Condominium and high-rise systems
Multi-family equipment is a different animal from residential split systems. Vertical stack fan coil units, water-source heat pumps tied to a building loop, and through-wall PTAC units all fail differently and all sit inside somebody else's rules. A water-source heat pump that will not run may be a unit fault or may be the building loop; a stack fan coil may need the riser isolated, which is a building decision rather than a homeowner one. Knowing which conversation to start saves the most time on these calls.