Air Conditioning - Temp Diffrence in Rooms?

Hi I recently moved into a new construction home. I have two bedrooms on the north end of my home. Identical size rooms with the return and thermostat in the hallway in between the rooms. One room maintains temp with the rest of the house. The other is always hotter in summer and colder in winter I talked to Heat air company they say 3 degree is acceptable. Well I can get it to 3 degree difference by adjusting all the vents in the house. I think this is unacceptable becuase one room is comfortable the other always hot or cold and they are just down the hall from each other. The two rooms have ducts coming off the end of the main run duct. One goes strait to the room. This is the comfortable one the other has two ducts in its run one for entry way and one for bathroom. I have closed entry way completly and bathroom most of the way. On end of house closest to Blower unit. All vents are closed 1/2-3/4 only vent in house opened fully is in uncomfortable room. I have increased pressure in that room greatly but its still uncomfortable. So what are my options? Bigger duct work? Second vent in room? Lastly is 3 degrees supposed to be acceptable room to room standard? There are days it goes to 4-5 degrees on extremely hot or cold days.

No, 3 degrees is not good. here are simple things you can check. The air temperature that come out of the two rooms A/C registers, are they same or different ? how strong the air flow is at the register , are they same or different. The only other thing you need to check is the insulation of the room, are they same ? unless you have the equipment, it is not easy to do, but you can use a small infra thermo gun (if you have one, cost around $40), you may be able to find some leaks on the wall or windows,etc. at least you can check if there are hot spots in the room and how many, how bad of them. Of course not as good as the professional equipment, but better than nothing. good luck to you.

I have a temp gun and temps coming out in both registers are withing a degree or two. Both cold now and hot durring winter. Originally there was hardly any pressure in this room but I have adjusted all the registers to help. Only issue is that its also really boosted pressure in the other bedroom also. I have that register closed about halfway but if I close it anymore the noise from it is to disturbing to sleep in that room for my daughter.

Sounds like you have air pressure problem for this room. You need figure out a way to increase the air flow into this room. I had the similar problem in one of my old houses. I ended up move the duct from the side of the main duct to the end location because the end opening is stright, not on the side, so it has much stronger air pressure. and because this duct turned several times in the attic, those turns weaker the air pressure, so I had to put in a larger size duct. Anyway, you get the picture, you just have to do something to increase the air flow. By closing other registers is not recommended. not enough air intake will make your fan work too hard, the fan won't last too long, and if not enough air go through your coil, your A/C will freeze..I don't know what else to suggest, hopefully other people on this forum can give you some suggestions..