Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSOLDSMOBILE2004BRAVADA AWDREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 25 (HVAC SYSTEMS - AUTOMATIC)PERFORMANCE TESTSHEATING SYSTEM PERFORMANCE
2004 Oldsmobile Bravada AWD
Heating System Performance
2004 Oldsmobile Bravada AWDSECTION Heating System Performance
WARNING: This page is about a different car, the 2002 Oldsmobile Aurora. However, it is still accessible from the selected car via links, so may be relevant.
- Inspect cooling system for low coolant level, loose or worn drive belt, leaking, kinked or damaged heater or radiator hoses or damaged radiator cap. Repair any problems found. If no problems were found, start engine and allow engine to idle in Park. If engine reaches normal operating temperature, go to next step. If engine does not reach normal operating temperature, see appropriate ENGINE MECHANICAL article in ENGINES.
- Move vehicle outdoors. Close all doors, windows and hood. Run engine until it reaches normal operating temperature. Place thermometer into center instrument panel outlet. Select vent position of mode control button. Select maximum blower speed. Place temperature control knob to maximum hot position. Measure and record temperature of air delivered. If air temperature is near 120°F (49°C) at 0°F (18°C), 135°F (57°C) at 32°F (0°C) or 140°F (60°C) at 50°F (10°C), inspect cowl, air inlet valve and HVAC module case for cold air leaks. If air temperature is not near specified values, go to next step.
- Start engine and allow to idle. Depress mode control button until lower position is displayed. Select lowest blower speed position. Turn temperature control knob to maximum hot position. Feel for a minimum temperature of 85°F (24°C) at heater inlet and outlet hoses. If heater inlet hose is warm and outlet hose is cold, check thermostat for proper condition and installation. Correct any problems found. If thermostat was okay, go to next step.
- Remove heater hoses and back flush heater core. Reconnect heater hoses. Drain and refill engine coolant. Start engine and allow to idle. Depress mode control button until lower position is displayed. Select lowest blower speed position. Turn temperature control knob to maximum hot position. Feel for a minimum temperature of 85°F (24°C) at heater inlet and outlet hoses. If both heater inlet and outlet hoses feel warm, operate system to very repair. If both heater core inlet and outlet hoses do not feel warm, replace heater core. See HEATER CORE under REMOVAL & INSTALLATION.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.