* Low Coolant: The most common cause. The heater core relies on coolant circulating through it to provide warmth. If the coolant level is low, there's not enough fluid to transfer heat effectively. Check your coolant level in the overflow reservoir (often a translucent plastic tank).
* Coolant Leak: A leak in the cooling system, including a leak in the heater core itself, will lead to low coolant and ineffective heating. Look for signs of coolant leaks under the car, especially around the heater core area (usually behind the dashboard, making it difficult to spot directly).
* Faulty Thermostat: The thermostat regulates coolant flow. If it's stuck closed, coolant won't circulate properly, preventing heat from reaching the heater core.
* Faulty Water Pump: The water pump circulates the coolant. A malfunctioning water pump will hinder or stop coolant flow, leading to cold air from the vents.
* Heater Core Problems: The heater core itself could be clogged, leaking internally, or simply failing. This is a more significant problem requiring potential replacement.
* Blend Door Actuator: This small motor controls the flow of air between hot and cold. If it's malfunctioning, it might be stuck on the cold setting, regardless of what you select.
* Blown Heater Hose: A hose connecting to the heater core may have cracked or come loose, preventing coolant from flowing through.
* Faulty Blower Motor Resistor: While this won't directly affect the temperature of the air, a faulty resistor can cause the fan to run at low speed or not at all, making it feel like there's no heat, even if the coolant is hot.
What to do:
1. Check the coolant level: This is the easiest and first step. Add coolant if needed (use the correct type for your car!), but only if you can identify a leak first. Toping off coolant repeatedly without addressing a leak won't solve the issue long-term.
2. Inspect for leaks: Look carefully under the car and around the engine bay for any signs of coolant leaks.
3. Consult a repair manual or mechanic: Diagnosing the exact problem often requires more advanced troubleshooting skills and tools. A repair manual specific to your 2006 Chevy Impala will provide detailed information and diagrams. A mechanic can properly diagnose and repair the issue efficiently.
Ignoring the problem can lead to more serious engine damage, so addressing it promptly is recommended.
