How to: Replacing 2012+ NMS Passat heater core

767wrench

Veteran Member
Joined
Jul 25, 2012
Location
Ohio
TDI
1981 Rabbit Pickup
My 2012 passat unfortunately had the clogged heater core issue. At first I thought it was going to be very costly or labor intensive to fix but after some research it turns out its not a dash out procedure on these cars and is actually relatively easy and cheap to do yourself. I did mine start to finish in about 3 hours.

Heater core PN: 561819031B

Seals and clamps PN: 561898380

Car was at 77,000 miles. Build date 04/12. Climatronic dual climate control. G12 coolant was the factory fill and had only been serviced with G12 until now. The core is clogged with thick white buildup. It may be white rather than the pink that some have reported because I flushed it before removal.

Buildup on the inside of the tank


Buildup inside the tubes. We scraped some of it away before this pic to see what it was.


Discoloration of the lines compared to new


A few pics of the removal. The trim has one torx screw and then drops straight down and out


The storage compartment is removed to access screws for the under dash panel. I just pushed in on the sides to get the tabs past and then it rotates down and comes out. It took some force but I didn't see another way to remove it easily.


The under dash panel has a few screws to remove it. The data link connector needs removed. There are 3 clips on it to depress from the back side. The foot vent can be removed after the panel it has a few torx screws.


This panel covers the heater core. 4 screws remove it


The core exposed. Remove the clamps and pull the lines apart. This was the hardest part. The manual tells you to loosen the 6mm screw that is in between the heater core lines under the hood. It is recessed in a hole between the coolant lines. It must aid in allowing you to move the lines off of the core. It was still tough to do even with it loosened. The bolt is somewhat hard to get to under the hood. I left the lines under the hood hooked up and just drained the coolant at my block heater because it was a lot easier than messing with the lines at the firewall. The pipes leading to the core stay attached and the connection is made where you see the clamps in the pictures. Make sure not to cut the new o rings when trying to reinstall the lines. I bent the lines on the old core to remove it but the new one took more patience as I didn't want to bend it much. The flanges on the pipes kept wanting to cut the o rings as I worked the heater core lines past each other. It would be wise to do a leak check with engine running before reinstalling the trim.

A tip to get the flanges fully seated on the heater core so you can install the clamps. I went under the hood and pushed firmly multiple times on the hose connections to try and seat the pipes onto the core. I also took a rubber mallet and small piece of wood and was able to catch the rib on the line to knock it into place. The lines in the car just don't seem to give a whole lot. Just be very careful not to use too much force when "forcing" things! The lines are just thin aluminum after all!

The core removed. It pulls straight out once the lines are off. I didn't get much coolant out of the lines after I drained the car. This catch can was plenty large enough. Cover the area with rags to catch any other spillage when pulling apart the lines.

Info note: the electric auxiliary heater grid sits directly in front of the heater core and slides out like the core.

Heat works great with the new core. Both sides are HOT on Hi setting and high blower. Decent heat starts being produced with the engine at 145 degrees
I was able to find the core for $74 and the seals for $14 although you could probably reuse the clamps and o rings if you had to. I purchased mine from ecs tuning.
 
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gforce1108

Top Post Dawg
Joined
Aug 2, 2006
Location
Newburgh, NY
TDI
04 Jetta GLS BEW, 14 Audi A7 V6 TDI, 13 Porsche Cayenne V6 TDI
Very cool - they used the Audi design. I just did a Audi A4 last weekend with the identical setup. Did you have to remove the throttle pedal? I didn't get a single drip because I disconnected the hoses in the engine compartment, and cycled blowing air and flushing with water.

It was by far the easiest heater core I ever did.
 

goldgary

Well-known member
Joined
Sep 16, 2008
Location
NH
TDI
2012 Passat 6M
symptons please

Just wondering what the symptoms were, that you knew heater core was plugged. Or was it as simple that no heat was coming out of car at all.

I would think it would change so slow over time, that you wouldn't notice a big change.

Thanks, Gary
 

FahrvergnügenVA

New member
Joined
Jun 22, 2015
Location
Mechanicsville, VA
TDI
2013 VW Passat TDI SE
Just wondering what the symptoms were, that you knew heater core was plugged. Or was it as simple that no heat was coming out of car at all.

I would think it would change so slow over time, that you wouldn't notice a big change.

Thanks, Gary
My heat worked awesome up until the day I noticed it. The driver's side has adequate to good heat, while the passenger side has very cool, if not cold air coming out. It is easy to notice when you are running Defrost on the windshield, which is what tipped me off to the issue with one side clearing and the other not clearing at all. There is no doubt when it occurs, it is very obvious with the temperature differences. I also used the Vag-Com to check the actuator doors last night which operated as normal.
 

767wrench

Veteran Member
Joined
Jul 25, 2012
Location
Ohio
TDI
1981 Rabbit Pickup
Just wondering what the symptoms were, that you knew heater core was plugged. Or was it as simple that no heat was coming out of car at all.

I would think it would change so slow over time, that you wouldn't notice a big change.

Thanks, Gary
It was a gradual loss of heat for mine. First winter was fine, 2nd was ok but took longer to warm up the cabin when extremely cold out (0 degrees) . 3rd winter I installed a frost heater and grill covers. Even with all that when it was under 20 I still froze until the car reached full operating temp and had to run the blower on half speed for warmth. This fall it got in the 30s one night and the car was fully warm and the vents were blowing cold on the passenger side and lukewarm on the driver side. It was slightly better when driving and at idle they both went cold. Now that it's fixed it's obvious how bad it got over time. If it wasn't for me reading about this problem here I probably wouldn't have came to the conclusion it was plugged with it being so new. My windshield would fog uncontrollably too sometimes in the fall when first starting to drive. No matter how much cleaning I did of the windshield it still did it. Maybe it will be better now time will tell!
 
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767wrench

Veteran Member
Joined
Jul 25, 2012
Location
Ohio
TDI
1981 Rabbit Pickup
Very cool - they used the Audi design. I just did a Audi A4 last weekend with the identical setup. Did you have to remove the throttle pedal? I didn't get a single drip because I disconnected the hoses in the engine compartment, and cycled blowing air and flushing with water.

It was by far the easiest heater core I ever did.
Throttle pedal stays in place! Very easy job. I did a dash out on a late 90's cavalier once and I swore never again! Seemed like I broke 90% of the plastic I took apart and it seemed like it would never end!
 

gforce1108

Top Post Dawg
Joined
Aug 2, 2006
Location
Newburgh, NY
TDI
04 Jetta GLS BEW, 14 Audi A7 V6 TDI, 13 Porsche Cayenne V6 TDI
Throttle pedal stays in place! Very easy job. I did a dash out on a late 90's cavalier once and I swore never again! Seemed like I broke 90% of the plastic I took apart and it seemed like it would never end!
I've done a number of different cars. A Volvo 240 was one of the worst - after removing the dash I still couldn't get to the core so I cut the top off of the housing, replaced the core and epoxied it back together.

Next was a MKIV Golf - bought it knowing it had a bad head gasket. Didn't know about the heater core. I'd do 2 headgaskets before wanting to do another heater core.

The Audi was nearly identical to the Passat (03 A4 1.8T) but the throttle needed to be removed and there wasn't a lot of room to slide the core past the brake/clutch switches. But still - so easy.

I haven't dug too deeply into this heater core issue - Can I assume it's only on the dual climate control cars? Now that I know how simple it is, I won't worry about it happening to mine (not dual zone). My antifreeze was also replaced once for AC repair under warrantly.
 

767wrench

Veteran Member
Joined
Jul 25, 2012
Location
Ohio
TDI
1981 Rabbit Pickup
I've done a number of different cars. A Volvo 240 was one of the worst - after removing the dash I still couldn't get to the core so I cut the top off of the housing, replaced the core and epoxied it back together.
Next was a MKIV Golf - bought it knowing it had a bad head gasket. Didn't know about the heater core. I'd do 2 headgaskets before wanting to do another heater core.
The Audi was nearly identical to the Passat (03 A4 1.8T) but the throttle needed to be removed and there wasn't a lot of room to slide the core past the brake/clutch switches. But still - so easy.
I haven't dug too deeply into this heater core issue - Can I assume it's only on the dual climate control cars? Now that I know how simple it is, I won't worry about it happening to mine (not dual zone). My antifreeze was also replaced once for AC repair under warrantly.
My antifreeze was replaced multiple times each time using g12. Once for a turbo replacement the dealer took out the radiator, once for an accident, once when I installed my frost heater. I would assume any vehicle using this core and antifreeze combination would be suspect
 

tdiatlast

Top Post Dawg
Joined
Jan 21, 2009
Location
Fort Worth, Texas
TDI
2009 Sportwagen (boughtback); 2014 Passat TDI SEL (boughtback)
AFAIK, identical heater core in dual and normal climate control, just different ducting.
 

jjblbi

Veteran Member
Joined
Sep 27, 2000
Location
lbi, nj
TDI
2014 Passat SEL TDI
I've done a number of different cars. A Volvo 240 was one of the worst - after removing the dash I still couldn't get to the core so I cut the top off of the housing, replaced the core and epoxied it back together.
Ahh the Volvo 240 heater core. This was my oldest son's first car, we got it cheap knowing it needed a heater core. The joke on the Volvo forums is the heater core is the first component placed on the assembly line and they build the car around it!
 

gforce1108

Top Post Dawg
Joined
Aug 2, 2006
Location
Newburgh, NY
TDI
04 Jetta GLS BEW, 14 Audi A7 V6 TDI, 13 Porsche Cayenne V6 TDI
My antifreeze was replaced multiple times each time using g12. Once for a turbo replacement the dealer took out the radiator, once for an accident, once when I installed my frost heater. I would assume any vehicle using this core and antifreeze combination would be suspect
Hmmm - I was hoping... :) Frostheater install shortly. This is an easy enough repair that I won't worry about it.
AFAIK, identical heater core in dual and normal climate control, just different ducting.
Good to know - I assume it'd just not have heat anywhere.
Ahh the Volvo 240 heater core. This was my oldest son's first car, we got it cheap knowing it needed a heater core. The joke on the Volvo forums is the heater core is the first component placed on the assembly line and they build the car around it!
That's pretty much what I said to the owner! 380k miles. Straight water, no thermostat and no radiator cap sealing (clues to what was waiting for me). Sentimental value to the car for her so it was worth it. I took it as a challenge.
 

snow patrol

Member
Joined
Oct 25, 2013
Location
Nevada
TDI
2014 SEL
Did you go with the original G12 coolant, G11+, or something else? I'm worried about a continuing reaction with the G12 causing my new core to clog again.
 

VeeDubTDI

Wanderluster, Traveler, TDIClub Enthusiast
Joined
Jul 2, 2000
Location
Springfield, VA
TDI
‘18 Tesla Model 3D+, ‘14 Cadillac ELR, ‘13 Fiat 500e
Did you go with the original G12 coolant, G11+, or something else? I'm worried about a continuing reaction with the G12 causing my new core to clog again.
I think the reaction has more to do with the presence of flux than with the type of coolant (G11, G12, G13). I could be wrong about that, as I'm not a chemist.
 

LeeM

Veteran Member
Joined
Jan 26, 2003
Location
Hagerstown,MD
TDI
2015 Passat SE, 2002 Jetta Reflex Silver
The TSB has the tech drain the system, refill with 50/50 mix and bring to temp, then drain and replace the heater core. Would it be better to find a piece of pipe/tubing that can connect the tubes coming from the engine compartment together after the first emptying of the coolant system. That's got to be better than trying to push fluid through a plugged heater core.
 

inthewoods

Veteran Member
Joined
Mar 24, 2014
Location
Carson, WA
TDI
2014 Passat SE Manual
The TSB has the tech drain the system, refill with 50/50 mix and bring to temp, then drain and replace the heater core.
Actually before the core is to be replaced my Dealer did multiple drain/fill/temp until the PH levels came to spec.

My car took 6 flushes to return back to normal. :eek:
 

dogger37

Veteran Member
Joined
May 28, 2012
Location
PA
TDI
2012 passat
Car at dealer now for second core replacement. Service manager said a cleaner would b used and then multiple flushes done before the new core was installed. Said the issue is caused by flux from the radiator. I will get more info and report back
 

VeeDubTDI

Wanderluster, Traveler, TDIClub Enthusiast
Joined
Jul 2, 2000
Location
Springfield, VA
TDI
‘18 Tesla Model 3D+, ‘14 Cadillac ELR, ‘13 Fiat 500e
A strong cleaner should be able to remove the flux from the system. It may take several operating cycles (bringing the engine up to full temp, drain, refill, repeat) to get it all out.
 

snow patrol

Member
Joined
Oct 25, 2013
Location
Nevada
TDI
2014 SEL
I tackled this project today. Took about 4 hours start to finish. Thanks to 767Wrench for the how to pictures. Some things I encountered...
Draining the coolant was done by disconnecting the radiator quick disconnectors on the middle and bottom passenger side hoses of the radiator after dropping the belly pan. I was able to drain out about a gallon and a half. Lots of reddish gritty sediment settled at the bottom of the bucket. I did two fill and flushes with 50/50 distilled water and G13 coolant. After the second flush, the coolant appeared clear of any solids. I left the system drained and tackled removing the core.
I loosened the 6mm clamp bolt for the heater tubes passing through the firewall using a nut driver with about 3/4 of the handle sawed off. It's really hard to see the recessed hole that the bolt lives in, but it's directly in between the inlet and outlet tubes. There was just enough room to fit my hand in there and loosen the bolt.
All the panels under the drivers side dash came out exactly as 767Wrench described. My sawed-off 6mm nut driver came in handy here. Now time to disconnect the core lines. You will need a 3mm allen wrench for the clamp screws. You bend them open and they come off away from the tubing. Pulling the lines apart was a bit of a bear. I had to bend the lower tube of the core as I pulled hard away from the lower engine supply tube. I quickly discovered a lot of the resistance was from the tight fit of the O-ring inside the joint. You just have to be patient. I'd say about a cup of coolant drained out once everything was opened up. Have a container or an old towel ready.
The core was very tight pulling out of the heater duct. As you slide in the new core, you have to push the engine supply lines forward to make room for the lines of the new core to pass by. I used a 12 inch piece of 2 inch diameter wooden doweling to do this, which worked well. Push forward with the dowel as you GENTLY pull back on the core tubing to get the tubing connections aligned. Once the tubing was aligned, I used 767Wrench's technique of placing the edge of my dowel against the lip on the core tube, and lightly tapping the dowel with a mallet. This quickly popped the tubing ends together with lip of the core tube flush with the supply tube. The gasket kit comes with new clamps, and they go on just like they came off.
I then filled the radiator with coolant, and took it for a test drive. No leaks and lots of heat once again!
 

mill424

New member
Joined
Sep 11, 2013
Location
San Antonio
TDI
2013 Passat TDI SEL
I'm in the middle of this project now....I pulled the lower passenger side radiator hose and might have gotten a gallon of Coolant out but something tells me there is more in the engine....is there another drain that I can tap to clear the remaining fluid from the core so I don't have a mess on my hands inside the car?
 

767wrench

Veteran Member
Joined
Jul 25, 2012
Location
Ohio
TDI
1981 Rabbit Pickup
I'm in the middle of this project now....I pulled the lower passenger side radiator hose and might have gotten a gallon of Coolant out but something tells me there is more in the engine....is there another drain that I can tap to clear the remaining fluid from the core so I don't have a mess on my hands inside the car?
You can pull this hoses off the core lines. I just didn't due to difficulty. I'll have to look at my car again to see if any lines are easier to get to for draining the coolant in the lines surrounding the engine.
 

verylongdrive

Veteran Member
Joined
Feb 10, 2005
Location
HSV
TDI
Golf,2001
I've been looking around for a how-to on replacing the coolant (for good measure, and to perhaps prevent clogging of the heater core in the first place), or the drain and refill needed before and after the heater core replacement.

I saw the term vacuum fill in another post, and searching for that, I found some commercial tools, as well as a recommendation in TDI 101 (for A5s) to refill by filling the overflow tank and pulling slight vacuum on the upper tank hose.

Assuming this works on the NMS, could one also use this method to cleanly drain a sizable fraction of the coolant on the engine side (as opposed to radiator side) of the thermostat?
 

YukonLT

Veteran Member - TDIClub Enthusiast
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Nov 28, 2012
Location
N/A
TDI
2010 Golf TDI 6MT
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