? do you think a duct in the ceiling that goes to the warmer room is disconnected or something? this is a newly constructed home in Arizona built in the last 2 yrs.
You need to check 3 things.
1. Is the ductwork that runs to this room actually connected?
2. You usually need more "make up" air (return air to the farthest room). Have you verified that you have a large enough return air duct? It should be at least 1-1/2 to 2 times larger in diameter than the duct that actually delivers the heat and cold air to the room in question. Also check to see if these ducts are insulated.
3. Have you had a HVAC contractor check the velocity of air coming to this room? If the velocity is lower in this room than the rest, this needs to be dealt with. One method is to cut round sheet metal pieces the diameter of the inside of the duct work, and cut a smaller hole in these to "balance the system... in other words, restrict the air flow a little to all of the other rooms to allow more of the available air to reach the problem room.
You have not indicated two important facts here. a. Is it an upstairs room?
b. Does the room face the south with a lot of windows that soak up the sun, allowing this room to really heat up.
If you can resolve these issues, you should have the problem solved.
3.

Regarding the above post,

Does the room have lots of windows that face west? Generally, west facing is much hotter in the summer, and south is hotter in the winter.

I have the same problem, ceiling is vaulted and about 10' high. It's hotter in the summer and colder in the winter. Vent is at the top neer the ceiling. Room is hotter than rest of the home all the time in the summer. It doesn't matter what time of day and the same for the winter with the coldness. What should we do?

I have the same problem, ceiling is vaulted and about 10' high. It's hotter in the summer and colder in the winter. Vent is at the top neer the ceiling. Room is hotter than rest of the home all the time in the summer. It doesn't matter what time of day and the same for the winter with the coldness. What should we do?

Do you have large ceiling fans with the fan hanging about 6-8" from the ceiling? If not, installing a couple of them and running them on slow speed will help, as they will keep the air circulating.
I would suggest that you install reversible fans, so they can blow down in summer, and up in the winter.

Fans on high ceiling rooms will mix the warm air on the ceiling into the cooler air in the living space, so it is not always the best way to feel cooler.