How VW Parts Fail ~ Heater Cores 

I'd like to personally thank VW for taking a heater core and engineering a car around it.

Back in 2004 my wife bought a used 04 diesel bug from the VW dealer. The car was a awesome looking and my wife loved the look of it. But we didn't like all of the problems it had after we bought it. One of the problems was the heater didn't blow out hot air. My wife had a 70 mile commute to work one way so the heater should have started working long before she got to work. I thought right off the bat it was the heater core so I had my wife drop it off at the dealer to get it fixed because it was under warranty. A couple of days later my wife gets a call to pick up the car. When she got to the dealer the service writer told my wife "the mechanic wanted me to tell you that this car is a diesel and it takes a while for the car to heat up". That mechanic didn't want to go under the dash to change out what was obviously wrong with the heater. I think it would have been a different story if I dropped off the car instead of my wife. So when we dropped off the car the second time I went with her and I talked to the service manager about the crappy service they gave to my wife. I am a certified FAA power plant mechanic so I know right off the bat that the VW mechanic was lazy and full of crap. They took the car in again that day and we had the car back the next day with a new heater core and the heat worked perfectly.

I bought a 2014 Passat TDI with 59k miles and within three months I had to have a new heater core put in. Six months later another heater core, that one lasted eight months and had to replace it again. Each time the work was done at the VW dealership I bought the car from under warranty. After the third heater care I made the decision to trade in the car for a new Toyota. I do miss the great fuel economy of the TDI but but the poor reliability of that car wasn't worth the headaches.

Huge fan, humble mechanic! Thanks for all you do! I have 07’ gti and have learned that if I turn on heat before the car has reached normal operating temp., (190F) then I get cool air. To add to this- lately, the heat only works on the floor mode or the floor/ defrost mode. Reside in Texas, so it’s not that big of a deal- just don’t want other problems down the road. Thx again.

Interesting tip with CLR, thanks I will try that on my next flush. I enjoy your info on VW because I hate to help figure out or repair what may be wrong, I have had experiences and trust me, it never gets easier. Thanks again

Funny enough today I had a 2013 Skoda Octavia with a clogged heater core, seems to be a common issue with this generation, and looked like some sort of block corrosion for using just water that blocked it... very important to use the right coolant ... great vid 👍

You're right about heater core issues on the old Mk2s and 'Rados, if you ask any of the old heads someone always knows a guy that had the core leak or even explode in those cars. I've never seen issue in any of the Mk4 and newer but have seen the B5 and B5.5 Passat/A4/S4 have clogged cores.

Excellent video! I own am the proud owner of a 93 corrado and i believe mine got the heater core "fix" from the recall which was just a rubber step down placed inside of the coolant pipe so less pressure would be going through the core. Well the previous owner must have had a leak because the coolant lines were elbowed. I ended up replacing the core but out comes the entire dash and on a 20+ year old vehicle dash parts are a paint to take appart and reassemble and have everything fit nice.

6 years later... my poor MK3 Jetta now needs this transplant due to a brittle broken inlet tube.. woohoo! thanks for this video! maybe do a beer of the week?

Yup! On my 2013 Passat Tdi , check engine : code: P2457 EGR Cooler. Engine temp is normal, no overheating, just not blowing hot air Thank you sir!!!!

Love viewing the show all across the Ocean in little Belgium. Save on maintenance and you have a big job on hand. Don't forget to flush the engine and refill with proper G12 and PH neutral water. Keep up the good work.

Literally watched this video after getting my MKIV Jetta back from a leaky core... The struggle is real

I NEVER had heat on my 2013 Jetta GLI I bought the car new and I never remembered it having heat. Thank god it came with heated seats.

Firstly: I love your videos and attitude you have towards your profession. Secondly: I have a Skoda Octavia where there's a HUGE temperature difference between the cooling on the passenger side compared to the driver side. There'll be hot air blowing on the driver side, while the passenger side gets cold air. I'm assuming that isn't the heater core. On top of this my car uses an abnormal amount of coolant. I have had to refill five times since early September. There are other big problems with it, but it's driven 330.000km in 8 years. So I guess it's as expected :)

Over the years I found that even before the coolant appears underfoot I found that putting the defrost on blew wet air all over the wind shield fogging it instantly.

Hey H.M great video as always! I think I might be having this problem and I have one question, do these come with a flow control valve on VW CCs or fluid just keeps on circulating constantly? Trying to figure out whether the problem is within the dashboard or something under the hood. Thanks a lot!

Just did this on a 03 Passat wagon GLX 4Motion. I love this effin car. LOVE IT.. Winter coming in Northern Utah, so I gave it a shot. From zero heat (literally it was non existent) to blow you out of the car heat in 2 hours. Started with a flush, then a back flush got all sorts of big chunks out. Then added the CLR and let it sit for about 5 minutes, pushed the cle through with a little bit of pressure, and Wham-o.. Normal flow. Flushed and did the CLR 1 more time then flushed with clean water for 10 gallons after it ran clear, both ways. Then filled up the Core with some coolant (compatible) and tested it out. Unreal.

YESSSS!!! B5.5 video. Thanks dude. Probably doing this today. *fingers crossed*

changing the heater core on my b5 was my first ever DIY... apart from oil changes... boy, it was a mess, it took me 14 hours to do it and finished at almost 3am, i had a 200 mile trip the next day XD

I'm not sure how I missed this when you posted it. With persistent low passenger side heat, I took my 2014 Passat TDi with 56k miles to the dealer today. I'll bump this old comment thread to say that I now how parts fail firsthand. They were not surprised when I described the problem.

This guy is so legit he is in the corporate training videos for Volkswagen if you work for a dealership

Thank you for this nice tutorial I have a question what is the temperature of the hot air coming out from radiator ?

Speaking of the Corrado had my core split and dump lovely booking hot coolant onto my feet... I was so excited to do a 9 hour repair for 2 bolts and a $10 part... They really did built the mk2 platform around the core.

@HumbleMechanic, I had a problem with my heater last winter and I got the heater core flushed, and that fixed my heater problem. However, I'm having the same issue again, my heater barely works and I'm wondering if it's the same problem. Any help would be really appreciated :)

Our 13' TDI just popped that EGR Check Engine Light. OEM core on order.

This is exactly what happened to my MK6 Golf TDI. I thought the service advisor was messing with me when he said I needed a new heater core to fix an EGR cooler code. Thank God for the dieselgate warranty.

I've had a few VWs: 82 Jetta, 87 GLi, 85 Jetta, 82 Quantum, 85 Quantum, 03 B5.5. Change your coolant to something better! I've had excellent results with Peak Global.

smoking through the vents and top part of the fire wall under the hood. leaking hoses or failed heater core? iv alrdy replaced a couple other water system parts.

is it possible to move the dash forward on a golf 4 tdi 2004 like you did in the video to make the job go quicker?

Haha, I literally just buttoned up my B4 after replacing the heater core, and now this popped up recommended from RU-vid. Call me odd, but I actually prefer pulling the dash; gives me a chance to tackle rattles and latent wiring issues. :D

Hey! My 2004 Volkswagen GTI has a strong smell of coolant when the heat is on. The coolant level is stable, however, and my carpet doesn't get wet. I had a problem with a nipple on my reservoir firing coolant into my cabin filter, but I've changed the filter and used a heat vent cleaning bomb. I'm now looking at the liqui moly heat vent cleaner. It still smells. Do you think it could be a clogged core?

outstanding!

great video. I just did a flush on my 02 passat wagon that had "survivable" heat at higher RPM, very little at idle. Used the CLR, and an OTC blast vac , combo air (30 or psi for short bursts) and water. lots of junk, mysterious things came out lol. Heat is so far fantastic about 150 degrees from vents

Thank you.

My heater blows cold air when the temperature outside is like 20 to 30 degrees. Only the driver side vent blows warm air versus the other vents are cold air. Not sure if needs flushing and a dealer mentioned it’s the temperature blend actual. Let me know your input thanks.

why not putting a coolant filter like the big trucks have? you can install it as a bypass system. That way the heater core, egr cooler etc will not clog and just replace a $2 filter instead of that huge mess of replacing the heater core.

Once doing a complete coolant flush, is it possible on a MK4 golf to reverse the pipes to the heater matrix so it now runs in reverse or do they only operate one way round?

In the video at 7:00 you show accessing the heater core from behind by removing the dash assembly as one unit. However, I need to replace a leaking AC evaporator, which will require some HVAC disassembly. Is it possible to remove or disassemble the HVAC unit from behind with the dash out as shown at 7:00 or are there bolts holding the HVAC in that require front console disassembly in order to access them? Any advice greatly appreciated.

B5.5 Passat owner here.. got plenty of heat but a smell of coolant and lowered coolant level only on the coldest days, as in 15 F or lower Is that still indicative of a leaking core or could it be something else?

Could that cause a build up of coolant pressure and make a line blow or spring a leak? Or thermostat fail?

I have a 2013 VW Passat TDI. I had one heater core replaced under the TDI warranty in 2018. Heating & Defrost issues have returned. Is there a way to flush the entire system of the aluminum rust caused by the DEF mixture from DEF tank to Heater Core? Drain tube clog? Blend door, Door motor, Actuator,...etc? Is the dual climate control mod a possible culprit as well?

Can you make a video on installing an auxiliary heater? I saw a tutorial on installing one in a GTI on a forum somewhere. It takes too long to heat up in Canada using just the engine heat.

I need to know if the heater core being clogged will make my mk5 over heat

For a '99 Cabrio 2.0, what should the normal interior cabin heat reach in F degrees? My heat doesn't get much warmer than the cold air outside.

Just purchased a 2001 1.8t pass at yesterday. Temp never came out of 130 degrees range driving on highway. Heat was ok but not hot. When I went into street traffic, heater and higher. I think either thermostat is stuck open or no installed. Watching your video I see it could be a chain reaction of heater core etc.

Hi bud. My b6 VW Passat 1.9 TDI has a coolant leak for months that no garage can find. Coolant leaks from the bottle but no visible leak anywhere. Possible head gasket but the car is driving perfect. Also heater blows hot and cold air when it feels like it. Could the thermostat cause coolant to leak mysteriously and affect the heater from working and if I replace the thermostat could that fix the issue?

Can you do a video replacing a heater core on a mk6????

Thanks a lot for your advice. I used CLR is the best solution, use it with no hesitation!!

we have done a ton of heater cores in ' 13 and some '14 passat tdis in the past few months. the 03 passat was an all day repair.

Great video ... thank you for the detailed explanation. I have a 2000 Jetta (AEG) that is getting the "sweet smell" in the cabin, foggy windows and wet floorboards. I still have heat though that works just fine. I am loosing coolant slowly which may be related or could be elsewhere. Think it's a clog or a leak?

I have a question: the air blowing is somewhat lukewarm, when i put the blower on heating, the inlet to the heater core is very hot, the outlet is somewhat cold to lukewarm, when i turn the heating off then both inlet and outlet are hot, does it mean the core is clogged? Or do i have another problem?? I checked the flap motors on both sides and i can see them both moving, i even did the relearn trick. What could be the problem? Thermostat seems to work well, the car heats up quickly and does not overheat. Jetta mk6 1.4tsi. Thanks!!

Had my heater core replaced in our 2009 VW CC about 2 years ago with original parts (supposedly). Seems like now I have a weak heat in the passenger side again. Any idea why it would clog up (supposedly) again so soon? I wish there was a good video of how to flush the VW heater core on these.

What if one has the opposite problem, in other words you get only hot air inside the cabin? I am experiencing that issue. The section right above my radio get pretty warm. I measured it to about 107F today. Any suggestions what is causing that?

I got all the air out of my heater core and it worked for one day. not sure if I should flush it or is it something else. temp gauge climbs a little then drops back down and keeps doing the same thing. is that a thermostat.

I get a whiff of antifreeze when I turn it from cold to hot, but it only lasts for about 1 second. Would that make sense for a heater core leak?

I just made with my like the 1000 likes, very very good video, thank you very much for the information

Not only temp faults on cjaa but also a fault for coolant flow. I have a mk6 Jetta that had a stop leak put in it and heater core is plugged and fault I got was egr cooler insufficient coolant flow

How about a car design that is like this. Having a rectangular shaped door in the firewall to gain access to the heater core in order to service it? But most cars have the engine bay full of stuff. Some old cars have some space there.

Hi there quick question. Do you have to remove the whole dashboard on the vw polo 1.9 sdi 9n? Thanks

Can a bad heater core cause a P0401 “Insufficient Flow Detected” for the EGR in a 2014 TDI Jetta?

Where is the best place to buy VW Jett GLI heater core at? I see a lot of bad reviews on the Spectra 98120

My heater core in my 2013 VW Jetta GLI failed after 10 months but my mechanic is saying it is not covered under warranty because it wasn't installed at a dealership, is this true?? He bought the part from a dealership but installed it himself.

Never had a problem with heater cores on any of my air cooled VWs. Although they didn't have any heat either. After 37 years since my last air cooled I'm in my first water cooled VW MK6 GTI. Nice to have heat power & handling in a very comfy package. VW has come such a long way. Your video has scared me straight, I will be doing coolant service on my GTI at the appropriate time. Think I'll add a coolant flush to the 40K service. Thanks for another insightful video Charles. Knowledge is power.

My daughter just bought a beetle I can't remember if it's a 2000 or if it's a 2006 driving it around I noticed the sickly sweet smell when I put the defrost on. Does that automatically mean that the heater core is bad or could it just be clogged?

I got a used 2000 VW Passat wagon (B5) with a clogged heater core--because the previous owner used StopLeak. When I flushed the core and radiator, the radiator started leaking again.

Question in regards to heater control valve. 2015 vw golf 1.8L Replaced core and there was no coolant in it(thinking it was plugged) either way we put in new core and ran engine.. still no heat, no circulation still through core. Where is the heater control valve located in this vehicle? Doesn't look like it's in engine bay.

I have a 2000 VW Passat B5 wagon and have zero heat now. I was getting some heat but would take a while and now it just blows cold air, which sucks since here in Seattle we are into winter weather. I simply don't know enough to do a flush on my own as that more than likely is what needs to be done, wish I could find a fellow Passat owner here who has done this that could assist, as I don't think this is something a dealership would do, or one that I could trust to do. Great video by the way.

How does a shop charge to put a heater core on? I bought the 300$ one with metal pipes

My husband is trying to replace the heater core in my 2004 passat because it is leakikng. Do you have a video that shows how to no take the whole dash off or something that will help him all the video are different and yours explained it the best. Thank you your video was really good!

Firstly thanks a lot for all your useful videos. I need your help.I have totally cold air through the vents. - Inlet and outlet hoses on the heater core are hot the engine is at 90 degrees centigrade. - checked water pump and thermostade; both are OK - Air Condition OK. When AC is on, vents work perfectly - Bleded the heater core. - I worked the climatronic self-diagnose system. 25b error code (Footwell/Defoster Blower Vent-V85) but after resetting it disappeare again. I have problemonly with footwell vents as I observe when AC is on. I flushed the heater core only once in 25 years a few years ago when I had the same problem again but this time I hesitate to flush. As I read in the forms, flushing might damage a leak in the heater core. You know it may be so difficult and expensive in especially 25 year-old Passat B5 as the dash board might fall a part while trying to reach the heater core. My question is ; might the CLR chemical during flushing damage my 25 year-old heater core ? Thank you for your feedeback in advance.

My VW Jetta TDI 1.6 is taking too long to reach 90°c. Even if I reach 90°c it starts dropping as soon as I stop. It remains constant at 90°c if I drive constantly above 70KMH. The thermostat was replaced last year but I didn't get a chance to test it because it was already summer in Estonia but it's behaving same this winters in -ve temperature. What could be the issue?

I have an 05 mk4 Jetta gls and in the dead of winter after started for awhile it's still doesn't heat up. Now after sometime it's very hot. Is the time elapse showing that my heater core is starting to fail? It only has 106k?

On a 2004 Volkswagen Jetta TDI 1.9 can the heater core be changed without removing the dash?

good to have reminder about not polluting waterways and rivers with old coolant..... also at same time complicated to dispose of it safely , in the UK at least : /

I have this problem on my 57 plate seat Leon Thermostat fixed Blowers fixed, resistor blew out 🤦‍♂️ Gets to temp, blowing freezing cold air 😩🥶 I’ll have a chat with the mechanic in the morning then.. They didn’t seem to lean towards this thought for some reason when I was last there.. 🤷‍♂️

How much does it cost to change front heating defrost main ducting replacement on a 2007 vw beetel 2.5

My mk4 jetta tdi has a failing one I believe. It's blowing hot air but it smells sweet and the windshield and side windows are getting coated in what I believe is coolant. It's a nasty foggy film that's pretty difficult to get off the glass

may be will check the cool-heat flap mechanizm!

The issue I am having is that after my car went for a car wash my heater stopped working, the next day I noticed some water (because it doesn't have any smell) on the carpet on the passenger side and the blower motor has stopped working on any settings. Now I'm not sure if it's just the blower motor that's defective or is it also heater core? Could the water pressure from the car wash leaked inside the cabin somehow and shorted the blower motor? Is there a chance once the water is dried up things will go back to normal or should I be replacing both the blower and heater core? any help would be much appreciated. Thanks.

Hello.I have skoda octavia 3 and i put G12 coolant and not G13..Its ok???My mechanic say that make the same job...And G13 have different systatic for enviroment.Thanks...

Be great to see a dash removal... one of my pipes in the enine bay to the heater core got a leak in it... super...

Charles first TY for your awesome Vids! I recently bought our first VW a 02 Jetta TDi. We LOVE this car! Steering is soooo tight and responsive, drives smooth dead straight down the road for mile if the road is level! I have 2 questions if you could please let me know privately or publicly I don't care just really need a bit of direction. Our heater core is leaking I smell it when the heat is on no steam yet though. 1. When I replace the heater core what is the BEST brand I can use I don't want to do this 2 times. 2. Is there a tutorial that you know of for moving the dash out enough to sneak/squeeze the HVAC box out? Our car is old and brittle from Texas heat and I would like to preserve it as much as possible. THANK YOU again for the informative videos. I subscribed as soon as I bought our Jetta.

Anyone know of a video or a forum that can show you how to pull the dash away from the firewall as he described? Thank in advance.

Bought my 2014 TDI Passat with 40+K mi. it's now at 70K. I love the car but am more than disappointed at having to replace the heater core twice in less than 30K mi. since I bought it. VW did both replacements under warranty but I am very nervous about keeping the car for its fourth core. No leaks, just crude. I never drive less than 10mi. If that's the pattern, it seems like I'd need to flush every 20K. Seems extreme. The dealer says it's not uncommon and VW is still looking for a solution.

any tips on how to separate the heater core from that stubborn pipe??????

My Mark 7 Golf takes a long time before the heater core produces hot air. No error codes for thermostat, coolant level is fine, and pipes to the heater core are warm after only 5 mins driving.

I’m replacing this on a Skoda Octavia 1U now, and I can tell y’all this is a painstaking process that will take around 8-14hrs to do unless you are a real professional mechanic. (Breaks not included).

Thanks man, looks like the dash is coming off

I have a 2015 vw Passat and the left side gets hot but the right side most of the time blows cold, what do you think is wrong with it?

hello very good video 👋👋 in vw golf mk2 do I need to remove all dashboard to change heater core ? I have very weak heat (air pressure ok) u mentioned thermostat can do such problem also I have put water in heater core it's return pipe flow is full and not clogged any help will be great it's winter here and bitter cold

Open flame? I thought that was in the Messerschmitt Me-109?

Is it, at all possible for there to be a hose leak? In other words, is there something else i can try to do before i accept the fate that is replacing a heater core?

Whats the difference between orange coolan an green coollant.

I'm wondering if a DVD is available for DIY heater core replacement on the B5 ? Thank you.

Is it really expensive to have that done if you have to have your whole dashboard taken out? it's a 2003 V6 Passat. I'm pretty sure that's what's going on with mine?! ( heating coil) problem

Adding a electric heater is a good option?

7:02 I’m wondering if that would’ve made the job any easier for me on my old 97 A4. I did that job about 3-4 years ago on that car (sold it :( ). I went the whole Colorado winter without heat, spring time I finally did the heater core job. It was a complete PITA if you ask me. Then I found out my AC compressor was blown when I had to have the system vacuumed out beforehand to do the job. It sucked. So I didn’t have AC all summer. Lmao. Never again did I want to do that job. Luckily the core lasted my entire owner ship. However let me tell you that car was not friendly what so ever with coolant issues. Man. One thing after another. The day my 04 A4 quit putting out heat I was so nervous this was my fate again. Luckily I was able to achieve a fix via a flush using a $8 harbor freight fluid transfer pump and a $4 coolant flush bottle, big bucket and some water. Worked like a charm. Sold that car recently. I’m now in a 2013 Passat TDI, got in on a CPO, the day after buying it I brought it back to the dealer for a heater core replacement. Luckily, covered under the CPO. Just now realizing every German car I’ve owned has had a heater core issue. Lol.

only found this youtube channel recently. but its fast becoming my favorite, even though i have not owned a vw in years. and final piece of brownnosing you have an epic beard. Ho do you get your wife/gf to allow it?

Could a clogged up heater core cause the car to overheat? I have been overheating on my 2005 Passat 1.8 and after changing almost every hard part, I bypassed the heater core and now I am not overheating. Yes, I have bled it properly multiple times, including vacuum bleeding it thoroughly. When I put the heater core back into the system it overheats again.

If the core goes bad will sound like loud popping noise and steam rising everywhere or would possibly be the hoses leading to car. Had water around the hoses leading to the core.