Chevrolet 1994 Astro Passenger Owner's Manual page 197

When
you
decide it's safe to lift the hood, here's what you'll see:
A. Coolant recovery tank
B. Radiator pressure cap
C. Engine fan
If the coolant inside the coolant recovery tank is boiling, don't do anything
else until it cools down.
The coolant level should be at or above FULL. If it isn't, you may have a
leak in the radiator hoses, heater hoses, radiator, water pump or somewhere
else in the cooling system.
NOTICE:
Engine damage from running your engine without coolant isn't
covered by your warranty.
If there seems to be no leak, start the engine again. See if the fan speed
increases when idle speed is doubled by pushing the accelerator pedal down.
If it doesn't, your vehicle needs service. Turn off the engine.
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