Well there probably ISN'T a temp warning light and by the time you see
steam, the engine has blown a head gasket or worse. What does the temp
GAUGE read?

If the temp gauge is not in the middle of the gauge you have a
problem.  If the gauge goes into the red then there is a high chance
that the head gasket will be have been damaged.

You topped up the coolant?  Did you do check the radiator header tank
at the rad pressure cap in addition to the expansion tank?  If there
is air in the radiator header tank the expansion system doesn't work
and the coolant level in the engine can drop without using coolant
from the expansion tank.  When the engine coolant level drops the
temperature gauge lies as it shows the temperature of the air and
steam in the system and not the coolant.

PS don't depend on warning lights most work like the oil pressure
light.  When that one lights up it means you have a wrecked engine.

Make sure the electric fans come on when they are supposed to. After driving
a couple of minutes, the fan should turn on and cycle off periodically. If
you turn the AC on, both fans should be on all the time.

Remco

That's funny , most Nissan's don't have a "temp" light, they have a gauge.

It may also help to know what type of vehicle we are dealing with