Without the heating system in vehicles, we would all freeze while driving to our destinations in the winter months. Most of us take this system for granted because if it breaks, we would be miserable driving without it! Let’s take a look at how the heating system works to keep us comfortable in the cold weather.
There are a few basic components to the heating system; the heater core, blower motor/fan, heater hoses, heater control valve, and the HVAC (heating, ventilation, air conditioning) control panel inside the cabin. The cooling system components that interact with the heating system are the coolant, thermostat, radiator, and water pump.
The heating system is connected to the engine cooling system and uses heat from the engine to warm up the vehicle. The heater core acts like a small radiator that is connected to the engine cooling system. The cooling system is filled with liquid coolant that circulates between the engine and the main vehicle radiator. The thermostat valve blocks the circulation through the main radiator when the engine is cold; it opens when the engine reaches the specified temperature. Once the vehicle gets to operating temperature the thermostat opens and allows the coolant from the cooling system to circulate through the engine passages removing the heat from the engine sending it into the radiator.
Airflow in the HVAC system of a car.
The blower motor of the HVAC system creates the airflow. The air flows through the A/C evaporator and then through the heater core (see diagram above). A fan is positioned in front of the heater core to blow cold outside air over the fins. Various ducts and doors inside the HVAC system distribute the warm air to the vents and into the cabin of the vehicle. The temperature blend door is the door that controls the mix of warm and cold air.
If the Air is Not Hot Enough it May be Because of One of These Common Problems:
- If the air blowing from the vents is not hot enough, the first thing to check is the coolant level in the overflow bottle. If it’s low, the coolant must be topped up and the cooling system must be checked for leaks. You will know there is a leak in your vehicle’s heater core if you can smell the sweet aroma of coolant when your heater is on. Leaks can cause a cabin full of white steam that can fog your windows.
- If the heater core becomes clogged with rust or sludge, you will no longer have heat as well. From time to time the A/C system needs to be recharged to bring it back up to maximum efficiency.
- A thermostat that is stuck open can also cause long warm-up times, however, in most cars, the Check Engine light comes on if the thermostat is stuck open. A symptom of a stuck-open thermostat is when the engine temperature drops below normal when driving on a highway.
- In some cars, if the temperature blend door inside the HVAC system is not functioning correctly, it can also cause a lack of heat from the vents. Often, parts of the cable mechanism in the HVAC system wear out, causing the blend door not to close off the cold air completely. You can tell this is the issue because it may feel like the hot/cold knob is jamming and not moving all the way to “Hot”.
- If there is a lack of airflow from the vents even at full blower motor speed, the cabin filter must be checked. A dirty cabin filter can restrict the airflow in the HVAC system. Normally, once the engine is fully warmed up, the air from the vents should be very warm at any speed or when the car is stopped at a red light.
The heating system in your vehicle is designed to keep you warm while the temperatures outside are cold. Properly maintaining the cooling system is key for the heating system of your vehicle to work efficiently. Having the coolant in your engine flushed regularly and refilled with the clean coolant/water mix is very important along with getting any leaks repaired. If your heating system is not working properly it is important to come down to Luke’s Auto Service in Verona, NJ to have it checked out as soon as possible because, depending on the issue, this may result in engine damage.
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