Why does the "TEMP" light keep coming on on my '91 buick lesabre?

[section hand]

The Answer is in Your Question,When You are moving You have Air moving thru Radiator;
Your Radiator Fan is not working or is Intermitent;
Note do not Ignore this Problem,Fan or Fan Relay is Cheap Compared to a Blown Head Gasket or Warped Heads or Cracked Heads;
I would Start the car let it run and when the
car reaches operating temp 190 Degrees raise the Hood and see what Fan is doing,Safety first stay clear of Belts and Fan;

 

[suave_house1983]

It has the 3.8 l engine. the water in the radiator is always full. after a while, like when im moving, it will shut off again?

 

[kwflamingo]

Sounds like your thermostat could be faltering - have it checked out.

 

[bandit_60]

it could be the temperature sending unit is getting bad.