The Heating System

The temperature in Athens GA and North Georgia dips below freezing, and the wind chill drops the temperature to the negatives. Toes and fingers numb. Teeth chatter. We escape the cold by running from the building to the car. In Georgia, the weather seems to have a mind of its own and can change from sunny and 75° to sleeting below freezing in the blink of an eye. Georgia’s crazy weather can make us thankful for the air conditioning one day and thankful for the heat the next. Keeping a constant check on the air conditioning and the heating system ensures that you will not be caught sweating or shivering whenever the fickle Georgia weather decides to change its mind.

How Does the Heating System Work?

When the driver flips the dial to heat in the cabin, a complex heating process occurs under the hood of the vehicle. The heating system of a vehicle utilizes heat from the engine to heat the cabin of the vehicle, which is why the heat does not work without turning the ignition. The heating process begins when the engine runs long enough to get warm. The heating system and the engine’s cooling system work along the same circuit, and the heat system uses heat-absorbing coolant in its own process. At the correct temperature, heated coolant begins traveling through heater hoses into the heater core. The plenum, also known as the heater box, holds the air conditioner evaporator and the heater core.  A system of ducts join at the plenum box, and the plenum diverts the air received through various vents.

How Does the Heat Flow Through the Heating System?

The blower fan ultimately pushes air through the ventilation system in the vehicle. The air deflection door in the heating system swings open and close through manual, vacuum, or electrical mechanisms to control the direction of the air flow so that air mixes and stops from one vent system to another.  The electric blend door actuator links directly to the control panel in the vehicle’s unit and controls where the air comes out in the vehicle, such as the defrost, the vents that blow directly on the passengers, and the floor vents. without the electric blend door actuator, the heat would not blow through the desired vents.

Check out the HVAC Tab for a more visual representation of the Heating System.


Problems with the Heating System

The Thermostat

The thermostat in the vehicle’s cooling system controls the amount of coolant released in the system to keep the engine cool.  To heat a cold engine up faster, less coolant travels through the engine’s system. To cool down an engine, more coolant enters the engine. When the thermostat goes bad, the thermal valve may remain stuck open or shut, which causes the engine to overheat or run cool. A bad thermostat means that the coolant may not heat up long enough in order to properly heat the cabin of the vehicle.

Grime Build-Up

The heater core functions similarly to the radiator and is subject to some of the same problems. Coolant is the most important fluid in the heating system. Like all other fluids in a vehicle, over time, the coolant picks up dust, dirt, and other contaminants. Rust and sludge in the system prevent coolant from travelling properly to the heater core. Having a coolant flush removes all of the contaminants, rust, and sludge from the system by replacing the old coolant with new coolant. With a grime build-up, the heat should function better after a coolant flush.

Leaks in the Cooling System

Leaks in the system also cause the heating system to malfunction. If the driver and passengers can smell the sweet aroma of coolant, then the cooling  system likely has a leak somewhere. Leaking fluid can cause the cabin to fill with thick, white steam that creates heavy condensation on the windows, which can cause damage to the windows. If the vehicle exhibits any of these symptoms or needs coolant refilled more frequently than previously, the system may have a leak. Leaks in the system can be difficult to find and should be assessed by a certified mechanic.

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