Heater Core Basics
One reason for having some understanding of what your heater core is and how it works is that it can act as a warning that something is seriously wrong with your car that could be detrimental to engine life.
A second reason is that there are some simple maintenance tasks you can perform, but more importantly, there’s a good reason why heater core repairs can sound outrageously expensive enough to sound like a scam…but in many cases are not.
The first reason explained: According to the Haynes manual website on the basics of your car’s heater core, it helps to think of your heater core as a second smaller radiator.
“If you imagine that a heater core is pretty much a smaller version of the radiator that’s out front in your car, then you won’t be far wrong. However, instead of being used to cool the coolant in the engine, it uses the heat from that same coolant to warm the car’s interior. It works, in essence, by diverting coolant from the rest of the car’s cooling system.”
In other words, it is a useful way to take advantage of the thermodynamics occurring within your cars antifreeze/coolant system to perform multiple functions.
What happens is that as a running engine builds up a lot of excessive heat, the antifreeze/coolant running through the block absorbs that excessive heat, which is then actively pumped to the radiator where it is cooled by air passing through the radiators vents that draw heat from the radiator like heat sinks dissipating heat to the surrounding air. Key to controlling the temp of the circulating antifreeze/ so that the engine is neither too cold nor too hot is a special valve referred to as a thermostat.
When you turn on the heat inside the car, another type of valve is used to direct hot coolant flow to the heater core (on some vehicles), “…or a door is opened to direct air through the already-hot heater core.”
Haynes’ points out that the simplest systems (found in older models) moderate the temperature by mixing cold outside air with hot air from the heater core.
More complex heating/cooling systems have dual-zone climate control systems connected to the heater core(s) that allows passengers to control the heat settings in their immediate environmental airspace.
Warning signs of problems you need to know: (1) If your engine has fully warmed up and you are driving down the road and find that the heater is beginning to blow cold air rather than the warmed air you expect, then your car has most likely developed a leak and is losing its antifreeze/coolant. (2) If under the same driving situation, you find that the heater suddenly blows cold and the engine’s temperature starts to climb dangerously high, Haynes warns that the belt that drives the water pump (or the pump itself) has most likely failed.
The point to understand is that if either case occurs, you should stop as soon as is safely possible and switch off the engine to avoid causing permanent engine damage from overheating such as warping of the cylinder heads.
The second reason explained: Although typically a maintenance-free part of the car, heater core hoses should be checked twice a year for cracks and leaking. And if you do have your coolant replaced every 30,000 miles don’t forget to have the heating system running to flush new coolant into the heater core. Refer to a Haynes manual for some excellent step-by-step instruction on how to save money doing your own coolant flush.
The caveat to DIY repairs involving your heater core is that there is a reason why garages typically charge a lot to replace a leaking core or why some may even refuse to do the job at all! And that is because it often entails removing the dashboard and everything connected to it just to get to the heater core. In other words, it is a complex and very labor-intensive process.
Not only do mechanics hate the time-sucking process that it takes time away from other more profitable jobs, but there are so many clips and screws and other connectors that typically have aged and are brittle and tend to break making the job harder to complete and in a timely manner.
That said, the Haynes manual has step-by-step details on how to DIY but be forewarned this is almost never an easy repair job to take on.
For additional news related to automotive repair, here are a few articles for your consideration:
• Car Owners Who Don’t Pay Their Car Repair Bills
Timothy Boyer is a Torque News automotive reporter based in Cincinnati. Experienced with early car restorations, he regularly restores older vehicles with engine modifications for improved performance. Follow Tim on Twitter at @TimBoyerWrites for daily new and used vehicle news.
COMING UP NEXT: What to Do About Excessive Oil Consumption in Your Car
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