2005 Chevrolet Express Van Owner's Manual - Page 256

If you get the overheat warning with no sign of steam, try this for a minute or so: 1. In heavy traffic, let the engine idle in NEUTRAL (N) while stopped. If it is safe to do so, pull off the road, shift to PARK (P) or NEUTRAL (N) and let the engine idle. 2. Turn on your heater to full hot at the highest fan speed and open the windows as necessary. If you no longer have the overheat warning, you can drive. Just to be safe, drive slower for about 10 minutes. If the warning does not come back on, you can drive normally. If the warning continues, and you have not stopped, pull over, stop, and park your vehicle right away. If there is still no sign of steam, push down the accelerator until the engine speed is about twice as fast as normal idle speed for at least three minutes while you are parked. If you still have the warning, turn off 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. Cooling System When you decide it is safe to lift the hood, here is what you will see: A. Radiator Pressure Cap B. Coolant Recovery Tank C. Engine Cooling Fan(s) If the coolant inside the coolant recovery tank is boiling, do not do anything else until it cools down. 5-26