I have a brand new Infinity system with two 25HNA6 3-ton units. Last two days have been brutal here in Philly. Temps around 95-98F. First floor system is cooling well and keeps the temp at 77F, which is my setting. The 2nd floor system is not keeping up. The setting is 77F, but the t-stat is reading 80F indoor. The air out of the vents is coming out very cold. It's running in high stage cooling, but can't seem to catch up until the nighttime, when the outside cools off a bit.
What can be done? Is that a sign of improper sizing? How should the system behave in such hot weather anyway?