PTC (Auxiliary) Heater [WIP GUIDE]

[BilTechnik]

This is going to be a guide of how to fit the PTC heater option using the OEM control system and OEM parts. Its going to be a work in progess/follow along style, but I'll edit this post when its complete with all the information you need. With currnent eBay and dealer prices, the whole job costs less than £100 and could be easily completed in a weekend.

 

First thanks to @Crocket@piggoy@Breezy_Pete@jacissmiling for all the effort on the original thread

[BilTechnik]

So this started a few weeks ago when my Fabia started leaking cooling. After a lot of searching around, I found it coming from the bulkhead where the heater matrix connects. There are two alloy pipes that go into the matrix, with a braket attached at the top. Except in my case, the bracket was no longer attaced (what 200k miles does to aluminium). Initially I thought that heater matrix would have cracked too (not just damaged O-rings) , so I was preparing to swap that.
I started looking for a new matrix, and while doing so came accross a PTC heater for £30. An eBay offer later and I had an original Skoda PTC for £15, including clips and bottom housing! See eBay pictures below.

 

 

I did confirm it was an option, and the part codes were right for my car before purchasing, but that was as far as  I got. As I understand this is the earlier version, that has been superceeded twice to get to the version that fits in the Polo 6R. The following link is an excellent page that shows the newer style, and has some good wiring diagrams, albiet wrong for a Fabia. https://polo.blue/2018/09/02/ptc-retrofit/

 

Another eBay best offer later, this time of £20, resulting in a 120 amp alternator (thanks @varooom and @Breezy_Pete for the info). Hopefully this is a direct fit. My car has a 90 amp alternator as standard, I will try with that first and log the load factor with VCDS to see if it's viable to not upgrade. You can also get a 110 amp version for a similar price.

 

Now for the bits from the dealer, this is the expensive bit. I'm going for 100% OEM, so you could omit these and go for generic parts if you want.

6Q0937617B  Fuse holder, will add price later but around £10

 

N01713120 40 amp fuses to go in said holder, you need 3 - Around £1.50 each

1J0972753  - Plug to connect to the PTC heater - Around £10

 

4B0937527A - Relay plate. You need two. These are around £14 from a dealer which I refuse to pay, so I'll be getting used. It can be any part number, justs needs to fit in the relay frame and support large pin (will confirm dimension) relays.

As for the pins, I'll be ordering them from TE connectivity so I can crimp them to my own wire, and avoid having to splice to repair wire. The OEM relays are number 644 and 645. I will instead be using 70 amp rated Panasonic items as they are far cheaper, and new.

Will update once everything arrives, and once I have details on the pins finalised.

 

[BilTechnik]

This is also a dash out job, You could maybe do it with the dash in, but it would be very hard to route the wires almost impossible/impossible to connect to the bulkhead where you need to (same place as cruise control but you need to connect a large power wire too). It takes a couple of hours and is far less scary than people assume, definely easier than struggling to do it with the dash in, in my opinion.

[BilTechnik]

@varooomsorry to be pain but could you check something on ETKA for me? The repair wires for the "medium" pins of  4B0937527/4B0937527A (3 and 4 of the picture in the last post). If you could get a picture of them that would be great, and if not just the part number would be a start

[BilTechnik]

To answer my own question, I think they're 000 979 236, with the pin N 103 197 01.

I can find information on the former, but basically nothing on the latter.What's odd is that it seems like you can only get 2.5mm2, even though from the factory those positions normally have 0.5mm2 wire

[varooom]

I shall try to look at things in a while, unless someone else has a look, out on the road at the moment.

[Breezy_Pete]

1/4" spade receptacles sounds about right

10 PLAT STECKHÜLSE 6,3 mm 1,5-2,5 ² N 103 197 01 similaire à 000 979 236 E relais PIN EUR 7,50 - PicClick FR

[Breezy_Pete]

I've probably got one of each relay in a box in the shed, but from memory, at least one of them has the whopping 3/8"/ 9.5 mm wide main contact terminals, then 6.3mm for the coil contacts. 

[Breezy_Pete]

You'd be welcome to any of these bits should they be useful.

The left two relays are equivalent I think, pins are oriented opposite just to show what's written on each.

Connector looks to be the only genuine bit, but it's the male pin part from the heater, not the loom.

 

Edited 24 August, 2022 by Breezy_Pete

[BilTechnik]

Cheers @varooom, mainly interested if they do a smaller cable size. Well I know they do, but I wonder if its actually purcasheable.

 

Yeah I've seen those ones, they are the correct type but again they only go down to 1.5mm2 wire, wheras the ones on the car currently are definetly 0.5mm2.

 

The 9.5 mm terminals are "easy" to get really, they're Delphi/Aptiv Ducon connectors.

Its just these 6.3mm ones, they seem totally unique. Normally all the VAG stuff is TE group or Delphi, but these are neither of those. I've found two other people who've tried to identify them in the past but failed. I think I could probably make an Aptiv M/P or 56 work, but they're a bit harder to get, and obviously not the right ones.

[BilTechnik]

7 minutes ago, Breezy_Pete said:

You'd be welcome to any of these bits should they be useful.

Thanks very much! I actually ordered the relays earlier today otherwise those would have been handy

[Breezy_Pete]

Are both of the 'real' relays the same contact pattern as each other (or simply  the same part)? I had it in my head that one was smaller, with 4-off 1/4" spade contacts (like the RHS relay in my photo), but if so how do they both fit that same relay socket?  

[BilTechnik]

From what I can find, 644 and 645 are the "real" relays. And they are different, 644 is green and has 2-off 9.3 mm and 2 of 6.3 mm (so fits in that socket). 645 is just a standard relay with 4-off 6.3mm terminals as you mention, and the factory install uses a different socket for each one. The 4-off 6.3mm sockets use Power time/ JPT pins so very easy to get pins for, but they obviously can't take the large pin relays.

[Breezy_Pete]

Just now, BilTechnik said:

the factory install uses a different socket for each one

Ah, OK. 🙂

 

[varooom]

4 hours ago, BilTechnik said:

@varooomsorry to be pain but could you check something on ETKA for me? The repair wires for the "medium" pins of  4B0937527/4B0937527A (3 and 4 of the picture in the last post). If you could get a picture of them that would be great, and if not just the part number would be a start

I was only acutally able to pull this part number up in ETKA, the A part seems to have been removed.

It's kinda limited in the "possible single wire"

 

4 hours ago, BilTechnik said:

To answer my own question, I think they're 000 979 236, with the pin N 103 197 01.

I can find information on the former, but basically nothing on the latter.What's odd is that it seems like you can only get 2.5mm2, even though from the factory those positions normally have 0.5mm2 wire

4B0 937 527 Repair kit - assembly.pdf

Attached is the Repair kit/assembly that shows many more choices, let me know if this even helps (I might be a little late to the party as busy night)

I can pull up images for each if needed should that assist.

[BilTechnik]

Cheers, yeah the dealer said about the A part number not existing. Its just a colour difference as far as I can tell so no worires.

That's frustrating, but very helpful though thank you!

 

000 979 144 / 000 979 144 E (different temperature rating) seems like as close as I'm going to get. 1.0mm2. Do you know if VAG sell just the pins? N 103 197 01 is meant to be just a pin part number

[BilTechnik]

If it turns out I can't get the pins, I might take a bet on getting the pins from TE. Delphi made the harnesses in the Fabia, but they used also exclusively TE/Tyco pins and connector housings. One of the few bits on the car where Delphi used there own pins are these relay holders (large pins are 100% Delphi Ducon, the medium pins discussed above are possibly delphi, the small pins and TE Timer).
As everything else is designed by TE, I wouldn't be surprised if the relay holder was too, meaning they would have most likely designed to fit both TE and Delphi terminals (evidenced by the use of TE Timer pins for the small connections).

Looking at the MCP and MCON series from TE, they look very similar to Delphi Ducon and I'm fairly sure they would fit. The mystery pins I suspect might actually take a standard style spade terminal, or worst case a semi locking terminal like the Aptiv M/P shown above.

It's an option at least if I can't source the actual pins from the dealer.
Apologies, I know talking about pins isn't the most exciting topic for everyone, but hopefully it's a nice bit of information gathering

[Breezy_Pete]

I understand your purist wish to have everything 'just so' and OEM, but if you're already going to be fitting secondhand relay holders, why not just extract the pins/wires that come with them, bin the large ones and replace, re-use the 6.3mm ones by either connecting onto the existing wire, or cutting that back close to the crimp and soldering onto your loom.

They're only going to be carrying, what, 50mA of coil current or something, sub-critical.

 

Nice to get a full list of parts required for anyone interested though. 

Edited 25 August, 2022 by Breezy_Pete

[nige8021]

https://skoda.7zap.com/en/cz/elekt+verbind-elem/el/2004-698/9/ lists all the contacts/connectors

[BilTechnik]

Yeah that's always an option, I'm just really curious..

 

Success!! N103 196 01 is Lear Corporation SIKO 1 6,3 series, with the part number of 3202557S2. Catalog here, the legacy part number is: 26817.213.178 https://www.mouser.com/catalog/specsheets/Lear Catalog.pdf

I'm totally lost why they used such an odd terminal, but that is definetly it. Available here: https://www.autokabel.cz/kontakt-siko1

[BilTechnik]

Courtesy of Szymon from Polo.blue, very handy. Actually has the SIKO 1 terminals listed, but they're not really possible to buy in sane quanities: https://www.a4-freunde.com/showwiki.php?title=Pins+und+alles+was+dazu+gehoert&s=058c034889a10e0ca5c7307ce9a4ef45&page=2

[Breezy_Pete]

Wow, love it when people put such great resources out there. 

[BilTechnik]

Yeah its the best I've seen for a while. Other projects of mine I've used TE for help identifying pins and connectors. They're barred from releasing some information because of NDA but they're very, very helpful up to that point, even if you say you're just doing one off work with no commerical interest.

Any PTC has arrived and looks really good, was nicely packed and all elements show continuity which is good. I'm getting some Xpanda expanding foam tape to replace the disengrated stuff in various areas. Seems promising and is fire rated which makes me feel more comfortable using it around the PTC. Will report back if its any good
 

[BilTechnik]

Some pictures of the various parts so far. Genuine O-rings, fuses and fuse holder, along with the connector for the PTC. The second hand alternator came and I stripped it, its from a 2007 Polo, as aside from being dirty is in pretty good condtion, lots of material left on the brushes. There are some pictures of the PTC and associated lower covering too. You can see the brown residue where there was once foam tape, and its location is why I wanted something fire retardent.

[BilTechnik]

Fitted the heater back into the car today, which took far longer than it shoud have. I'm using some Xpanda foam tape which is good, but is more dense than the orignal stuff. I think this pushed the bottom of the heater box slightly out of shape. This combined with the firewall grommet that goes around the heater matrix made it almost impossible to fit. In the end, I had to get one side partially clipped in, and brace myself against a wall to force the otherside far enough for it to clip in too. I'll post some pictures tomorrow. Its all clipped in nicely now and isn't under stress, so I don't think anything is wrong. I may take it off again tomorrow to see if the foam has settled and nothing has been trapped, I don't want to be taking everything apart again if something isn't right.