My best guess is: If he is in Arizona, chances are he probably doesent have heat strips. I know It's not a smart idea, but it tends to happen alot here in Vegas also. with this warm climate we live in, my heat pump does the same thing, if it is just cycling, the temperature is pretty warm. If I turn it up a few degrees and let it run for more than 15 or 20 minutes, the air gets hot. This is with my strips turned off. I have a feeling his thermostat is satisfying before the air coming out has a chance to really heat up. I have a 4 ton unit on my house 1850 sqft. sized more for heavy heat load in the summer, so in the winter when it's 40 degrees or above, this thing really kicks butt. I'm sure his is probably reacting the same way, 5 ton 2220 sqft.