ABSOLUTELY YES! Otherwise all the debris from the build will get into your vents and ducts. Have your contractor cover them asap and you'll probably have to get them cleaned out if they are already full of debris.

You'll have lots of dust in your house once you move in and turn your heat or air on!

How sloppy!

As soon as the HVAC guy cuts the floor vents I nail on scraps of ply to every opening. Not only do they keep debris out of the duct work, they're a safety measure to prevent trips and falls.

Ugh. Wonder why ours are not covered. I'll
Do it myself today. Should I vacuum them out first or wait til later?

Are you still working on trim? I would guess they need to condition the house at this stage of the build. Our trim carpenters cracked the vents just a touch.

Yes, trim is still going in.

They might need the conditioned air--for trim and your hardwoods, etc. They might not want them covered. But, you could vacuum them out, and then put temporary registers on/in that can "screen" a lot of the crap (esp the heavy stuff) to keep it from falling in...

Our vents are in the ceilings. But we immediately put filters on every return air within each room even though our system is filtered at the unit and not at the actual return airs. We had to tape them into place and sort of shove them in the holes because the grills aren't in an it isn't made to prefilter.

We keep them changed regularly too.

I'd like to think that our GC would have done it anyway, but who knows. It's one of many things that means a lot to us since it's ultimately our house.

Same thing with putting down Ram Board on every finished floor. We had it ready to go the afternoon of each installation.

Be proactive!