After waiting 30+ minutes on a late crew member from another flight in Albuquerque we had to wait over an hour to take off because Denver had too many planes on the ground.

Once in Denver the Southwest Pilot was trying to convince people that they were having difficulty getting fuel into the planes... as though it were freezing. It was single digit temperatures and well above what jet fuel freezes at.

Had to wait 3hrs in line for a gate to park the plane at and then another 45min or so for maintenance crew to fix jetway that wouldn't extend out to the plane.

Finally took 2 trains to get to St Louis because Southwest dropped the ball, kicked it off a cliff, and watched this Christmas go sailing off into the distance.

yup

Really depends on the unit.

Multi-zone units typically have variable speed motors.

Single zone units usually have single speed motors. Some have blowers mounted directly on the motor shaft. Some are belt driven. With a belt drive you have a little flexibility to swap pulleys to adjust he cfm.

You also need to make sure the rest of the ductwork can handle the increase in pressure from closing off one of the ducts.

I've seen more than a few main ducts burst open because people thought they could just cover a register or two in rooms they weren't using and didn't take into account that the blower was still trying to move the same volume of air through less openings.

I need this. Ghost pepper sauce just not cutting it anymore.

They are down for anything.