It is never a good idea to restrict or block a cold air return.
The air from the register/vent blowing into a bedroom must find its way back to the central cold air return somehow. This is usually accomplished by having a large enough crack/cut under the door above the carpet or flooring for the air to move through. If you do not allow the bedroom air to flow back to the central cold air return, the bedroom will become uncomfortable - usually to hot or to cold. Another solution is to install a grille in the bedroom door to allow the air to flow through.
The best thing to use to block a cold air return is a piece of a cardboard box cut to fit the size of the return. Other options include towels or blankets.
You do not ever want to block or restrict air flow to a return air grille.
Supply and return grille locations are figured by the HVAC engineer or the contractor.
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.
Do not place a return air supply in your bathroom; and, unless your heating your closet you do not need one in there as well.
the temp. is to low and they have not yet got used to life
When you first get out of bed in the winter, your body temperature drops due to the cold environment. However, once you return to the same room after being outside for a while, your body adapts to the room's temperature and warms up. This may make the room feel warmer to you since your body has adjusted to the change in temperature.
10 horsepower.
Cold Case Files - 1999 The Bedroom Basher was released on: USA: 22 February 2005
A 12 volt battery with about 600 cold cranking amps works well. A little bigger if you live in a cold climate.
Cold air return vents are the ones on the wall