2010 Hummer H3 Owner's Manual - Page 288

10-22 Vehicle Care At any time during this procedure if coolant begins to flow out of the filler neck, reinstall the pressure cap. Notice: If the pressure cap is not tightly installed, coolant loss and possible engine damage may occur. Be sure the cap is properly and tightly secured. Then check to see if the engine cooling fans are running. If the engine is overheating, both fans should be running. If they are not, do not continue to run the engine and have the vehicle serviced. The air conditioning might stop working if the engine is too hot. This is normal and helps cool the engine. Notice: Engine damage from running the engine without coolant is not covered by the warranty. Notice: If the engine catches fire because of being driven with no coolant, your vehicle can be badly damaged. The costly repairs would not be covered by the vehicle warranty. Engine Overheating 6. Start the engine and let it run until you can feel the upper radiator hose getting hot. Watch out for the engine cooling fan. 7. By this time, the coolant level inside the radiator filler neck might be lower. If the level is lower, add more of the proper DEX‐COOL coolant mixture through the filler neck until the level reaches the base of the filler neck. 8. Then replace the pressure cap. The vehicle has an indicator to warn of engine overheating. A coolant temperature gauge is displayed on the instrument panel. See Engine Coolant Temperature Gauge on page 5‑9. You may decide not to lift the hood when this warning appears, but instead get service help right away. See Roadside Service on page 13‑5. If you do decide to lift the hood, make sure the vehicle is parked on a level surface.