2003 Honda Accord sedan - passenger seat does not recline

Is it a power seat?? If so it could be the switch itself but possibly a limit switch. Try pressing the switch really hard or hitting it with your palm, if it moves at all even for a moment then it is infact your seat switch. Is it under warranty? IF so take it to the dealer.

on the frame on the drivers side

There should be retainer nuts on the inside. You would have to remove the inner door panel to access.

the motor has ceased get a new motor

I wouldn't ruin anything by trying things yourself

I would have a dealer check it out

The dealer I used in the past, has a seat specialist come
in on Wed only, around 5:30 after the service bays close
& one service writer hangs out until that person fixes a
couple vehicles seat issues

Means that the recirculation feature is ACTIVE. What this does is take the cabin cooled air, and re-cool it again, using very little fresh air from the outside, and allowing the air conditioner to work much cooler and efficient. Not advisable if you have a full load of passengers, and absolutely recommendable if you are going through long tunnels, or behind vehicles with visible tailpipe smoke. Keep me posted.

electric or manual?

YOU CANT REPLACE THE LIGHT YOU HAVE TO REPLACE THE WHOLE SEAT AS IT IS ONE FUNCTION.

have your brakes checked. the seat belt may be covered under warranty, ck with the dealer. I worked at a Honda Dealer in the 80's and I think their seat belts were covered for the life of the car. I could be wrong

yes they will I have swapped out many even some other honda seats will fit like civic and integra!