1. Coolant System Issues:
* Low Coolant: The most obvious. Check your coolant level in the radiator and overflow tank. If low, add the correct 50/50 mix of coolant and distilled water (never just water). A leak somewhere in the system is the likely cause of low coolant. Look for visible leaks around hoses, the radiator, water pump, and thermostat housing.
* Faulty Water Pump: The water pump circulates coolant. A failing pump won't circulate coolant effectively, leading to overheating. Listen for unusual noises (whining, grinding) from the pump area.
* Clogged Radiator: A radiator choked with debris restricts coolant flow. This can be visually inspected (carefully!), or a pressure test might be needed to confirm.
* Faulty Thermostat: A stuck closed thermostat prevents coolant from circulating until it reaches its opening temperature. This can cause overheating. A stuck open thermostat could also contribute, but is less likely to cause overheating.
* Air in the Cooling System: Air pockets prevent proper coolant flow. Bleeding the cooling system (removing air bubbles) is often necessary after coolant changes or repairs.
* Radiator Cap: A faulty radiator cap can't maintain proper system pressure, leading to boiling and overheating.
2. Problems with the Heating System:
* Faulty Heater Core: Although the car is blowing *cold* air, a clogged or leaking heater core can prevent hot coolant from reaching the heater core, resulting in cold air. A leak could also lead to low coolant levels.
* Heater Control Valve: This valve controls the flow of coolant to the heater core. A stuck closed valve would prevent hot coolant from reaching the heater core.
* Blends Door Actuator: This component controls the mixing of hot and cold air. A malfunctioning actuator might be stuck in the cold air position.
3. Other Potential Issues (less likely):
* Head Gasket Failure: A blown head gasket can allow coolant to leak into the engine's cylinders or oil, but usually this presents with other symptoms like white smoke from the exhaust, milky oil, or loss of compression. It is a significant problem.
* Temperature Sensor: A faulty temperature sensor might give incorrect readings to the engine's computer, leading to improper cooling system operation.
What to Do:
1. Safety First: Never open the radiator cap while the engine is hot. Let it cool completely before checking anything.
2. Check Coolant Level: This is the first and easiest step.
3. Visual Inspection: Look for visible leaks.
4. Listen for Unusual Noises: Pay attention to any noises coming from the engine compartment, especially around the water pump.
5. Consider a Pressure Test: A mechanic can use a pressure tester to check for leaks in the cooling system that might not be visible.
If you are not comfortable working on your car yourself, take it to a qualified mechanic for proper diagnosis and repair. Ignoring overheating can lead to serious engine damage. The cold air is a symptom; the underlying problem needs to be addressed to prevent more serious consequences.
