1. Low Coolant Level: Check the coolant level in the overflow reservoir. If the level is low, add a 50/50 mixture of antifreeze and water to the reservoir. Be sure to check for leaks in the cooling system if the coolant level is consistently low.
2. Faulty Thermostat: The thermostat is a valve that controls the flow of coolant to the heater core. If the thermostat is stuck closed, no coolant will flow to the heater core, preventing it from producing heat.
3. Clogged Heater Core: The heater core is a small radiator located behind the dashboard. Over time, it can become clogged with debris, restricting the flow of coolant and preventing heat from being produced.
4. Faulty Blend Door Actuator: The blend door actuator is a vacuum-operated device that controls the flow of air to the heater core. If the blend door actuator is not working properly, it can block the flow of warm air to the passenger compartment.
5. Leaking Heater Hoses: The heater hoses carry coolant from the engine to the heater core. If a heater hose is leaking, the heater core will not get enough coolant to produce heat.
