The builder of the apartment complex likely just undersized the unit, they'll do this with the normal kind of heat pumps-- air conditioners-- too, and hope its not so undersized that it becomes an actual problem.
I rented someone's condo circa 2004 that did this with the air conditioning. Hot summer day? Just warm air coming out of the AC. (It was the kind where the cooling is done centrally and you just have an air handler in your unit.)
Now that I think about it, that happened in both apartments I lived in in Chicago. I remember going for a bike ride one summer afternoon with a friend. Got home, AC didn't do anything, so I went to the grocery store and bought a bag of ice, poured it in my bathtub, and rolled around in it until I was numb. I was cold the rest of the day. Very effective but do the math correctly when you install building-wide air conditioning systems.
