A/C works great in all but one room
My home is about 4 years old, a/c works great in most of the house. However, we recently upgraded one of the extra rooms to a nursery from being just a guest room. No problems during the winter months and early spring, but now that it's summer... different story. That single room is blowing about 10 degrees warmer than the other vents throughout the house. A/C guy came out and verified it. He checked the charge on the system, which is good. He then checked the coils and it turns out the top 1/3 of the 5-ton Goodman coils is warm, not cold. He then confirmed that the furnace and outside unit are both 4-ton. All the ducts are good to go, no leaks, connected correctly. My problem is that this one room blows room air tempurature air while the rest of the house blows nice and cold. Any other suggestions on a fix? If the installer screwed up, do they normally correct issues like this?