Engine heater core – There are several reasons why your car heater blowing cold air cannot heat. It is important to understand how the heating works in your car before you can start trying to diagnose why it did not work. First, there is an electric heating element in the heating system in the car, such as portable heaters used in homes.
Parts that transfer heat to the passenger compartment is called Engine heater core. A heater core can be considered a miniature radiator. The engine coolant flowing through the heater core whiles the fan (also called a blower), blowing air through the heater core fins. When it blows air through the heater core fins, it is heated, for heating the passenger compartment.
Start by checking the coolant. As we have already said that warms the coolant heater core. So if the coolant is low, there may not be a sufficient amount to transfer heat to warm the air in the passenger compartment. After a full cooler, heater hose feel that goes through the firewall. With the engine at normal operating temperatures, BOTH of the heater hoses should be hot to the touch. If only one hot, this indicates there is a blockage in the Engine heater core or no air is trapped inside the heater core.