Compartment Heat…Check.
Posted By Craig On February 4, 2007 @ 8:18 pm In Automotive | 1 Comment
Remember “My Daughter’s First Car”? Well, she had her first problem with it! With the onslaught of “Mr. Freeze,” everyone has the opportunity to perform an important test: Compartment heat…check!
How many of us actually test the heater in our cars until it is actually time to use it? How many of run the air conditioner during the winter months? Which isn’t a bad idea once in a while for a short time, it keeps things lubricated. Well, my daughter finally found out that her heater didn’t work and during the worst time…cold weather.
In our area of the world, the temperatures can get pretty low for extended periods of time. My daughter, being the teenager that she is, has places to go and people to see. A broken heater is a real problem don’t you know.
My wife suggested that the heater core was bad. Why does everyone automatically think that the heater core is bad? Like the heater core is the only component in a car’s heating system. Apparently, my wife has seen heater cores go bad; I, on the other hand, have not.
In a typical “Made in the USA” car, the heat comes from the most logical heat generator: The engine! Your engine’s cooling system has an important job: it is responsible to maintain your engine’s operating temperature to the most optimum degree possible. The engineers determine what that optimum operating temperature is. My truck operates anywhere from approximately 195° Fahrenheit (F) to approximately 215°F. The engine can operate at that temperature almost forever. Problems arise when the operating temperature increases above that point or much below that point. Obviously, the higher the temperature is above the optimum, the greater the chance of engine failures. But what happens if the temperature is lower than optimum? Ever wonder about that?
Your engine is similar to the human body in that it requires a certain temperature for proper operation, in the case of my truck, it is 195°F; in the case of our bodies, it is 98.6°F. Our bodies start to shut down if our temperature drops to a minimum of 86°F and my truck’s heater would cease to work properly if the temperature drops to 125°F or less and the outside air temperature (OAT) is below freezing. Additionally, the engine combustion process would not be as efficient at lower operating temperatures, and the spark plugs would begin to get clogged with carbon deposits. If one does not allow their engine to warm up properly after being “cold-soaked” (the temperature of the engine equals the OAT), one can damage the engine’s internal mechanisms by putting the strain of just 55 MPH before the engine has had time to warm upWell, this story is about my daughter’s car heater. The reason I went into the detail concerning engine operating temperatures is because without the proper operating temperature, your car’s heater cannot give you the heat you need to stay warm when the weather outside is frightfully cold. The figure below is a car engine with four important parts of the engine’s cooling system: the radiator, water pump and heater core and thermostat, which is located where the star is placed on the diagram. The arrows on the diagram represent the antifreeze/water combination that is called coolant from now on.
The water pump will pump the coolant throughout the engine passageways, circulating coolant around all the hot areas of the engine and extracting the heat from them and then sending the hot coolant through the radiator. The radiator sits in front of your car’s engine compartment and receives ram air as the car travels down the street. When you are sitting at a stop sign or a red light, there is a fan that draws air into the engine compartment through the radiator. When the cooler outside air is rammed through the cooling areas of the radiator, the air extracts the heat from the coolant inside the radiator, which cools the coolant down. The cooler “coolant” is then sent back to the hot areas of the engine again, to get more heat out of the engine. This is a continuous process and is very important to the life of your engine.
On some vehicles, when you turn on your car heater, a little valve opens and adds another passageway for the coolant to go, namely, the heater core. The heater core is another “radiator” of sorts. It sits in an area provided in the dashboard or firewall (engine compartment rear bulkhead). Most every car has a “fan” rotary switch with some kind of range of fan speeds provided. My truck has four speeds, the number one being the slowest. Regardless, the fan forces your compartment air through the fins of the heater core and then back into the compartment where you sit. As the cooler air from your compartment goes past the heater core cooling fins, it extracts the heat from the hotter engine coolant and sends it your way! Do you see where I’m going with this yet?
The thermostat’s job is like the thermostat in your house. It keeps temperature set to a certain value. In this case, it makes sure that the water temperature is maintained at the optimum engine operating temperature (195°F). With this kind of temperature entering into the heater core, it doesn’t take long for me to feel nice and toasty while driving.
When your engine is warming up, the thermostat closes off the passageway to the radiator until the water temperature is 195°F, then it opens, allowing the coolant to obtain cooling from the radiator. The thermostat opening can vary, depending upon the coolant’s temperature. I would hope that it is full open when the engine temperature is 200°F or more, wouldn’t you?
So, armed with all this information, what would be the easiest way to determine what the problem was with my daughter’s car heater? How about trying the most logical and cheapest things first? What I mean is that there are things you can do without the help of a technician (which always costs money). How about checking the fan first? Is the heater fan blowing air? If it is, then you can rule that out. Drive the car and check the operating temperature (if you have a coolant temp gauge in your vehicle). Break out your car’s operating manual and find out what the normal range of coolant temperature is. I’m sure it will tell you. It just so happened that my daughter’s car was operating at 90°F-100°F. This was a telltale sign. It could have been due to only a couple of things: low coolant level or bad thermostat; bad in that it was stuck open all the way at all times, never letting the engine heat up to 195°F. The coolant was not low, as a matter of fact it was the thermostat. She took her car to the technician and had the thermostat changed. If the problem ended up to be a heater core (clogged or dirty), the repair costs would have been tremendous. Thankfully, it wasn’t.
Conclusion: A decrease in airflow, or the absence of airflow is a problem with the air-moving device, i.e. the fan, sometimes called a blower motor. The absence of heat is usually a problem with the source of heat, i.e. the engine coolant, AKA antifreeze. The antifreeze is not hot enough to transfer sufficient heat to the cabin, or there is insufficient antifreeze, or the heater core cooling fins are clogged. It is rare that the heater core itself is the sole conspirator in your car heating problem. Check your antifreeze quantity first; if it is fine, you will have to take your car to a trustworthy technician, unless of course you can take care of the repairs yourself. Our video [1] “Basic Car Maintenance For Pretty Hands!®” provides some tips on how to choose a reputable automobile tech and demonstrates how easy it is to check your engine coolant. Give it a try!
Craig
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