Can I compare a weak guest-space vent with a strong vent in the main house?
The comparison may involve separate systems. First identify which rooms share the affected equipment. Describe weak airflow within that group instead of assuming all vents are connected.
Group the affected rooms
List the rooms with weak air and the control you use for them. Include a room with normal flow if you know it uses the same unit. Say when the connection between rooms and systems is unknown.
Do not trace ducts through a ceiling or under a building to work out the layout. Old plans, install records or the service visit may answer that. For the call, describe the rooms where you notice the problem.
Separate air movement from air temperature
Is there very little air, air that feels cool, or a cold room despite clear flow? Lack of heat and lack of airflow do not always need the same repair.
Look for blocked grilles where you can see them safely. Note any recent filter change on the affected unit. Leave covers and duct joints alone. A clear grille does not prove that the whole air path is clear.
Limit the proposal to the confirmed system
Ask which unit and air path are involved before you approve a motor or duct repair. Work in one building may not affect a separate system. New ducts joining spaces would be a distinct project.
Give the Golden Gate Estates address, building location and access route. Ask if the price includes gaining access and patching any finished surface. Clarify who approves and pays for that work before it starts.
More about this heating problem
Should I adjust dampers to compare the two spaces?
No. Do not change unknown duct controls as a diagnostic trial. Record the affected rooms and let the system layout be established during the assessment.