You will need to consult an air conditioning contractor.
You will hear air circulating in the cold air return (or return air grille) when the heater or air conditioner is running.
Cold air return vents are the ones on the wall
A cold air return is similar to a return air grille, which is needed for air to travel to the furnace to be filtered, heated OR cooled and then recirculated.
It is never a good idea to restrict or block a cold air return.
YES! If you do not have a cold air return on your furnace, you will have much higher heating bills as you will not be circulating the cold air from your home back to the furmace to be heated again.
You actually "need" only one cold air return for a forced hot air/AC system to function; however, one cold air return per level or floor improves the efficiency of the sytem.
The purpose of a cold air return in a basement is to circulate air, allowing for proper ventilation and maintaining a comfortable temperature throughout the space.
Purchase return air filter grilles with washable filters.
You do not ever want to block or restrict air flow to a return air grille.
No. Anytime you operate your ac or heater, air must circulate through the return air grille.
Yes
Nearest to the thermostat.