Buick 1993 Century Owner's Manual page 198

If No
Steam
Is Coming From Your-Engine:
If you get the overheat warning but
see
or hear no steam,
the problem may not be too serious. Sometimes the
engine can get a little too hot when you:
Climb a long
hill
on a hot day.
Stop after high speed driving.
Idle for long periods in traffic.
Tow a trailer.
If you get the overheat warning with no sign of steam, try
this for a minute or so:
1. Turn off your air conditioner.
2. Turn on your heater to full hot at the highest fan speed
and open the window as necessary.
3. Try to keep your engine under load (in a drive gear
where the engine runs slower).
If you no longer have the overheat warning, you can
drive. Just to be safe, drive slower for about ten minutes
If the warning doesn't come back on, you can drive
normally.
If the warning continues, pull over, stop, and park your
vehicle right away.
If there's still no sign of steam, you can idle the engine
for two or three minutes while you're parked, to
see
if
the warning stops. But then, if you still have the warning
TURN OFF THE ENGRVE AND GET EVERYONE
OUT OF THE VEHICLE until it cools down.
You may decide not to lift the hood but to get service
help right away.