How To Unclog a Heater Core - EricTheCarGuy

Heater problems in the winter suck. But with a little diagnosis you can usually figure out the problem. Heater cores can get clogged from time to time and this video presents a solution to that problem should you have it. BTW, the product used in the video was CLR. If you KNOW you have a clogged heater core this procedure is a good thing to try to help fix the problem. However, if you are having heating problems I would suggest you check for air in the cooling system first before performing this procedure. The #1 cause of heating problems is actually air in the cooling system. More information on how to deal with HVAC issues can be found in this article I wrote.
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Due to factors beyond the control of EricTheCarGuy, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. EricTheCarGuy assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. EricTheCarGuy recommends safe practices when working with power tools, automotive lifts, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video. Due to factors beyond the control of EricTheCarGuy, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not EricTheCarGuy.

[@labradormcgraw2409]

This is why Eric's so popular on KZbin. He doesn't edit his vids to exclude any mishaps; we get to see everything - including the mistakes we all make. It also adds humanity to the channel - huge respect to Eric The Car Guy!

[@johnlumia6984]

So many wrongs in this video I would start with using a regulator set no higher than cap pressure. Too high and you burst the core. And never use CLR! Coolant systems need proper PH or all sorts of bad things will happen to block, head radiator ect.ect.

[@Liberty4Ever]

Most cooling systems run at 15 psi and the heater core won't be rated for much more than that so I would be very careful about using an air compressor unless I had a regulator set to perhaps 25 psi or less which isn't much air pressure. I would just flush it with a garden hose running very slowly. There are flush kits for that. There's also a radiator flushing chemical for $8 that I would use instead of CLR which could corrode the inside of the heater core and cause more problems later.

[@cronkthecrunk]

Man you are missing a special audience by not tagging "WJ", "grand cherokee" or "jeep" in this video... I'm over here watching chrisfix it and thinking "there's no way I'm getting at the ports by the fire wall" lucky for me someone mentioned your video in a 2 year old post in a jeep group lol

[@cameronkrider5341]

Thanks Eric. I have tried to reverse flush my heater core about 4 times over the last two years. I even used compressed air. It didn't work. I used your "certain product" and let it soak for about an hour before flushing out the heater core and now finally, after two very cold winters, I have HEAT once again.!!! Thanks for all your videos.

[@leedress2187]

safety glasses next time maybe? that stuff is bad for your eyes.

[@bigshortstack2929]

Eric, instead or CLR, use Brake Clean. Disconnect the hoses from the core; connect a hose to the bottom core nipple that is long enough to hang down below the engine and into a catch container. Then, spray the Brake Clean into the other nipple until the core is pukeing out nothing but the brake cleaner. This may take a couple of cans of the cleaner, but is definitely "cleaner" to use and less messy. This technique is very good for cleaning out AC lines, cores, condensers, etc.

[@lidabadery6834]

Hey bro CLR is not for aluminum. Better to use a flush+cleaner solution found in many local auto parts supply chain stores. Just fyi so you don't actually cause unwanted corrosion in your heater core. Only use Aluminum safe fluids to flush and clean aluminum parts. Awesome video btw, the air hose was a new approach in my book, only issue with that is the psi overload; heater cores have something like a 10psi max intake. Avoid using too much airflow.

[@kenwilks6289]

Thanks for this Eric! My son's 2000 Mitsubishi Eclipse was blowing cold air. I could hear the blend door moving, so I figured it had to be the heater core. That little trick with compressed air worked like a charm. I used duct tape instead, but I split it in half, so it was about the width of electrical tape. It also had a 170F thermostat, so I switched it back the the OEM recommended 180F. We have heat now.

[@Smiley810Jay]

I love maple syrup

[@deangeorge4982]

I have been on several DIY auto projects over the past 2 years. I haven't done this kind of work in 30 years. I have found that you have been the best at step by step instructions on the part(S) I am working on. I am going to try this on my 98 Honda Accord heater core as it barely puts out heat. I will post another comment once I am done. Thanks Car Guy!

[@wapman66]

You are my new favorite subscription. Thanks for being informative and entertaining. Seeing that you don't mind showing the slightly embarrassing stuff, is a testament to your character... sir. So you know, I checked out this video because of a recommendation from Todd Harrison. And I will highly recommend your videos to anyone else that is looking for automotive tutorials... and stay dirty.

[@DENicholsAutoBravado]

I came back to watch this video again. When I am worn out and tired, and feel that I have no need to learn I go back to an easy car subject, or to a video that I've already seen. You see, repetition is the key to learning. I love cars, so repetition doesn't bother me. EVERY time I come back and rewatch a video by this gentleman, I still manage to learn something. It isn't a waist of time like a rerun on television. :)

[@covinaca5312]

Ten years after this video was posted I used this method to fix my heater. I even spayed myself with dirty antifreeze. Thumbs up for saving me money !

[@Xtian62]

Eric, you just saved me many hours of work, and potentially many hundreds of $. Thank you for this. My 21 year old Honda CR-V now has heat, where it didn't before. I built a little rig with a valve and a pressure regulator for the compressed air. Worked like a charm. Thanks again.

[@ellenmcgarry6722]

I love the fact the you are human not a guy who pretends to be perfect. You show that all does not always go perfectly...Thank you...I will continue to follow your posts!!

[@vanrijn1669]

Following your great site for years. Thanks for showing us shade tree DIYers how things get done. Appreciate the fact you show us how things can go wrong since most of us have this happen even with our best efforts to avoid it. Thanks.

[@667crash]

Thanks to Eric The Car Guy!! I generally followed the process that you laid out with minor exceptions? I cut the supply and return heater hoses and bonded them together with a 5/8-inch splice so I could drive the car. I attempted to blow out the heater core and encountered significant resistance! OK!! I filled the heater core with CLR and waited 2-hours. I attached a female garden hose end to the return side hose leading to the heater core and drove to the local auto parts store where they have an exterior hose with 60-PSI water pressure. Turned on the water with a fairly instantaneous rush of water from the heater core that wasn't as dramatic as I had anticipated relative to color, but the volume was seriously dramatic. Put it all back together and how the heater works GREAT!! I seriously recommend following this guys general process. THANKS

[@tmartin67]

Thanks for the idea of using air to reverse flush the heater core. I used water before and had no luck. I used air, then filled with water and reverse flush with air for an entire gallon. Then the CLR, and reversed flush with air again, and did another gallon of water. I did this entire process three times. Then ran water reverse through so much easier. It just flowed! I now have heat in my car that I have not had for the entire three years I have owned the Jeep. Thanks again Eric!

[@shanereimer133]

Eric did you expect 12 years ago to be as popular as you are now?