* Low Coolant Level: This is the simplest and easiest check. Open the radiator cap (when cool!) and check the coolant level. If it's low, you need to add coolant (the correct 50/50 mix of coolant and distilled water). Low coolant prevents sufficient heat transfer. A leak somewhere in the system is the likely cause of low coolant.
* Thermostat Stuck Open: The thermostat controls the flow of coolant through the heater core. If it's stuck open, coolant continuously bypasses the heater core, preventing it from warming up. This is a common problem.
* Heater Core Problems: The heater core is a small radiator inside the car that warms the air. It could be:
* Clogged: Restricting coolant flow and heat transfer.
* Leaking: This would result in coolant leaking into the cabin (you'd see a sweet-smelling liquid and possibly a damp carpet).
* Blocked: Perhaps by debris or corrosion.
* Water Pump Issues: A failing water pump might not circulate coolant effectively, impacting the heating system. A weak pump will still circulate some coolant, so this isn't the most likely cause for *only* cold air, but it's a possibility.
* Blend Door Actuator/Cable: This controls the amount of hot and cold air mixed. If the blend door is stuck in the cold air position, you'll only get cold air regardless of the settings. This is a more common problem in later models, but still possible.
* Temperature Control Valve: Some systems have a temperature control valve that regulates coolant flow to the heater core. This could be stuck closed.
Troubleshooting Steps:
1. Check the coolant level. This is the first and easiest step.
2. Check for coolant leaks. Look under the car for any signs of leakage.
3. Feel the heater hoses. When the engine is warm, feel the two hoses going to the heater core. One should be hot (from the engine), and the other should be warm (going back to the engine). If both are cold, the problem is likely the thermostat, heater core, or water pump. If only one is hot, the heater core is likely clogged or leaking.
4. Check the thermostat. This usually involves removing it and checking if it opens when immersed in hot water. (There are numerous online videos demonstrating this).
5. Inspect the blend door actuator. If you're comfortable with some car repair, you can access this to check if it's working correctly and the cables are not broken.
Important Note: Working on your car's cooling system involves hot coolant, so be very careful and let the system cool completely before working on it. If you're not comfortable performing these checks or repairs yourself, take your car to a qualified mechanic. Ignoring a heating/cooling system problem can lead to engine damage.
