PTC heater burning smell

[SuperV8]

I've got the exact same car and I'm pretty sure I don't have a ptc heater. The EA288 engine has two coolant circuits in the cylinder head specifically designed for faster cabin warm up. I know mine starts to chuck out warm air by the time I get a couple miles up the village bypass on my way to work. Maybe just the first few months of cars had them ??

I agree - my car starts blowing warm air within 2 - 3 miles in the morning so electric PTC heater is kind of pointless - maybe beneficial when -10 outside!
Just to confirm as can be seen by my previous post photo - I do Definitely have a PTC heater. I looked at the later model years and couldn't see a PTC part number listed so maybe it has been dropped.

Have a look in your AC settings and see if you have a aux heater option?

 

[BillyCool]

I agree - my car starts blowing warm air within 2 - 3 miles in the morning so electric PTC heater is kind of pointless - maybe beneficial when -10 outside!
Just to confirm as can be seen by my previous post photo - I do Definitely have a PTC heater. I looked at the later model years and couldn't see a PTC part number listed so maybe it has been dropped.

Have a look in your AC settings and see if you have a aux heater option?

I've got the same car as you and have the same wiring. Mine looks clean though and like you say, the burning/overheat could suggest a bad earth.

 

[BillyCool]

Might be unrelated but it's not nothing to do with that fact that the wire terminal is touching this screw? Mine doesn't do that.

 

[SuperV8]

Might be unrelated but it's not nothing to do with that fact that the wire terminal is touching this screw? Mine doesn't do that.


View attachment 19741

I will double check - i'm pretty sure I noticed this and re-adjusted the ring terminal - but if this is the issue then it is shocking design to not have the ring terminal restrained

 

[jonial]

I will double check - i'm pretty sure I noticed this and re-adjusted the ring terminal - but if this is the issue then it is shocking design to not have the ring terminal restrained

Another possibility is that the ring terminal crimp is not perfectly tight and a small amount of resistance is present and the heating effect of current through this small resistance is creating the heat. Can you solder rhe copper wire to the ring connector thus eliminating any possibility of this resitance if not try sqeezing the crimp connector with a pair of pliers.

 

[SuperV8]

Another possibility is that the ring terminal crimp is not perfectly tight and a small amount of resistance is present and the heating effect of current through this small resistance is creating the heat. Can you solder rhe copper wire to the ring connector thus eliminating any possibility of this resitance if not try sqeezing the crimp connector with a pair of pliers.

Double checking and yes the ring terminal isn't touching the bolt. Was an older photo I shared.
You can see the insulation by the crimp has bubbled so must have got very hot! This photo is just peaking through the glove box.
The crimp does look well 'crimped' when I have time next I will try checking the resistance from the terminal to earth and to the cable to see if there is a bad connection/high resistance?

 

[Smilerr]

Hi ,mate thanks a lot. I switched off I went to vw specialist today anyway for my service he told me is a recall for this just need call seat they change the part for free but I'm not to sure I can't find any information for this

 

[SuperV8]

Hi ,mate thanks a lot. I switched off I went to vw specialist today anyway for my service he told me is a recall for this just need call seat they change the part for free but I'm not to sure I can't find any information for this

Thanks, very interesting. If you find out more information please let us know.

 

[RUM4MO]

Normally with wiring, if there is signs of the insulation getting hotter than expected, it means that the crimped terminal is not tight enough and so volts are being dropped over it which equates to heat, the only other option is heater heat is being transferred out to that area, it would cost money to get SEAT to attend to this, in as much as if the car is outside warranty, that recall action info has probably now been lost from service system's information system and would need to be recalled via the dealer's service tech submitting a technical support query to SEAT Mothership.
I'm guessing that this is not being considered by VW Group to be a safety related issue, and so nothing will get done unless the customer complains or reports this issue, which will get resolved FOC within warranty - the parts should always be provided FOC when outside warranty period, but only if the customer first hands the car in to get examined to prove that the issue is what the recall covered.

 

[SuperV8]

Hi ,mate thanks a lot. I switched off I went to vw specialist today anyway for my service he told me is a recall for this just need call seat they change the part for free but I'm not to sure I can't find any information for this

what year is your car mate?

 

[SuperV8]

Normally with wiring, if there is signs of the insulation getting hotter than expected, it means that the crimped terminal is not tight enough and so volts are being dropped over it which equates to heat, the only other option is heater heat is being transferred out to that area, it would cost money to get SEAT to attend to this, in as much as if the car is outside warranty, that recall action info has probably now been lost from service system's information system and would need to be recalled via the dealer's service tech submitting a technical support query to SEAT Mothership.
I'm guessing that this is not being considered by VW Group to be a safety related issue, and so nothing will get done unless the customer complains or reports this issue, which will get resolved FOC within warranty - the parts should always be provided FOC when outside warranty period, but only if the customer first hands the car in to get examined to prove that the issue is what the recall covered.

Looking in the Seat Manual I can confirm the large brown wire is an earth as suspected.
I have looked at a couple of resources and can't find any recall for my car Reg. There is a recall on Audi Q5/A4 I can see on the PTC aux heater.
I have also found there is 3x supersessions of OE numbers
5Q0963235 Denso
5Q0963235B Denso
5Q0963235C Valeo
And the comment: Dropped: Jan 1, 2016 (EKZ: L)

Maybe worth a phone call to Seat.

 

[BillyCool]

Looking in the Seat Manual I can confirm the large brown wire is an earth as suspected.
I have looked at a couple of resources and can't find any recall for my car Reg. There is a recall on Audi Q5/A4 I can see on the PTC aux heater.
I have also found there is 3x supersessions of OE numbers
5Q0963235 Denso
5Q0963235B Denso
5Q0963235C Valeo
And the comment: Dropped: Jan 1, 2016 (EKZ: L)

Maybe worth a phone call to Seat.

I'd do what you suggested and check the resistance running through it. I've also looked and can't see any recall info for that year/model.

 

[RUM4MO]

I'd think that you would need a quality milliohm meter to check for resistance at that point, an IR thermometer or a finger on that area would work better to sense where the issue is.

Edit:- if you have easy access to that area, maybe try to connect a second heavy earth lead to that point and check to see if doing that reduces the temperature at that point.

Another Edit:- maybe better to check the voltage between that stud and a good local earth point, before and after applying a 2nd earth lead.

 

[SuperV8]

I'd think that you would need a quality milliohm meter to check for resistance at that point, an IR thermometer or a finger on that area would work better to sense where the issue is.

Edit:- if you have easy access to that area, maybe try to connect a second heavy earth lead to that point and check to see if doing that reduces the temperature at that point.

Another Edit:- maybe better to check the voltage between that stud and a good local earth point, before and after applying a 2nd earth lead.

Thank you for this, I tried measuring the resistance at various points on the PTC heater and struggled with my standard multi meter as the resistances were less than 1 ohm.
I was surprised to see the heater I have below:
Mostly black plastic - feels very flimsy - and also has the SAME OE number as other alloy PTC's I have seen.

So VAG have updated to this with the SAME OE number!

And the latest C number is from Valeo looks like this:

The plastic arround the earth terminal has started to degrade - so has obviously got hot!
It is brown plastic on mine - and black on these later versions - maybe a better/more suitable grade?

Tried measuring the resistance between the large brown cable and the ring terminal and got arround 0.3 ohms.
Does this seem reasonable? Or is my measuring flawed/not accurate enough? I think this is flawed method for measuring resistance in high current cables.

Also tried measuring resistance between earth cable and earth terminal on heater - again I think beyond the accuracy of my multi meter,

I should probably do a voltage drop test over this cable/terminal - trouble is I can't control when the PTC heater turns on.

This is the resistance of one of the 3 PTC circuits in the heater - each was arround 0.8 ohms.

any ideas?

Thinking of just getting a later PTC heater of ebay and see how that works.

 

[RUM4MO]

We used to resort to feeding a high current down suspect high current leads where there was a need to check for high integrity and then voltage drop across the suspect section, it was either that or use a high grade milliohm meter.
Another thing, you will need to confirm where the unwanted extra resistance is, is it at the lead’s crimping point, or at the stud but on the PTC heater end side and conducting the heat through that stud.

EDit:- I’d think that that must be your best plan, as well as investigating buying a new lead, a genuine later lead from a VW Group dealership.

 

[SuperV8]

We used to resort to feeding a high current down suspect high current leads where there was a need to check for high integrity and then voltage drop across the suspect section, it was either that or use a high grade milliohm meter.
Another thing, you will need to confirm where the unwanted extra resistance is, is it at the lead’s crimping point, or at the stud but on the PTC heater end side and conducting the heat through that stud.

EDit:- I’d think that that must be your best plan, as well as investigating buying a new lead, a genuine later lead from a VW Group dealership.

Thanks for the help, I looked at a new earth lead but I think its part of the engine harness which is very expensive.

As I can't test it under load from the car - computer controlled activation I have no control over, and I haven't got a milliohm meter - I think i'll try and rig up a spare car battery, earthed to the body, and have the positive to a spade terminal to each of the 3 spades on the positive PTC connector. Then with my DVM measure the voltage drop across each part of the PTC heater and earth terminal. To try to narrow down the heating issue to the ring terminal or the PTC its self.

Does this sound like a good/sensible plan?

 

[RUM4MO]

I was wondering if the official fix was to replace that lead, would the repair kit just include a heavy earth lead and the original was disconnected and cut back and capped, as I'd doubt if VW Group would be interested in replacing an expensive cable harness.
Hopefully buying a later and so maybe improved heater, would fix this problem.

The problem with messing about with the PTC heater under your control is, in normal use it might only get fully switched on for short periods then pulsed to control the heat output safely.

Maybe a tricky issue to fix first time, it would help knowing what the usual problem that prompted an official fix from SEAT was - if only as a starting point.

If I was in your position, the first thing that I would do would may to make up a heavy gauge earth lead, and using a second nut, connect that to the PTC heater where the earth lead is already, then terminate the other end at a suitable body earth bonding point, ie one that provides the same size of earth bonding stud, hopefully again using a second nut. Then using the car as normal and see if the smell and temperature of that original lead has dropped. If it has, then the problem must be the original earth cable or its crimped connector. If the earth leads are both now getting hot then the issue must be the heater<>stud junction, or someone has messed up properly and the heat built up in the PTC heater is leaking out to the earth cable and its insulating material needs to be changed form PVC to something like PTFE or some other plastic capable of withstanding higher temperatures, and maybe even the materials used on the PTC heater casing is also overheating and melting/flowing slightly again giving rise to a poor electrical connection due to the stud now not being properly supported by the case of the heater - all a bit messy to work out really - even the PTC supply control could be causing this overheating.

 

[RUM4MO]

One maybe last thought, is that stud loose or slack in the body of that PTC heater, ie has the local overheating allowed the plastic to flow? If so you would need to check the inside area at that point and try to retighten the end of the PTC heater to that stud, if that is not possible then a new heater is required now anyway. Though unless some initial looseness had caused the plastic to flow, you are still left guessing what the root cause of this is.

As I said earlier, you need to talk to SEAT UK or a dealership to get them to try to locate the required workshop action and its content.

If that crimped tag has not been crimped correctly when that cable harness was built, the over heating will have tarnished the strands of the multi strand flexible cabling and just trying to close that crimp a bit more will not be a useful action, a short section of wire will need to be cut off back to clean shiny wires and stripped and a new crimp fitted - if it is now long enough.

 

[SuperV8]

Update:
I managed to get the PTC heater out yesterday - had to remove quite a few screws securing the dash, also from behind the HVAC and screen to give enough wriggle room of the dash to 'just' allow me to slide out the aux heater.
I could clearly 'feel' the earth terminal was loose to the earth return strap which will obviously cause a high resistance and melted plastic!

Interesting design, the thin 'brass' colour strips are the positives, the thicker aluminium colour strip is the ground/return

The latest PTC has a revised design 5Q0963235C:

 

[SuperV8]

While I was fitting my new heater matrix I also fitted a new PTC heater. 5Q0963235C this new design feels so much more sturdy than the previous piece of flexible junk.
Obviously the PTC heater won't be turning on until next winter but nice to know it's sorted.