Five Signs That Your Car Has a Bad Heater Core
Heater Core, O Heater Core ... Wherefore Art Thou, Heater Core?
You might be wondering what the heck a heater core is, what it does, and how it can affect your vehicle. These are all great questions, and we’re going to get you some quick and easy answers so you can get your car fixed ASAP.
What Is a Heater Core?
It’s part of the car’s cooling system. It looks exactly like the mini-me version of your radiator, and is, in fact, a small radiator itself, with a grid of little tubes and a waffled appearance from the fins that disperse the heat. Your heater core allows your heater and defroster to function.
What Does a Heater Core Do?
Your heater core circulates coolant through the little tubes; the coolant comes in through one heater hose and out the other, radiating heat into your cabin so you don’t freeze on those cold winter mornings. It's also responsible for allowing your defroster to function properly, and it's linked into the air conditioning system, which is organized around similar principles.
Where Is the Heater Core Located?
Your heater core is usually behind your dashboard, under the center or the passenger side. It will have some sort of casing or housing and is usually buried behind almost every other component of the dashboard.
How Do I Know If My Heater Core Has Gone Bad?
I'll give you five clues below that will help you decide. Diagnosing a bad or blown heater core is pretty easy. Replacing a heater core—maybe not so easy.
Note to Readers!
You might experience only a few of these symptoms of a bad heater core, or you might experience all of them at once. A lot of this depends on your vehicle, it's age and the state of your vehicles health at the time when your core goes bad.
1. Is It Foggy In Here?
The most common tipoff to a problem with a heater core is when the inside of your car suddenly fogs up for no reason. And when I say "fogs up," I'm not talking about a little mist on the edge of the windshield, I'm saying every window is covered with moist, warm condensation.
What may have happened is that your heater core blew while you are driving, after the engine warmed up. The warm coolant leaking into the cabin of the vehicle caused fog because that coolant was previously sitting inside a warm and temperature-regulated coolant system, and now it's evaporating into steam as it hits the cooler air inside your car.
2. Do You Smell Melons?
Whether or not the car got all foggy when the heater core broke, an unmistakable sign of a leaking heater is a fruity, sickly-sweet smell inside the car. This is the smell of your radiator fluid and definitely a sign that coolant is leaking into your car.
You might also smell this lovely smell around the outside of your car, which means it's time to look underneath your vehicle and see how much of that coolant has spilled out onto the ground.
3. Your Car Is Rather Thirsty
If you find your car, truck, or van has suddenly developed a voracious appetite for coolant, and you cannot figure out where it's all going, you may well be looking at a blown heater core. Sadly, if the leak is hard to find, the reason may be that the coolant has been leaking into your cabin when the system is cold, and instead of making fog it's creating a puddle. The first place I usually check to confirm a bad heater core is the passenger-side floor. If it is soaking wet, and so are any forgotten shoes or fast-food bags lying around down there, then I know to suspect the heater core.
4. Brrr! It's Cold in Here!
A chilly passenger compartment is not always a sign of a faulty heater core. It may indicate that your blower motor or another component of your heater has gone bad (cheer up, it may be a component that’s less tedious to fix than the heater core). Though if you're seeing one of the other signs in additiion to a lack of heat, that's a pretty good indicator that the heater core itself has a problem.
When a hole or puncture develops in your heater core, all that warm air may escape too quickly to reach you at the other end of the heater ducts. Depending on the size of the puncture, you might feel mildly warm, lukewarm, or absolutely freezing air coming from your heater.
5. Cold Cabin, Hot Engine
If you find that your vehicle has overheated, or continues to overheat, you'll want to check on the health of your heater core for sure. Bear in mind though, that many other parts of the car could be involved in the overheating. If your heater stops putting out heat, and your engine seems warm, investigate whether there is a coolant leak elsewhere, or some other issue with your car.
Overheating is very serious for your car. All sorts of major components of your car will wear and break down in record speed when they get too hot. If your car overheats, investigate the problem and get it fixed ASAP. If the temperature gauge goes up into the danger zone, don’t drive it; tow it. You don't have to heed my words, but I can guarantee you'll learn a hard lesson if you don't.
Signs of a Bad Heater Core
More Diagnosis: Testing the Pressure in the Cooling System
How Do You Change a Heater Core?
This job is way easier to describe than it is to perform. So, often a DIY'er will check out a Chilton's Manual or other auto guide and say, "No problem! I can change a heater core!"
I'm all for this kind of enthusiasm; it's how I myself got into changing heater cores. Though let me forewarn you that it is a very tedious task, and once you know how to do it, all your friends and family will want you to change theirs too!
With that warning out of the way, I'm only going to give you a very basic guide for most cars and trucks from 1958 to 2010. For the details for your particular vehicle, you'll need to do your own digging.
Does This Look Like Fun?
How To Change a Heater Core
1. Disconnect the battery.
2. Remove the steering wheel from the vehicle.
3. Remove any outer doors or casings from things like the fuse box, speakers. and kick panels.
4. Remove the glove box, radio, speakers, and any accessories.
5. Remove any gauges (be careful if you have a speedometer cable back there!).
6. Detach and remove your heater and air conditioner controls.
7. Unbolt and remove the dashboard.
8. Do not disconnect your air conditioning unless it's absolutely necessary and only if you have the proper means to dispose of the Freon. Do not just let it leak into the air. It is bad for the ozone layer and is toxic, especially to people with heart conditions.
9. Disconnect the two heater hoses from the engine compartment.
10. Move any air ducts or other components away from the heater core housing.
11. Remove the heater core housing and set it on a table. Remove any screws or fasteners to gain access to the heater core.
12. Take the old core out and put a new one in!
To install your heater core, just follow these instructions in reverse. If anything got broken on the way out, please make sure to replace it on the way in.
As with most DIY tasks, you take on this one along with all the risks involved. These instructions are very basic and meant for a person who is already very mechanically inclined. If you don't have appropriate tools, safety knowledge, and a strong mechanical aptitude, you'll want to seriously consider taking your vehicle to a garage to be fixed by a professional.
Share Your Experience, Or Ask More Questions
I love to hear old heater core job stories. They can be epic battles, depending on what kind of vehicle we're talking about. If you leave me a question or a story in the comments below, please tell me the year, make and model of your vehicle.
Questions and Answers!
You're looking for answers, and I'm looking to give you answers! So, you ask them in the comments below, and I will answer them as quickly and as accurately as I can. Please keep in mind that the more details you can provide about your car and your problem, the better quality advice I can give you.
Also, if you're question is not answered in this hub, please check my other articles, as I might just have created a whole new hub with your question in mind!
Yes! It's definitely possible
There are plenty of times when heater cores will go bottom up, and only barely exhibit one or two symptoms. In 90% of cases, you're going to clearly experience at least two or three signs that give away the culprit.
In you're particular situation, especially without any loss of coolant, while I wouldn't rule out a bad heater core, I would look first towards your air conditioning unit. While it's not unusual for an aging vehicle to take a little time to blow out crisp and cold air, if your a/c is on the fritz, it could also be the culprit soaking your passenger side floor. Alternatively, you could also have a leak in the seals around your door, windshield or firewall -- all of which could be soaking the floor as well.
Question: Is it possible to have a broken heater core and NOT exhibit each of the signs?
I own a 2005 Honda Civic. Lately, my a/c has been on and off running Lukewarm and as I gain speed, getting colder. My passenger side floor HAS been thoroughly soaked but not recently. However, I have not had any problems with coolant being low. No overheating. I'm certainly NOT a mechanic...I'm a female. I get in and drive. If it needs gas I fill it up. If it needs oil I get it changed....that sums it up.
Is it possible to have a broken heater core and NOT exhibit each of the signs?
Yes... and No...
To answer your question in general, Yes -- it's not unusual to smell a bit of residual coolant drying up in the system.
That being said, it's not normal if this smell persists for more than a few days of driving. So, in greater detail to your individual plight, since you are describing a chronic type persistence in this smell, I would urge you to take your chevy back to the mechanic and have them check for any small leaks if your coolant system. While it could just be some residual coolant, it's more likely that there is a small leak somewhere that wasn't caught originally, or that occurred after your last heater core was replaced. It's not unheard of for this to happen, especially if your vehicle experienced an overheat or any serious pressure in the coolant system when the heater core went bad.
Still smelling coolant, is this normal?
Just bought a 2008 Chevy equinox. That same day I could smell antifreeze while the heat was running. So I took it right back and they said bad heater core. I got it back today, heat works great! But...I can still smell a very slight scent of antifreeze. Not like before and it even seems to lessen as I drive. But when I restart it I smell it again slightly. Could this just be normal after having one fixed, maybe there's a residue in the vents or something? I'm hoping it just goes away after a day or so. Opinion?
The Price of Heater Core Replacement
This is a difficult question to answer, only because it depends on what country and/or state you live in, what type of mechanic you see and what type of vehicle you drive.
That being said, I can offer a ballpark idea of what I might charge and what common prices are found in my area (Seattle, Wa).
For me, a heater core is often a large job, not because it's difficult, but because in nearly all vehicles, the heater core is behind the dashboard. So unless I have direct experience with a particular year, make and model that I've performed this on, my initial assumption is that it will take no less than 8 hours to disassemble the dashboard, retrieve and replace the heater core and then reassemble the dash around it again. This is a general time estimate, including most newer cars that usually have lots of delicate electrical elements, clips and knucklebangers. As a mobile mechanic, my usual going labor rate was $60 an hour. So a general estimate for a heater core would be around $480.
Now, shops in the area, who often have more specialized tools, lifts and predictable work environments, can often get the job done in half the time. Though because they are running a business, they're shop rates are going to be higher -- $90 to $150 average. So for a 4-6 hour job in a shop, you're looking at a minimum of $360 to $600, plus the price of their preferred manufacturers heater core.
How much does repair of the heater core cost?
I am positive I have a heater core problem. Ironically, I started the day I got my car back from getting a fuel pump relay repaired. After paying a lot for the fuel pump relay, how much does repair of the heater core cost?
Pipes to Nowhere...
Okay, I first have to thank you for sharing this complication. To tell you the truth, without being able to stick my head under your hood, it's a little bit difficult to narrow down what you're seeing precisely. That being said, from your information, I would suggest that it's likely that your disconnected 'pipe' either used to be connected to your heater core as a part of the inlet hose.
Your heater core is a really basic set up. You have your main radiator in the front of the car and two hoses (it's not often that they are pipes, but it's not unheard of), an inlet and an outlet, that connect to the corresponding pipes attached to the heater core. These pipes will often protrude from the fire wall, which is where I suspect you're seeing this "pipe to nowhere".
Where's that leak coming from?
I own a 96 chevy corsica 4 cylinder. 2 days ago, on my way back from work, I smelled a very sweet humid icky smell (coolant) inside my car. I kept driving only to see that white smoke started coming from my vents and my car started rapidly overheating. I pulled over to let the car cool about 6 times on the way home. When I got home, I looked under the hood and seen alllll of my coolant was gone after just getting it filled 2 weeks earlier. I asked around and everyone kept telling me HEATER CORE HEATER CORE HEATER CORE. But everyone also kept telling me to look for the missing coolant on ypur passenger side floor. Its STILL DRY. I jacked up my car to find a leak and poured a gallon of water into the coolant compartment to do just that and quickly jumped under the car. But what I found was all of the water was pouring out thru a 1 inch pipe connected tp absolutely nothing right underneath the heater core. No leakage from actual core itself. I was wondering if you could tell me if that is still a heater core problem or something else before I start tearing my dash apart? Please and thank you. :)
Bye Bye Heater core...
I have to say, while I'm sure they meant well, it's sure naughty of your friends to assume that a+b always equals c, when it comes to cars. I'm no master mechanic, but out of everything I've learned, and that all other mechanics I know have learned, it's that vehicles don't always act the way they are supposed to. In fact, I'd imagine that 90% of professional repairs could be handled by any old monkey with a wrench, if it weren't for the fact that cars and trucks are like 5 year olds. Sometimes they are straight up text book, sometimes they do something completely bizarre and unexplainable, and you find out that it's something super easy and right in front of your face.
When it comes to heater cores, it's extremely common for them to leak out into your passenger compartment, because they are usually right up underneath the dashboard inside your car. Though the leak could be from somewhere else, such as the inlet or outlet hoses, where they would spill out onto the ground. If that happened, you wouldn't have your passenger floor soaked.
The same thing could be said about heater core's just "dying" without any warning. That is very common, though it's not because they're aren't any signs before hand, it's because most of us are too busy driving to notice the signs unless they stick out. So smelling coolant, could definitely be a sign that your heater core has a slow leak and may need to be replaced soon. That being said, it doesn't mean that it is your heater core. If it were me, I would use a coolant leak checking tool, or take it to a shop and have them use one. In the first day or two after having a radiator changed, it would be expected to smell a little bit of drying coolant, but a chronic smell every time you turn the heater on, shows there is definitely something worth checking out; before something just dies on you without warning.
Symptoms before the heater core goes bad?
My mom's car just got repaired because of either the radiator or the fan kept turning off. But now every time we turn the heater on in the car, it will be warm, but I can smell something sweet, like syrup almost. I was worried about it, but someone told me that it wasn't the heater core because it won't give you any warning before it damages and that the mechanics probably just accidentally spilled some antifreeze. I really don't know what to think.
Without knowing more, my initial suggestion would be to have your new heater core and thermostat checked out. In this instance, it would more likely be a faulty thermostat than a faulty heater core, though you won't know until you have them checked.
That being said, before going too much further, I would also check out the seals around your windows. It could be as simple as a seal leak that is allowing moisture into your car and preventing them from completely defrosting.
I have an 01 Malibu I've replaced the thermostat and the heater core thinking that would stop my car windows from fogging up but even after those repairs my windows are still fogging up.... What's wrong?