Chevrolet 1995 Astro Cargo Owner's Manual page 186

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.
See "Driving on Grades" in the Index.
If you get the overheat warning with no sign of steam, try this for
a
minute
or so:
1. If you have an air conditioner, turn it off.
2. Turn on your heater to full hot at the highest fan speed and open the
3. If you're in a traffic jam, shift
to NEUTRAL (N); otherwise, shift to the
highest gear while driving
-
AUTOMATIC OVERDRIVE
(a)
or
DRIVE
(D).
window as necessary.
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, push the accelerator until the engine speed is
about twice as fast as normal idle speed. Bring the engine speed back to
normal idle speed after two or three minutes. Now see if the warning stops.
But then, if you still have the warning, turn @'the engine 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.