If the mold looks like its growing from the bottom up, or from a spot and outwards, and if there is any soft drywall, it probably is from a leak.However, I have seen cluttered houses get surface mold on exterior walls because of bad ventilation, the clutter doesn't let air flow and some walls (especially exterior facing northeast, where it gets no sun) can be cold enough to encourage condensation.

In addition, he/she understands heat transfer, pressure gradients they relate to volume, capacity and air flow velocities, state transitions, voltage/amp/resistance as they relate to three-phase, series, paralleled systems, blah blah blah.

Covered in plastic with negative air flow pressure sucking any dust away.

(I previously had 1 furnace from my basement heating entire 4 units.After I installed my electric baseboards, the city inspector now is asking me to separate the HVAC ducts across each apartment where there is no shared air flow.

Strange analogy, but the furnace motors were overworking to keep a reduced return airflow flowing over the Evaporator Coil.

He will verify all stages are running, verify proper gas pressure, verify proper air flow and also can determine btu capacity you have vs btu capacity needed for the space.

Also, you'll need to make the space compliant with the current Florida Building Code as well as the Energy Code, which means all the things a bedroom needs to have: Insulation, windows for egress/airflow, closet with light, etc.

Some problems we have known about since the first walk-through and that would likely cost us money in the near future are:The stairway from the first floor into the basement must be rebuiltNew windows must be installed in the third floor for better airflow in the summerBaseboard electric heating will need to be installed on the third floorSome rehab/repairs need to be done on the eaves and soffitsSemi-circle steel barriers should be installed outside of the basement windows and we should eventually replace the old basement windows with glass block windows.

Learn how to use a multi meter to diagnose basic electrical issues and air flow issues.

Everything works, but the air flow doesn't get to the 2nd floor very well in the master bedroom.